faxtor beamline proposal sin referencias cruzadas · 4.4.1. in‐situ tomography of the fluid...
TRANSCRIPT
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AFastXrayTomographyandRadioscopyforAlbaWorkingteam:
FedericoSketEusebioSolrzanoJuanGomezBarreiroJoseAntonioYagFabraBartBijnensVicenteGomezRuizdeArgandonaFranciscoGarcaMoreno
Albaworkingteam:
EvapereiroSalvadorFerrerJosepNicolasXabierMikelTurrillasJordiJuanhuixJosepCampmanyGuillotMiguelA.G.Aranda
Peregrine falcon is one of the FASTEST animals in the planet with capacity of diving at 300km/h We have decided to use this animal as a representative icon for the future FAST TOMOGRAPHY beamline
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TABLE OF CONTENTS 1. ABSTRACT........................................................................................................................11
2. INTRODUCTION...............................................................................................................12
2.1. ImportanceofXrayimagingandtomography.......................................................12
2.2. VirtuesofXraytomography...................................................................................13
2.3. DevelopmentofSXCTinthelastdecades...............................................................14
2.3.1. 4Dtomography................................................................................................16
2.3.2. Insitutomography..........................................................................................17
2.4. Scopeofthisproposal.............................................................................................18
3. THESPANISH(ANDEUROPEAN)USERCOMMUNITY......................................................19
3.1. CurrentpanoramaofSXCTinEurope......................................................................19
3.2. PotentialusersinSpain...........................................................................................20
4. RELEVANTSCIENTIFICCASES...........................................................................................23
4.1. MultidisciplinaryFasttomographyandradiography:insitustudies......................23
4.1.1. Bubblenucleationandgrowthcharacterizedbyultrafasttomography.........23
4.1.2. InsitusolidificationofAlalloys.......................................................................26
4.1.3. Understandingexplosivevolcanoes:riskevaluationthroughmorphometricanalysisofbubblesandcrystalsinlava...........................................................................30
4.1.4. Foodscience:tastingthetexture....................................................................33
4.1.5. Ultrafast2DRadioscopyoncellwallrupturestostudymetalfoamstabilitymechanisms.....................................................................................................................35
4.1.6. Insitutomographyofcreepprocessofbrass.................................................38
4.1.7. Insitutomographyofdamagedevelopmentofcarbonfiberreinforcedcomposites......................................................................................................................40
4.2. Materialscience......................................................................................................42
4.2.1. ResinmicroflowbyXraycomputedtomography...........................................42
4.2.2. 3DmultiphasenetworksprovidinghightemperaturestrengthtoAlSipistonalloys 44
4.2.3. Submicrometerholotomographyofmultiphasemetals................................47
4.3. Lifesciencesandbiomedicine.................................................................................50
4.3.1. HighresolutionStructuralImagingofstatictissue:........................................51
4.3.2. HighthroughputVirtualPathology.................................................................52
4.3.3. Highspeeddynamicimagingoffunctionalorgans.........................................53
4.4. Historicalbuilding....................................................................................................54
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4.4.1. Insitutomographyofthefluidmovementinsiderocks:applicationtohistoricalbuildingconservation......................................................................................54
4.5. Biology.....................................................................................................................57
4.5.1. Investigatingthecontinuousdentalreplacementofmammalsthroughanewrodentmodel...................................................................................................................57
4.6. Paleontology(foraminiferatomcat).......................................................................60
4.6.1. Morphologicalcharacterizationoffossils.......................................................60
5. BEAMLINECONCEPT,LAYOUTANDREQUIREMENTS.....................................................62
5.1. Technicalrequirements...........................................................................................62
5.2. Source......................................................................................................................63
5.2.1. Sourceproperties............................................................................................63
5.3. MultilayerandSi(111)monochromators................................................................65
5.4. Beamlinelayout.......................................................................................................68
5.5. Experimentalendstationanddetectionsystems...................................................69
5.5.1. Samplepositioningsystem:.............................................................................69
5.5.2. Imagingsystems..............................................................................................72
5.6. Sampleenvironment...............................................................................................75
5.6.1. Tensile,compression,fatiguetestrigs............................................................75
5.6.2. Hightemperaturefurnace...............................................................................77
5.6.3. Cryogeniccell...................................................................................................79
5.6.4. Highpressurecell............................................................................................80
5.7. Computationanddatastorage...............................................................................80
5.8. Estimatedbudget....................................................................................................82
5.9. Futuredevelopment................................................................................................83
6. REFERENCES....................................................................................................................84
ANNEX1.LettersofsupportfromSpanishcompaniesandrelevantinstitutions..................89
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TABLE OF FIGURES
Figure1.Tomographicmethodsspanningover9ordersofmagnitude[11]........................................13
Figure2.Scientificproductionconsideringsynchrotrontomographyoverthelast20years(a)Numberof indexed publications (b) Cites per year, total number of cites and hindex for synchrotrontomography. (c)Scientificproduction considering synchrotron tomographyanddiffractionover thelast20years.Thenumberofpapers isnormalized to themaximumnumberofpaperperyear. (d)Relativenumberofpaperfordifferentspecifictomographictechniques(normalizedtothemaximumnumberofpaperperyear).(e)Publicationbysubjectforsynchrotronmicrotomography.Source:WebofScienceandScopus............................................................................................................................15
Figure 3.Map of Europe including the list of European Synchrotronswith available tomographictechniques..............................................................................................................................................19
Figure4.GeographicdistributionofthesupportingclusterintheIberianterritory.............................22
Figure5.Detailof the stirringheadover the kaptonmould containing the isocyanate and polyolblendsbeforethemixingprocess..........................................................................................................24
Figure 6. Volume rendering at different instants for the two examinedmaterials (TOP: pure PU;BOTTOM:PUwith3%wt.nanosilica)at(a)9.8s,(b)21.7s,(c)26.3sand(d)32.6s).............................25
Figure7.Left: Insitucelldensityevolutioncomparedmodels.Right: Insitucelldiametercomparedwiththetheoreticalmodels...................................................................................................................26
Figure8.ReconstructedtomographicslicesobtainedduringinsitusolidificationofAlMg4.7Si8atthetemperaturesatwhichconsecutivesolidificationofthedifferentphasesisobserved,[38]................28
Figure9.a) tod): rendered3D imagesof theAldendriticsolidificationatdifferent temperaturesduringcoolingofanAlMg4.8Si7alloyobtainedinsitubySXCT.e)toh):distributionofthemeanandGauss curvatures of the surface of the Al dendritic structure at the different stages of thesolidificationprocess.[38]......................................................................................................................29
Figure10:Bubblesize,wallthicknessandinterconnectionfrombasalticfoams[53]...........................30
Figure11:Differentpyroclasticmicrotexturesfromsilicicmelts.Bubblesappearsegmented[56].....31
Figure12.(a)3Ddesignand(b)topphotographofthelasersystemmountedonTOMCATbeamlineatSLS.Trangeis4001700C[58,59].........................................................................................................32
Figure 13. ac 3D rendering of acid melt at different temperatures (bubbles); d) bubble sizedistributionsatdifferenttemperatures;e)bubbleanisotropyandfractionversustemperature[59].33
Figure14.Evolutionbubblesinbreadduringproofing:(a)2Dimagesofhorizontalsections(diameter9mm)extractedfromreconstructedvolumes(628x628x256voxels)(b)and(c)Voidvolumefractionandaveragecellwallthicknessforthreedifferentdoughs[68]............................................................34
Figure15.(upperleft)Synchrotronradiationtomography:phasecontrastslicesofthefruitcortexofapple (left) and pear (right); cell walls are indicated by arrows. (lower left)Modeled (a) againstmeasured(b)3Dgeometryofapplecortexcells.(Right)Theoxygenconcentrationprofileinsidecellsusingfiniteelementsimulations.Drivenforcewaspartialpressureacrosstheboundariesofthetissue.Thepartialpressureandconcentrationinsidethetissuewasrelatedbytheuniversalidealgaslaw[65].................................................................................................................................................................35
Figure16.Evolutionof time resolution for insitu synchrotronXray radioscopyapplied tovisualizemetalfoaming........................................................................................................................................36
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Figure17.SeriesofradiographsofanAlSi10+0.5wt.%TiH2foamat640Cextractedfromaninsitufast synchrotron Xray radioscopic analysis. The coalescence of two bubblesmeasuredwith 9.5sframe interval (105kfps) can be observed.Dashed lines indicate the contours of the bubbles andarrowsindicatethecorrespondingrupturedcellwall...........................................................................37
Figure18.Tomographicvolumes revealing thecavitiesatdifferent timesduring thecreep test. (a)initialcondition,(b)middleofthetest,(c)closetofracture.................................................................38
Figure19.Shapeevolutionofthethree largestcavitiesexhibitingcoalescence. Thedifferentstagescorrespondtothelargestporebeforecoalescence...............................................................................39
Figure20.Evolutionofthespatialorientationofcavities......................................................................40
Figure 21. Damage propagation in 45 plies. Different crack colours indicate their connectivity(adaptedfrom[17])................................................................................................................................42
Figure22.Experimentalsetuptostudy insituthe infiltration processattheP05beamlineofDESYSynchrotron............................................................................................................................................43
Figure23.(a)Crosssectionofthescannedfibertowspecimeninthevacuumbag.Wetglassfibersaresurroundedbythelightergreycolor.(a)3Dreconstructionoftheinfiltratedtow...............................44
Figure24.3DstructuresofaluminidesandSiafter4hofsolutiontreatment:a)SiinAlSi12,b)Siandaluminides in AlSi12Ni, c) aluminides in AlSi10Cu5Ni1, d) aluminides in AlSi12Cu5Ni2, e) Si inAlSi10Cu5Ni1andf)SiinAlSi10Cu5Ni2..................................................................................................46
Figure25.Proofstress0.2at300Cfortheinvestigatedalloysasafunctionofthesolutiontreatmenttime........................................................................................................................................................47
Figure26.Top:scanningelectronmicrographsoftheinvestigatedmaterialsBottom:portionsofslicesofholotomographyreconstructionsofthe investigatedmaterials.From lefttoright:AlMg7Si4alloy,Ti1023alloyandTi64/TiB/5w.................................................................................................................49
Figure 27. Rendered volumes of the investigatedmaterials: a) interconnected SiMg2Si structure(green)inAlMg7Si4;b)largerparticlesremainingfrompreforging(blue)andindividualsecondarygrains (semitransparentgreen) inTi1023; c)TiBneedles (green)and irregularly shaped grains inTi64/TiB/5w(othercolours)...................................................................................................................50
Figure28.Phasecontrast imagingofwhole (rodent)hearts.Beside the anatomicaldetail atorganlevel,thedetailedfibrestructureinwhichmyocytesareorganisedcaneasilybeassessed.Additionally,vesselscanbeobservedandextractedusingcomputationaltools[89]................................................51
Figure29.Imageofapretermrabbitpupthorax,focusingontheair/lungtissueinterface[90].........51
Figure 30. Spatial resolution of histology, Xray phase tomography, and MRI microscopydemonstratingthatresolutiondecreasesfromhistologyviaPCmCTtomMRI[91].............................52
Figure31.AfalsepositiveMRIpostmortem,suggestinglungchangeswhilehistologywasnormal....52
Figure 32. Breathing activity and the increase in endexpiratory lung gas volumes from birth in aspontaneouslybreathingnewbornrabbitpup.PhasecontrastXrayimageswereacquiredatthetimesindicatedbythearrowsdemonstratetheincreaseinlungaeration[94]..............................................53
Figure33.a)Uniformdistributionofthemineralsexcept in ironoxides layers(atthebottom).b)(1)voidspaces;(2)finegrainedcarbonates;(3)largegrainedcarbonatesand(4)claysandironminerals.................................................................................................................................................................54
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Figure34.a)CTimagesshowingthevariationinwaterpenetration.b)3Dimagesoftheopenporosity.................................................................................................................................................................55
Figure35.CTimagesatdifferenttimesduringtheabsorptiontest.ThepositionsofnineROIsusedtoquantifythewaterpenetrationrateareindicated................................................................................56
Figure36.EvolutionofthemeanCTnumberoftheinternalROIs......................................................57
Figure37.a)Foresideofacaptivesilverymolerat,b)3Dreconstructionandc)Virtualcrosssectionoftheupperdentitionofanadultsilverymolerat....................................................................................58
Figure 38. a) 3D reconstruction in lateral view of a lower tooth row and b) model of dentalreplacementofthesilverymolerat.c)3Dreconstructioninlateralviewofalowertoothrowandd)modelofdentalreplacementofthepygmyrockwallaby(greenarrows:molarprogression;redarrow:toothloss)...............................................................................................................................................59
Figure39.RightchelalfingersofaPseudogarypussynchrotron[103]fossiltrappedinamber............61
Figure40.HorizontalphasespacedistributionoftheWS400source....................................................64
Figure41.Horizontalspatialfluxdistributionofthesourcefor4photonenergies,forlowenergiesaparasiticsidelobeappears.....................................................................................................................64
Figure42.Photonsourcedistributionfor(verticalandhorizontal)forthreephotonenergies............65
Figure43.Fluxemittedwithinahorizontalacceptanceof1mrad,fortheproposedsourcecomparedtoabendingmagnet..............................................................................................................................65
Figure44.Bragganglefora4nmmultilayermonochromator,andforaSi(111)crystalpair...............66
Figure45.Verticalsizeoftheilluminatedarea(DoubleMultilayerMonochromator=DMLM)...........67
Figure46.Sampleilluminationareafortwodifferentvaluesoftheenergy.Thestripesarecausedbytheslopeerrorofthemultilayer(ML)mirrors.......................................................................................67
Figure47.Schematicopticallayoutoftheimagingbeamline................................................................68
Figure48.LayoutoftheImagingbeamlineattheALBAExperimentalHall...........................................69
Figure49.ZoomedphotographyofasystemsimilartotheoneintendedtoinstallatAlba(CourtesyofPIMicosIberia)........................................................................................................................................71
Figure 50. Schematic description of the twomicroscopes considered to bemounted at FaXToRbeamline.................................................................................................................................................72
Figure51.Left:3DrenderingofthewhitebeammicroscopemountingaPCO.Dimaxcameraontop.Right:photographyofaPCO.DimaxHScamera....................................................................................73
Figure52. Left:3D renderingof themonochromaticbeammicroscopemounting aPCO.Edge4.2cameraontop.Right:photographyofaPCO.Edge4.2.........................................................................75
Figure 53. 3D CAD rendering of a tensile/compressive test rig compatiblewithmicrotomographyexperiments............................................................................................................................................77
Figure 54. Cross section of the radiation furnace (right) and 3D rendering of the system (left).Differentpartssuchasrotaryfeedtrough,parabolicreflectorsandportscanbeobserved.................79
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Figure55.Conceptualdesignof thehighpressure setup including themain componentsand thesupport...................................................................................................................................................80
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1. ABSTRACTTheFaXToRinitiativehasbeeninitiatedfromtheinterestandsupportofaclusterof
Spanishscientistscoveringawiderangeofdisciplinesfromfundamentaltoapplied
research.Oneofthekey issuesthatmotivatetheseresearchers isaccessingtothe
internal microstructure of their problemsubstances and investigating about the
dynamicprocessesoccurringinthem.SynchrotronXrayimagingis,nowadaysoneof
themostusedtechniquesforthispurpose.Ontheonehand,fastXrayradioscopy
allow understanding dynamic processes taking place in short times (mili and
submilisecond range) combining the fast imaging acquisitionwith the penetrating
powerofXrays,althoughwiththelimitationofa2Dimagesequence.Ontheother
hand, synchrotron tomography provides a way for visualising and analyzing the
threedimensionalinteriorstructureofrealobjectsnondestructivelyandwithahigh
spatialresolution. Inrecentyearsdifferentbeamlines inEuropehavefocusedtheir
developments towards3D+tor4D techniques (combinedwith in situapproaches)
with the objective of achieving a new technique, real time tomography,which
combines3Dspatialresolutionsoffewmicronsandtemporalresolutionsbellowthe
second.
This proposal is oriented to the creation of future fast imaging beamline at Alba
synchrotron which may cover the demands, not only of the Spanish scientific
community but also the European ones. The instrument is conceived as amulti
purpose system thatmay allow the realizationofdiverse imaging techniques that
willbeexplainedanddeveloped in thisproposal. In theproposalwealsoconsider
the future development of the instrument aiming at extending the number of
availabletechniquesintheincomingyears.
Webelievethatthecreationofanimagingbeamlinewithpossibilitiesofdeveloping
3D, insitu, and real time studies constitutes a strong opportunity for Alba
synchrotron for offering an alternative to a highlydemanded technique for
europeanusers.
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2. INTRODUCTION
2.1. ImportanceofXrayimagingandtomography
Several fieldshaveexperienced importantprogressover the lastdecadeswith the
development of threedimensional (3D) characterization techniques. The
understanding ofmaterials, animals, fossils, objects, etc. has gradually increased
aided by the development of methods that provide as complete and unbiased
descriptionofmicrostructureaspossible.Fromthe3Dmicrostructure,quantitative
information in three dimensions can be retrieved usingmethodologies based on
image analysis techniques. 3D data provides access to some very important
geometricandtopologicalquantitiessuchussize,shape,orientationdistributionof
individual features and that of their local neighbourhoods, connectivity between
features and network, composition, etc. Some of these quantities cannot be
determinedapriorifromclassicalstereologicalmethodsthatuseonly2Dimagesor
atthebestonlysemiquantitativelyestimationsarereached.Besides,thepossibility
toconductinsitu3Dcharacterizationofdynamicexperimentsisexpandingourview
on fluid flow inporoussystems,metalmicromechanicsor thearchitectureof food
texture,tonameafew.
Experimentalmethods that enable 3D characterization have undergone dramatic
improvementsinthepastdecadedue,inlargepart,toadvancesinbothcomputing
powerand visualizationandanalysis software thathavebeenenabling factors for
both the acquisition and interpretation of these massive data sets. Several 3D
characterization techniquesareavailable forscientists that span from theatom to
the macroscopic engineering or natural components. Some examples are Atom
ProbeTomography(APT)[1],electrontomography[2,3],neutrontomography[4,8],
3DXraydiffraction(3DXRD)[5,8],serialsectioning(OM,FIBSEM,3DEBSD)[6,7],X
ray tomography (XCT) [812],amongothers.Thevarietyof3D imagingmethods is
large, and theydifferby theprobing rays theyuse,by thephysicalquantity they
measure and by themathematical reconstruction technique they are based on.
Figure1showssomeofthecommonlyusedcharacterizationmethodswhichcovera
range of different resolutions and sample sizes (beginning and end of the bar
respectively)overnineordersofmagnitude[11].
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Figure1.Tomographicmethodsspanningover9ordersofmagnitude[11].
2.2. VirtuesofXraytomography
Absorption contrastXray computed tomography (XCT) isprobably themostwell
known 3D xray imagingmethod. In thismode it ispossible todetectdifferences
between xray absorption coefficients of different phases, provided they are
different enough. This technique can be carried out with lower energy beams
available on desktop instruments (for relative low density specimens). Indeed,
commercial XCT instruments with resolution in the order of micrometers, have
proliferated rapidly in recent years. Synchrotron radiation, on the other hand,
provides the largest number of experimental options for tomography based on
imaging (absorption tomography, phasecontrast tomography, holotomography,
laminography, nanotomography, aborption edge tomography) as well as using
diffraction (3D Xray diffraction microscopy 3DXRD, diffraction contrast
tomography DCT), among others. One reason is the extraordinary brilliance of
thirdgeneration synchrotrons, many orders of magnitude higher than that of
conventional Xray tubes. This characteristic allows the possibility of selecting a
narrowenergyband(usingmonochromators)andstillhavingasignificantfluxoruse
pinkorwhitebeamsifhigherfluxesarerequired,dependingontheapplication.Also,
the high coherence of synchrotron Xray beam allows us to exploit the phase
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interactionwithobjectsof this radiation.SXCTalsoprovidesa rangeof resolution
(Figure1) thatcanbeused tostudy the3Dmicrostructureand featuresofawide
varietyofmaterialsandhavebeenasubjectofstudyindifferentpublications[9,13
22]. Other virtues are deep penetration, nondestructiveness (which provides
temporal evaluation possibility), simple sample preparation and the possibility to
providechemicalinformation.
2.3. DevelopmentofSXCTinthelastdecades
Synchrotron Xray computed tomography (SXCT) has experienced a rapid
developmentoverthe last15yearsachievingconsiderable improvements inspatial
andtemporalresolution,volumereconstructionspeedand3Dmethodsofanalysis
thatallowsquantitativeanalysisofthetomographicdata.AsaconsequenceXCTand
SXCT areprogressivelybecoming an accepted tool for scientists and industry as a
reliableandprecise3Dcharacterizationtechnique.Thisstatementcanbeconfirmed
if we observe the scientific production directly related to synchrotron
microtomography during the last decades (Figure 2). The consolidation of the
techniqueisbothintermsofindexedpublicationperyearandvisibility(Figure2ab),
contributing directly to high impact scientific results (Figure 2b). In parallel, the
particular interestof thescientificcommunity inusingSXCT fordifferentpurposes
has leadtoabeamtimeoverwhelmingdemand inmostSXCTbeamlinesacrossthe
world reachinganoverload factorofnearly3 (higher inparticularbeamlines) ina
short time. Interestingly the comparisonwith theuseofdiffraction techniques at
synchrotron facilities reveals that relative productivity has become similar, as
scientificinterestontomographyhasgrownwithyears(Figure2c).
Regarding the scientific production of specific techniques, nanotomography (or
zoomtomography) and insitu 4D tomography are probably themost interesting
developmentsand,asaconsequence,twoofthemostusedtomographictechniques
for the scientific community,highly increasing thedemandof these techniquesat
thesynchrotrons(Figure2d).
AnotherimportantstrengthofSXCTistheversatilityofthetechniquedepictedinthe
multidisciplinary origin of the scientific production (Fig. 2e). This feature strongly
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contributes to the expansion of instrumental development and experimental
environmentsavailableatSXCTbeamlines.
Figure2.Scientificproductionconsideringsynchrotrontomographyoverthelast20years(a)Number
ofindexedpublications(b)Citesperyear,totalnumberofcitesandhindexforsynchrotron
tomography.(c)Scientificproductionconsideringsynchrotrontomographyanddiffractionoverthe
last20years.Thenumberofpapersisnormalizedtothemaximumnumberofpaperperyear.(d)
Relativenumberofpaperfordifferentspecifictomographictechniques(normalizedtothemaximum
numberofpaperperyear).(e)Publicationbysubjectforsynchrotronmicrotomography.Source:Web
ofScienceandScopus.
(e)
(d)
(c)
(b) (a)
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2.3.1. 4Dtomography
4D tomography refers to the possibility to perform a repeated series of 3D
topographies at sequential time lapses, providing information about the
microstructureevolution.This isoneofthemostattractivefeaturesofSXCT.Asan
exampleinmaterialscienceandexperimentalmechanics,theevolutionofstructure
canbe very importantduringmanufacturing [9], service lifeand inunderstanding
failuremechanisms[17],aswellasinunderstandingtheprocessofbreadmaking[28],
and is proven to be a valuablemethod in other areas, too. One very important
characteristicof4Dtomography isthetemporalresolutionthatcanbeachieved in
the measurement of one tomogram. In many cases, fast acquisition time are
necessary, normally at expenses of spatial resolution;while in others,when the
microstructure is quasistatic, longer measurement times with better spatial
resolutionareaffordable.
4Dtomogramscanbecarriedout inseveralwaysdependingon itsapplication.Ex
situapproachescanbeused for longtermtreatmentappliedtothesamesamples
providedtheydontneedtobecutfortomographicmeasurements.Someexamples
ofthatarecorrosionstudies,exposuretomoistureandcertainheattreatmentsthat
cannotbecarriedout insitu. Insomecaseswhen thesamplesare larger than the
field of view (FOV) of the detector the evolution of features are evaluated on
differentsamplesatdifferentconditions (becausespecimenshavebecut)and the
extracteddataaretreatedinastatisticalwayasfunctionoftime.Anexampleofthat
is longterm creep studies,manufacturingdefectsormicrostructural changes,etc.
Perse,4Dtomographyprovidestheevolutionofaspecificfeatureasafunctionof
time,which insomespecificcasescanbe linkedtoanothervariable (temperature,
pressure,strain,etc.).Thecombinationof4Dtomographywithinsitudevicesopens
upothernewpossibilitiesandfieldsofresearch(seesection2.3.2).
Surfaceobservationcanbeausefulapproach,butinmanycasesstructuralchanges
occur in the bulkmaterial at hidden view. 4D tomography allows following the
structure evolution nondestructively in 3D manner. A significant amount of
informationcanbeobtainedonly fromvisualizationoftheeventsthatoccur in3D
over a time lapse, but in most of these cases quantitative information is also
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required. Increasingly,thenewtrend istoobtainquantitative informationfrom3D
and 4D tomography. This allows to understand the heterogeneities of the
microstructurein3Dand4D,andtoevaluatethepredictivecapabilityofanalyticalor
numerical models to describe behaviour and predict the kinetics of a certain
mechanism. To that end, several approaches for quantitative analysis are been
developed, suchasdigital volume correlation (DVC) [9,23,24],3Dparticle tracking
(3DPT)[9,25,26],howevertheirapplication isstillscarce.Itseemsnaturalthatwith
the increase inapplicationsthesemethodsornewoneswillbecomemoreefficient
and with improved accuracy. Recently commercial codes have become available
whichwillsurelyacceleratethedisseminationofthetechniqueeventotheindustry.
2.3.2. Insitutomography
Another approach is to carry out insitu studies in devices that are specially
developedforthatpurpose.Initially,theyweredevelopedbytheusersandbrought
tothebeamlinefortheexperiment,butthisalsocreatescompatibilityproblemsand
leadtoimportanttimelossesduringthebeamtimesonowadaysitiscommontofind
someofthesedevices(miniaturizedfurnaces,heatingorcoolingstages,tensileand
compression rigs, etc.) at the synchrotron beamlines available for the users.We
believe that an important asset for any tomographybeamline is thepossibility to
carryoutinsituexperimentsofdifferentkindusingspecialdevicesthat,atthesame
time, must be flexible in their configuration according to the high variance of
applications. Inouropinion,theproposedbeamlineshouldprovidetheuserssome
ofthesedevicesfor insitutesting,namelytensileandcompressiontestingrigwith
temperatureregulation,ovensand/orheatingstages.Someotherlesscommonbut
emergingdevicesarepressureanvils,hightemperaturedilatometers, infusion rigs,
fatigue testing rigs, corrosion cells, etc. Of course some of them could even be
combinedtoprovideanevenbroaderspectrumoftesting.
TomographictemporalresolutionisanissuestilladdressedbyonlyafewEuropean
synchrotrons,while inotherstheacquisitiontime isstill intheorderofhours.The
increase in temporalresolution isopeningupasetofpossibilities for tomographic
imaging applications that cannot be studied easily by othermeans. Considerable
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improvementshavebeenmadeinrecentyearsbycombiningtheveryintensewhite
(or pink) beams at synchrotron sources with a new generation of highspeed
camerasandnewtypesofscintillators.Timescalesforonetomographyisnowadays
intheorderoftensofmilisecons[27],allowingstudiesinmanydifferentfieldssuch
as food (breadmakingorbeer foam) [28,29]or inmaterialscience forcoarsening,
melting,solidificationofsemisolidmetals,aswellasdamageassessment.
2.4. Scopeofthisproposal
Thisproposalmobilizestheexpertisefromspecialistsfromdifferentfields(material
science and engineering from polymers to nickel superalloys, bioscience, food
science,earthscience,palaeontology,volcanology,metrology,etc.) topropose the
design of an Xray imaging beamline that provides a high resolution tomography
instruments that will permit to carry out different modalities (absorption,
absorptionedge, phase contrast and holo tomography) with optimum temporal
resolution with expected times per tomography below 1 second. Except for
absorption mode (without considering the exceptional expected speed at the
beamline) theother3 lastmentioned tomographic techniquesarenotavailable in
conventionallaboratorysources.Ofcourse,itcouldbealsopossibletocarryoutfast
radiography experiments, over 500 images per second, in those caseswhere 3D
resolvingpower isnot required.Thebeamline concept is completedbyproposing
different insitudevices thatwillbeavailable forusers. In this field, it isbecoming
clearthat,allowingtheobservationofthe interiorofasamplewithoutrequiringa
specific (andpossiblybiasing)preparationprocedure,Xraytomography isthebest
way to obtain reliable information on themicrostructure and its evolution, also
underdifferentloadings(e.g.mechanicalorthermal).
Considering the versatility of the instrument, the combination of different
tomographic techniques and the availability of insitu devices make this future
beamlineattractiveforalargenumberofpotentialusersfrommanydifferentfields,
which makes SXCT an essential technique in a synchrotron. Such tomographic
beamlinewillprovideavaluableasset to thescientificcommunity thatwillattract
researchers frommany different areas not only from Spain but from the rest of
Europe.
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3. THESPANISH(ANDEUROPEAN)USERCOMMUNITY
3.1. CurrentpanoramaofSXCTinEurope
In Europewe can find 8 different synchrotronswith beamlines oriented to Xray
tomography(softXraymicroscopy,nanotomographyandnonimagingtomography
difraction, fluorencence,etc.havenotbeen included in this selection).Figure3
show their location in Europe (3 in Germany, 2 in France, 1 in UK, Italy and
Switzerland). According to this list, other synchrotrons in Europe have not been
considered (e.g. Alba) since they do not have any beamline dedicated to Xray
tomographyinthetermspreviouslymentioned.
Figure3.MapofEuropeincludingthelistofEuropeanSynchrotronswithavailabletomographic
techniques.
Complementarily, Table 1 lists the name of these beamlines, together with the
availabletomographictechniquesandtheenergyrange.Fromtheseresultswecan
state that a total of 12 beamlines in Europe are currently dedicated to Xray
tomography and have developed different tomographic techniques.Nevertheless,
theyarenotmany ifwecompare themwithdiffraction,XANES,orXASbeamlines
presentinEuropeinthedifferentsynchrotrons.Actuallytheoverloadfactorofthese
beamlines is,byfar,higherthanotherstypesoftechniquesandtherefore itwould
be interesting to complete the current European offer of SXCT with a new
tomographic beamline at Alba. It is also important to mention that only two
beamlines have oriented their developments to fast tomography. In this sense
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TOMCAT (SLS) [27] and ID19 (ESRF) [30] are currently the leaders in this aspect
reachingupto20tomogramspersecond.TheFaXToRproposalaimsatofferinga
new beamline for the realization of Fast Xray Tomography and Radioscopywith
specialemphasisforinsitustudiesand,thus,completingthecurrentofferforSXCT
inEurope.
Table1.XraytomographyimagingbeamlinesavailableinEurope
Beamline Synchrotron Tomographytechniques ENERGY(keV)
IMAGE ANKA
2D:microscopy,radiography,topography,andmicrodiffractionimaging
3D:tomographyandlaminographywithmonochromatic,pinkorwhitebeam(highcontrasttoultrafast)Notavailableforusersyet
765
TOPOTOMO ANKA WhitebeamXraytomography(submicrometer)Phasecontrastimagingwithgratinginterferometer. 640
BAMline BESSYII MonochromaticTomography(Si111andmultilayer),WhitebeamTomography. 590
I12JEEP DIAMOND WhitebeamXrayTomographyPhasecontrastimaging. 50150
DiamondManchesterImagingBranchline DIAMOND PinkTomographyandMonochromaticTomography. 830
SYRMEP ELETTRA MonochromaticTomography(Si111)WhitebeamTomography. 835
ID16ANanoImagingBeamline ESRF NanoTomography 17.033.6
ID19Microtomographybeamline ESRF
MicroTomography,phasecontrast,holotomography(res.:0.330m).Fasttomography(fewsec.).
DiffractionTopography6.0100.0
IBL(PE05) PETRAIIINanoTomographyMicroTomography
(Absorption&PhaseContrastTomography)550
HEMS(P07) PETRAIII XRD,SAXS,3DXRD,Tomography with1mfocus(basedonabsorptionandphasecontrast) 30200
TOMCAT SLS
AbsorptionbasedTomographicMicroscopy;PropagationphaseContrastTomographicMicroscopy
DifferentialPhaseContrast(DPC)Tomographicmicroscopy
AbsorptionandphasecontrastnanotomographyUltrafasttomographicmicroscopy.
845
PSICH SOLEIL MonochromatichighenergyresolutionTomographyMonochromatichighfluxTomography.
15100keVwhitebeam(lowenergyfiltered)
1550keVmonochromatic
3.2. PotentialusersinSpain
InthepreparationofthisproposalwescannedtheinterestoftheSpanishscientific
communityinthistechniquebycarryingoutamailingsurvey.Asaresultofthispoll,
morethan25Spanishresearchgroupswereinterestedinthistechniqueanddecided
to support thisproposal.Table2 lists thegroups, the institutionand the research
interestobtainedfromthementionedsurvey.Oneofthemaincharacteristicsofthis
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supportingclusteristheirmultidisciplinarityconsideringthehighvarietyofresearch
interests they represent,which actually provide an addedvalue to this proposal.
Figure4 shows thedistributionwithin the Iberian territoryof the groups listed in
Table2.
Oneof themainconclusionsof the survey is thatwebelieve there isa significant
criticalmass of groups thatwill be demanding this technique at Albawhen the
beamline isready.Additionallyweareprettysurethatmanyotherresearchgroups
andcompanieswillbecomeuserswhentheycouldseetheresultsobtainedbyother
groups/colleagues.Finallywehavetoconsiderthatitisexpectedthatthisbeamline
willbealsorequestedbyEuropeanusersasitwillbeanalyzedinnextsection.
Table2.SpanishresearchgroupssupportingtheFaXToRproposal
Leader Group/Institution Interest
J.GmezBarreiro U.Salamanca HighpressureandtemperatureofgeologicalmaterialsR.CamposEgea CIEMAT GeologicalmaterialsJ.CostaBalanzat U.Girona CompositeMaterials
J.C.Glvez UPolitcnicadeMadrid FractureofSteelsandCementbasedmaterialL.E.Hernndez U.AutnomadeMadrid Vegetalmaterials
J.Snchez (IETccCSIC) Structures,concreteM.Lanzn U.PolytechnicalCartagena Buildingmaterials,stone,patrimonialbuildings
D.A.CendnFranco U.PolytechnicalMadrid MetallicmaterialsF.SanJoseMartinez U.PolytechnicalMadrid Soilstructure
F.A.Lasagni CATEC CompositematerialsandmetalalloysV.GomezRuiz U.Oviedo GeomaterialsG.GarcsPlaza CENIM MultiphasemetallicmaterialsJ.A.Yage U.Zaragoza Metrology,Imagetreatment
L.FrancoFerreira Aimen NDT,dimensionalmetrology,materialcharacterizationA.Mendikute IDEKO Imagetreatment,nondestructivetestingJ.vanDuijn U.CastillaLaMancha SolidOxidesbateriesV.Amig U.PolitcnicadeValencia Titaniumalloyscharacterization
C.Capdevila CENIMCSIC Febasedalloys,steelsL.Galdos U.Mondragon SuperPlasticFormingofAluminiumSheets.P.Bravo U.Burgos HPDCofMgalloys,polymers
J.C.SurezBermejo U.PolytechnicalMadrid Structuralhybridmaterials,adhesivos,damagingM.A.RodriguezPrez U.Valladolid Cellularmaterials,Xraytechniquedevelopment
D.Val GRUPOANTOLINIRAUSA,S.A. MagnesiumandaluminiumalloysR.ArenasMartn U.ComplutensedeMadrid HighpressuremetamorphicrocksF.J.SierroSnchez UniversityofSalamanca Micropaleontology
SrenJensen UniversityofExtremadura PaleontologyGroup
I.Rosales SpanishNationalGeologicalSurvey Geology
G.GarcsPlaza CENIM MultiphasemetallicmaterialsA.lvarezValero UniversityofSalamanca Volcanology
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J.R.MartnezCataln UniversityofSalamanca TectonicsygeophysicsA.RodrguezBarbero UniversityofSalamanca Renalandcardiovascularphysiopathology
P.Ayarza UniversityofSalamanca Geophysics:SeismicyMagnetismsJ.MBentezPrez UniversityofSalamanca microstructurecharacterization
E.GonzlezClavijo SpanishInstituteofGeologicyandMines Tectonicsandnaturalresources
M.SurezBrrios UniversityofSalamanca CrystallographyandMineralogyC.Gonzlez IMDEAMaterials Fibrereinforcedpolymers
T.PerezPrado IMDEAMaterials LightmetalalloysJ.Molina IMDEAMaterials MicroandNanomechanicsmetallicF.Sket IMDEAMaterials FRP;lightmetalalloys;steels
Figure4.GeographicdistributionofthesupportingclusterintheIberianterritory.
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4. RELEVANTSCIENTIFICCASES
Xrayradiographyandtomographycanbeappliedtoseveralscientificandindustrial
fields, therefore it isnoeasy toorganize the researchareas inwhich tomography
wasor couldbe applied.Wehave subjectively selected some research categories
whichinsomecasesthescientificcaseswilloverlapothercategories.
4.1. MultidisciplinaryFasttomographyandradiography:insitustudies
Inmanyresearchareas,evolutionofthestructureisofprimeimportance.Asanon
destructivetechnique,XrayCTcanprovideaverydetailedpictureoftheevolution
of the structure/damage through a certain processes applied to a material.
Furthermore the opportunity to host environmental stages means that
structure/damage canbe followed in situunder a rangeofdemanding conditions
representative of those experienced in reality. Consequently SXCT enables the
quantificationofaverywiderangeofstructuralchangesanddamagemechanisms.
Someexamplesarepresentedbelow.
4.1.1. Bubblenucleationandgrowthcharacterizedbyultrafasttomography
The use of Xray tomography brings the possibility of performing detailed
characterizations of the cellular structure of foam specimens in three dimensions
(3D)although ingeneraltomographiesareacquired instaticconditions. Inevolving
systemsitwouldbeexpectedthatthehighnumberofprojectionsandtherelatively
long exposure time neededmay output blurred tomographies. Thanks to the last
developmentsatsynchrotronbeamlinesnowadays it ispossibletocarryouttime
resolved Xray tomography studies reaching time resolutions unimaginable a few
yearsago[29].
This study uses synchrotron timeresolved Xray tomography to understand the
effectofnanoparticlesonthebubblegenerationnucleationanditslaterevolution
growthofa reactivepolyurethane foam formulation.The time resolutionof the
performed experimentswas 156ms per tomographic scan (near to 10Hzmicro
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tomography) and a total number of 90 tomographies during the foaming process
whereacquired.
Acommercialbicomponentpolyurethane(PU)formulationfromBASFwasselected
for this investigation. The turbulentmixing of two liquids (polyol and isocyanate)
promotesasimultaneousblowingandgellingreactionthatresultsintoasolidfoam.
The density of the foam in a free foaming process is 52 kg/m3. The nucleating
nanoparticleselectedforthisinvestigationwashydrophobicfumedsilicaandtothis
end3%wt.ofsilicananoparticleswereinitiallydispersedfor120sintheisocyanate
compound.
Aspecificsetup(Figure5)wasdevelopedtomixtheisocyanate(neatformulationor
the blend containing the particles)with the polyol in the same rotating table in
whichthesequencesoftomographiesweretaken.Thisallowsobtaininginformation
fromthe initialstagesoftheprocess.Thepolyoland isocyanatecomponentswere
placed inadedicatedminiaturecylindricalmold (h=40mm,=12mm, thickness=75
mKaptonwalls),attachedtothetomographyrotatingtable.Amotorizedminiature
stirreratthetopwasautomatically immersed inthe liquidsandstirredthemixture
for15 seconds at1500 rpmpromoting theblowing andpolymerization reactions.
Thetomographyscansstarted10secondsaftertheendofthemixingprocess.
Figure5.Detailofthestirringheadoverthekaptonmouldcontainingtheisocyanateandpolyol
blendsbeforethemixingprocess.
Xray tomographic experimentswere performed at the TOMCAT beamline of the
SwissLightSourceatthePaulScherrerInstitute(Villigen,Switzerland).Theultrafast
endstation incorporates a PCO.Dimax camera,which acquires and transfers data
ordersofmagnitudefasterthanCCDcameras.TheopticswerecoupledtoaLuAG:Ce
Foaming mould
Stirrer to mix the components
Rotary stage for the tomographic
experiments
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100mthickscintillatorscreen.Magnificationofx4intheopticalmicroscopelenses
wasselectedforthisexperiment.Thiscorrespondstoapixelsizeof3.23.2m2and
a field of view of 6.446.44mm2.Monochromatic Xrays (20KeV, no filter)were
used; generating300projections capturedover180of rotationwith a total scan
timeof156ms.Spantimeof2.5swasusedinbetweenscans.Reconstructionswere
performedbyusingtheGRIDRECalgorithm[31,32]coupledwithParzenfilteringof
thesinograms.
Reconstruction of the tomographic scans allows visualizing, in 3D, the cells
nucleation and growth processes from the early stages in both studiedmaterials.
Figure 6 shows the corresponding 3D renderings for four selected instants (9.8s,
21.7s,26.3sand32.6s.)duringthefoamingprocess. It ispossibletoappreciatethe
highercellsizeintheneatPUformulationandthesmallersizetogetherwithamuch
higherdensityofcellsinthefoamednanocompositecontaininghydrophobicsilica.
Figure6.Volumerenderingatdifferentinstantsforthetwoexaminedmaterials
(TOP:purePU;BOTTOM:PUwith3%wt.nanosilica)at(a)9.8s,(b)21.7s,(c)26.3sand(d)32.6s).
Theanalysisofthetomographicsequencesallowsdeterminingthenumberofcells
percubiccentimetreandtheaveragecellsizeevolution.Figure7,left,showsthecell
density evolution during the foaming process. The results show that the cell
density increases linearly during the first 1015 seconds and subsequently slows
downwithtime. It isalsoclearlyobservedthatthenucleationdensity ishigherfor
thecompositionwith3%wt.ofsilicananoparticlessincethesefillerscouldfacilitate
bubbles formationat solid/liquid interfacesdue toa freeenergybarrier reduction
[33].Ontheotherhand,theexperimentalresultsforthecellsizeevolutionwithtime
(a) (b) (c) (d)
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by several authors for the initial bubble radius evolution [34,35]. Bubble growth
stabilizationisnotobservedandthemodellingdoneisthenvalidinourstudysince
the resultspresented here only focus on the first 50s of the expansion. It is also
possible to observe that average cell diameter keeps constant in the very early
instants (t
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allowing acquisition times of a complete tomogram in less than one secondwith
voxelsizesdownto~1m[42].
c) The applicability of phase contrast tomography to determine the internal
architectureoflightalloysformedbyphaseswithverysimilarattenuationsuchas
Tialloys,AlSiandAlMgSialloys[4345].
d) The exploitation of Kedge subtraction technique to identify concentration
variationsofdifferentaluminidesinAlcastalloysduringthermaltreatments[46,47].
e) The achievability of subm resolution to reconstruct the architecture of
multiphaseAlandTialloys[44,47,48].
Cast AlMgSi alloys are potential candidates to be used in the automotive and
aerospace industries [49]. The investigation of the kinetics of solidification is
necessary to understand how casting parameters, such as cooling rate and
temperature gradient in the melt, affect the development of the internal
architecture of alloys and consequently determine their resulting mechanical
properties.TheformationandtheevolutionofthemicrostructureofanAlMg4.7Si8
alloy were investigated by in situ synchrotron tomography (SXCT) during
solidification[38].TheexperimentwascarriedoutattheID15AbeamlineoftheESRF
usingapinkbeamandatotalscanningtimeofabout15sforeachtomogram.SXCT
wasperformedeveryminute,whileamoltensamplewassolidifyingatacoolingrate
of5K/min.
Figure 8 shows reconstructed tomographic slices extracted from the in situ
solidification experiment of the AlMg4.7Si8 alloy. The experiment allowed
determiningthesequenceandtemperatureofformationofthedifferentphases,as
wellastheirlocationanddistributionduringsolidification.
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Figure8.ReconstructedtomographicslicesobtainedduringinsitusolidificationofAlMg4.7Si8atthe
temperaturesatwhichconsecutivesolidificationofthedifferentphasesisobserved,[38].
Rendered3DimagesoftheAldendritessolidifiedatdifferenttemperaturesduring
cooling are shown in Figure 9a) to d). The colours represent theGauss curvature
between0.005m2and0.005m2,whilethegreypartsareoutofthisrange.Figure
9e)toh)showthedistributionofthemeanandGausscurvaturesofthesurfaceof
the Al dendritic structure at the different stages (temperatures) of the
solidification process. The characteristicmorphologies for the axes and for each
quadrant are indicated schematically Figure 6e). It can be seen that twomaxima
emergeduringsolidification:oneclosertotheoriginrepresentingslightlysaddlelike
shapes,whichare related to thebasesand sidesof the secondarydendriticarms,
and another in the positivepositive quadrant representing spheroidlike regions
owing to the secondary dendrite tips. This indicates that themorphology of the
dendrites during cooling is characterised by coarsening,which is a simultaneous
processofgrowthandcoalescenceofthesecondarydendritearms,similarlytothe
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caseofisothermalcoarsening[50].Asthesolidificationadvances,thegrowthofthe
secondarydendriticarmsbecomesasymmetric,thetipsgrowwithahigherratethan
thebases,resultinginadropletlikeshape,wherethetipsofneighbouringarmscan
coalesce[50,51].
Figure9.a)tod):rendered3DimagesoftheAldendriticsolidificationatdifferenttemperatures
duringcoolingofanAlMg4.8Si7alloyobtainedinsitubySXCT.e)toh):distributionofthemeanand
GausscurvaturesofthesurfaceoftheAldendriticstructureatthedifferentstagesofthe
solidificationprocess.[38]
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4.1.3. Understanding explosive volcanoes: risk evaluation through
morphometricanalysisofbubblesandcrystalsinlava
About500millionpeopleare livingnearactivevolcanoesand thereforea reliable
evaluationofthenaturalriskinthoseareasisofprimaryimportance.Thepotential
ofexplosiveeruptionhastobedeterminedonthebasisofquantitativeevaluationof
thephysicalprocessesoccurringatcertaindepth in thevolcanicsystem.Access to
those levels is restricted to erupted fragments and indirect measurement from
outside.Inthisline,quantitativemicrotextureanalysisofbotheruptedclastsandin
situmeltingexperimentshasrecentlybecomingthe focusofattentionofgeologist
andgeophysicist sinceexplosivepotentialofavolcanic systemappears tobevery
related to the degassing path ofmelt all through the ascending conduit [53,54].
Throughthedetailedanalysisofbubbleshapesandinterconnection,parameterslike
bubblecoalescenceandtexturalrelaxationareconnectedwiththephysicalresponse
ofmelts [55]. The socalled vesiculationprocesses inmagmasdeterminewhether
theeruptionbecomeeffusiveofexplosive,soboth insituexperimentsandanalysis
of selected natural samples are needed to advance in our knowledge on vesicle
nucleation, growth and coalescence, and their connection with permeability
evolutionofmelts[54].Adependenceofthemicrotexturewithmagmacomposition
has been known atmacroscopic level, but not completely understanding at the
microscopic detail. While basaltic composition seems to evolve towards non
explosiveeruptionasporosityincreases(Figure10,[53]),siliciccounterpartsareless
known,andhencemoreunpredictable[56].
Figure10:Bubblesize,wallthicknessandinterconnectionfrombasalticfoams[53]
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Particularlystrikingisthecaseofsiliciceruptionswhichseemstoalternatebetween
violenteruptionsandgentleones. Ithasbeendemonstratedthattheway inwhich
volatiles escape from the shallow part of the volcano conduit, determine such a
behavior[54].Onecriticalissueistounderstandhowbubblesnucleateandgrowin
response to decreasing pressure asmagma rises toward the surface. Synchrotron
microtomography analysis on Kilaueas pyroclast has showed the complexity of
bubblegenerationatdifferentpressuresduring2008eruption[56].Pyroclastswere
imagingatALSsynchrotronfacilityat20keV,200msexposuretimeand1400rotation
steps between angles of 0 and 180. Threemain pyroclastic typeswere found,
which depicted large bubbles (mm) surrounded bymicrometricthick haloes that
containsanelevatednumberofsmallisolatedroundbubbles(radius=2.5m35m,
Figure11A)D)[56]).
Figure11:Differentpyroclasticmicrotexturesfromsilicicmelts.Bubblesappearsegmented[56].
Themicrotexture found in thosepyroclastsrevealsahighdensityofsmallbubbles
withinthehaloes,pointingtonucleationratesrelativelyhigh,butwithlittletimefor
coalescence. This important fact support the ideas thatwater concentrations are
onlyhighenoughinthecloserangeoflargevaporbubblespriortoeruption[56,57].
The existence of a thin region around bubbleswheremeltwith dissolvedwater
occurs. It is an intimate result of preeruption and it is interpreted as a water
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reabsorptionback intomagmapriortoeruption.Thosetexturescouldalsobeused
totrackconvectivebehavioratamacroscalewithinthevolcano.
Recent developments include in situ investigation ofmagma vesiculation at high
temperature. Heating systems combined with ultrafast acquisition, like those
implemented inTOMCATbeamline(Figure12ab;[27,58])areofthemost interest
formelt foams research [59]but also in similarmaterialsone.g.managementof
nuclearwaste[60].
Figure12.(a)3Ddesignand(b)topphotographofthelasersystemmountedonTOMCATbeamlineat
SLS.Trangeis4001700C[58,59]
The application of this experimental system to the investigation of vesicles
development inacidmeltsatdifferent temperatures is showed inFigure13, [59].
Interestingly, shape and volume analysis reveals a connection of rigid and soft
behavior of bubbleswithmagma rheology [61], providing crucial parameters for
understanding how the viscosity ofmelts and gas overpressure during degassing
processes controlmagma ascent along volcanic conduits. This is crucial topredict
explosiveeruptionsinthosesystems[59].
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Figure13.ac3Drenderingofacidmeltatdifferenttemperatures(bubbles);d)bubblesize
distributionsatdifferenttemperatures;e)bubbleanisotropyandfractionversustemperature[59].
4.1.4. Foodscience:tastingthetexture
Thephysiochemical,functionaland insomecasesnutritionalpropertiesoffoodare
intimately controlled by its microstructure. The quantitative analysis of food
microstructure has become critical in order to understand the physical and
rheologicalbehavioraswellassensoryattributesoffoods.Foodprocessingarenow
changing toward to the microstructure level design and testing, and xray
microtomography is the technique of choice for visualizing those systems.
Microstructural elements such as air bubbles or cells, starch granules, protein
assemblies and food biopolymermatrices contribute greatly to the identity and
qualityoffoods[62,63].
Themicrostructureoffoodhasastronginfluenceovertheattributesofaproductas
evaluated by consumers. Many of those macroscopic properties are poorly
understoodbecauseoftheircomplexnature,derivingfrommultiple interactionsof
processesandfoodmicrocomponents[63].
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Example of that interconnection between microstructure and complex
physicochemical processes, and the profound impact of texture on the taste and
flavorquality isfoundmanyproducts likefruit[64,65],bread[28,66,67]andcoffee
[68] to name a fewwith a very high social and economic impact. Both fruit and
bakedproductsshare thestrongdependenceon theircellularstructure thatcould
beoptimized through appropriateddesignduring growth andproduction andwill
determine transport/distribution strategies and midlong term durability of the
product.Inthecaseofbread,3Dimagingthroughxraymicrotomographycombined
withfastacquisitionhasproventobeveryefficientwaytounderstandcellstructure
evolution during proofing time (Figure 14, [67,68]). These results can be used to
improvethedesignandproductionofnotonlybreadbutotherbiopolymericfoams.
Figure14.Evolutionbubblesinbreadduringproofing:(a)2Dimagesofhorizontalsections(diameter
9mm)extractedfromreconstructedvolumes(628x628x256voxels)(b)and(c)Voidvolumefraction
andaveragecellwallthicknessforthreedifferentdoughs[68].
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In the case of fruits, the microstructure determines mechanical and transport
properties of tissues. Therefore, a quantitative description of fruit tissue
components in 3D are critical, both to understand the properties and to develop
structure reliablenumericalmodelson them.Figure15 showsananalysisofSXCT
dataonfruittissuefromwhereimportantparameterswereobtained:cellwall,pore
network and cell size. These componentswere then used to design a numerical
model to run multiscale mechanics and mass transfer, thus providing a solid
frameworkforvirtualtissuegeneration,includingcellgrowthmodeling.Thisstrategy
provideaunique tool formoving fromgeometricdescription tophysicalmodelof
fruittissue[65].
Figure15.(upperleft)Synchrotronradiationtomography:phasecontrastslicesofthefruitcortexof
apple(left)andpear(right);cellwallsareindicatedbyarrows.(lowerleft)Modeled(a)against
measured(b)3Dgeometryofapplecortexcells.(Right)Theoxygenconcentrationprofileinsidecells
usingfiniteelementsimulations.Drivenforcewaspartialpressureacrosstheboundariesofthetissue.
Thepartialpressureandconcentrationinsidethetissuewasrelatedbytheuniversalidealgaslaw[65].
4.1.5. Ultrafast2DRadioscopyon cellwall ruptures to studymetal foam
stabilitymechanisms
ThirdgenerationsynchrotronlightsourcesdeliverapolychromaticXrayphotonflux
densityhighenoughtoperformradiographywithmicroresolutioninbothspaceand
time[6972].Therapiddevelopmentof imaginghardware,especially inthefieldof
CMOS sensors, and their continuously improving sensitivity now allows for
extraordinarily high recording speeds, with exposition times down to 1s for a
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considerable(atleast1020mm2)fieldofview.TheoptimizeduseofsocalledXray
inline phase contrast (due to the coherence properties of an Xray synchrotron
beam) allows for thebestpossible contrast forour cellularmaterial.Additionally,
radiation hard but highly sensitive and efficient single crystal scintillators such as
LuAG:Ce or YAG:Ce crystals are employed. This permits us to follow the overall
processand resolve insitunotonly slowprocesses (>1msexposure time) suchas
pore nucleation and growth, foam expansion or drainage, or simply observe the
overallfoamingprocess,butalsoveryfastones(1msexpositiontime)suchascell
wall rupture, bubble coalescence, rapid bubblemotions or oscillations. Figure 16
shows the improvement of time resolution for Xray synchrotron radioscopy on
metallicfoamsachievedinthepastyearsasreportedintheliterature[7176].
2000 2002 2004 2006 2008 2010 2012
100
101
102
103
104
105
1
0.1
0.01
1E-3
1E-4
1E-5
0.5 s
Stanzick, Foams & Emulsions, [16] Banhart, AEM, [17] Stanzick, AEM, [18] Garcia-Moreno, APL, [14] Rack, JSR, [15] Garcia-Moreno, ESRF MA 1134
Acq
uisi
tion
rate
[fra
mes
/s]
Year
1 ms
Cell wall rupture,Bubbles coalescence
Foaming behaviour,Process control
9.5 s
Fram
e in
terv
al [
s]
Figure16.EvolutionoftimeresolutionforinsitusynchrotronXrayradioscopyappliedtovisualize
metalfoaming.
Thestabilizationofmetalfilmsorcellwallsinliquidfoamsisakeyissueinmetal
foam science but still not fully understood. To investigate the nature of rupture,
experimentshavebeenperformed inwhich therewasasimultaneousdemand for
both high spatial and high time resolution. It was possible to observe the
coalescenceof twoadjacentbubbleswitha recording speedof105,000fpswitha
frame intervalof9.5s andeffectivepixel sizeof20m.Although the contrastof
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suchimagesislowduetotheshortexposuretimeandconsequentlimiteddynamics
oftheimages,itisclearlyvisibleinFigure17thatthecoalescenceoftwobubblesis
completed in~475sandthattheruptureofafilm lastsfor~380s, ifweconsider
theendoftheruptureasthepointwherethecontourofthenewbubblebecomes
straightbeforeitendsasconvex.
Figure17.SeriesofradiographsofanAlSi10+0.5wt.%TiH2foamat640Cextractedfromaninsitu
fastsynchrotronXrayradioscopicanalysis.Thecoalescenceoftwobubblesmeasuredwith9.5s
frameinterval(105kfps)canbeobserved.Dashedlinesindicatethecontoursofthebubblesand
arrowsindicatethecorrespondingrupturedcellwall.
Inthisexperimentsitwaspossibletodemonstratethattherupturetimeofafilmis
dominatedbytheinertiaofthefluidandnotbyitsviscosityasruptureoccurredso
fast [71]. Therefore, it could be demonstrated that stabilization by an effective
viscosityonly,whichwouldbeashighas=0.4Pas (ascalculatedbyGergelyetal.
[77])doesnotapplytometalfoamsofthetypeinvestigatedhere.Otherfactorssuch
as bubble size and alloy compositionmay influence the rupture time andwill be
studiedinfuture.
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4.1.6. Insitutomographyofcreepprocessofbrass
The efficiency of electricitygenerating plants in general and gas turbines in
particular increases with increasing service temperature, therefore requiring
components with sufficient hightemperature strength. The lifetime of such
components is usually restricted by creepinduced cavity growth leading to
unacceptablestrainsandfinallytofracture[52].
Synchrotron radiation microtomography provides new possibilities for a non
destructive determination of creep damage evolution in the bulk of samples,
comprising statistical analysis of cavity volume, shape, and orientation evolution
during insitu creep experiments. The results of the experiments enable a
quantitative description of the time dependence of cavity morphology and size
distributions.
FasttomographymeasurementsduringcreepwereperformedatID15Abeamlineof
theESRFusingahighenergybeam (~80keV)witha largebandwidth (~50%).The
acquisition time of a complete tomographic scanwas 3min [78]. The absorption
radiographswererecordedwithafastchargecoupleddevice(CCD)withaneffective
pixel sizeof1.6m. The tensile creep testwasperformed in aminiaturized creep
machineatconstantloaddevelopedforinsitutesting[78].
The cavities developed during the creep testwere quantified in 3D by fitting an
equivalentellipsoid toeach cavity. Figure18 shows the3D reconstructionsof the
sectionedvolumerevealingcreepdamageevolutioninthesample.
Figure18.Tomographicvolumesrevealingthecavitiesatdifferenttimesduringthecreeptest.
(a)initialcondition,(b)middleofthetest,(c)closetofracture.
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Figure 19 shows the shape evolution of the three largest cavities between the
reference state and the final state shortly before fracture. The evolutions are
representativeforthelargestvoids,whichusuallycontrolthefinalspecimenfracture.
Void evolutions indicate that creep cavities are relatively small and have nearly
ellipsoidalshape inearlierstagesofcreep.Asthematerialdeformstheygrowand
interactions among neighbors lead to coalescence. These interactionswere quite
significant for the studied brass alloy. A void can experience several coalescence
eventsduringthecreeptest.Thefirstcoalescencewassurprisinglydetectedalready
inthesecondarysteadystateregime.Notonlypairwisecoalescencesweredetected,
butalsothejunctionsoftripletsandquadruplets.
Figure19.Shapeevolutionofthethreelargestcavitiesexhibitingcoalescence.
Thedifferentstagescorrespondtothelargestporebeforecoalescence.
Thespatialorientationofacavity inthepresentwork ischaracterizedbytheangle
between themajorsemiaxisof theequivalentellipsoidand thezaxis (i.e. loading
direction). Figure 20displays a 3D graphof thepolar angleof cavitiesduring the
creep test for all cavities, revealing a smooth change of the cavity orientation
distribution.Suchachangeingeneralcavityorientationwouldindicatetheonsetof
enhanced cavity growth and linkupperpendicular to the stressdirectionwhich is
essentialfordamagingduringtertiarycreep.
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Figure20.Evolutionofthespatialorientationofcavities.
Thequantitativeanalysesperformedrevealedthatthedistributionofcreepcavities
with respect to size, shape, andorientationdependson the time the samplehas
been exposed to high temperature creep. The largest cavities were formed by
coalescence of two or more voids resulting in a complex shape. The cavity
population tended to be elongated perpendicularly to the loading direction. The
quantitativedataobtainedcanprovideabasisforavalidationofthedescriptionof
creepdamagebynumericalmethods.
4.1.7. Insitu tomography of damage development of carbonfiber
reinforcedcomposites
Therearemanyvariantsof fiber reinforcedpolymerssuchascarbonorglass fiber
reinforced;straight,wovenor3Dbraidedfiberreinforced;withfibersandparticles
as reinforce;withhollow fibersormicrocapsules for selfhealingmaterials;hybrid
carbon and glass, and the list goes on. The amount of variables thatmight be
changed in onematerial is huge. An example is the ply stacking sequencewhich
determinesthefailuremechanismsthatwillbeactivateduponloading.Inparticular,
carbonfiberreinforcedpolymers(CFRPs)arewidelyused instructuralcomponents
owingtotheirhighspecificmechanicalproperties.However,CFRPspresentseveral
failuremechanisms that coexist in the same laminate and, therefore, improved
understandingofdamageevolutionandeventualfailureisstillneeded.
InsituSXCTwasperformedon[+45/45/+45]sCFRPsubjectedtotensileloading.The
experimentswereperformedat the ID15Abeamlineof theEuropeanSynchrotron
RadiationFacility.A14bitFReLoN(fastreadoutlownoise)CCDcamerawithafield
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ofviewof1.2x1.1mmandaneffectivepixelsizeof(1.4mm)2wasused.Thespatial
resolutionwas about 2mm (the fullwidth at halfmaximum of the point spread
function).Apinkbeamwithmaximum intensityat~30keVwasused.Sixhundred
radiographieswererecordedbetween0and180resulting inatotalscantimeof
2min per tomogram. Ten scans were recorded at increasingly applied load. A
combinationofabsorptionandphasecontrastwasobtainedbyplacingthesampleat
~40mmfromthedetector.
The evolution ofmatrix cracking is shown qualitatively in Figure 21 for different
deformation steps. Each individual crack is shown in a different color. The initial
cracks grewwith the applied load, extending over thewhole section of the plies
beforefracture.Almostallthecracksbecame interconnectedathigh loads,sothat
themajorityof thedamagedisplaysasinglecolor.Noneof thepreexistingcracks
interactedduringdeformationwith theporesobserved in Figure21d).The crack
frontsandtheshapeofindividualcracksweregenerallyuneven.
The interlaminar crack growth shows a combination of cusp formation and
matrix/fibredebondinginfrontofthecracktip.Thecracksaresubjectedtoamode
IIshear loadingandcuspsdevelopperpendiculartotheprincipalstress,coincident
withtheloadingdirection.Asdeformationprogresses,cuspscoalesceandcontribute
tothepropagationofthecrack.
Themajor damagemechanisms and the sequence of occurrenceswere identified
and quantified. The extracted information can be used to validate and enhance
damagepredictionmodels.
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Figure21.Damagepropagationin45plies.
Differentcrackcoloursindicatetheirconnectivity(adaptedfrom[17]).
4.2. Materialscience
4.2.1. ResinmicroflowbyXraycomputedtomography
Highperformancecompositeshavetobemanufacturedinautoclavetoensurethat
theyareporefreebutthisleadstohighprocessingcostsandthereisalargeinterest
in the optimization of outofautoclave processing techniques. Vacuum Assisted
ResinTransferMolding (VARTM) isaveryappealingprocessdueto itsrelative low
cost and thepossibility toprocess largepanels. In thisprocess, the liquid resin is
infiltrated intoaplasticbagcontainingthe fiberpreformthat layonarigidmould.
The infiltration is assisted by the application of vacuum.However, the resin flow
through the fiber fabric is very complex and the key parameters that control the
nucleation,growthandcoalescenceofporesduringinfusionarenotwellunderstood.
Inaddition, the resin flow in the fabric takesplaceat twodifferent length scales:
macroscopic resin flowbetween the fiber towsprogresses rapidlywhilemicroflow
withinthefibertowsoccursatlowerspeed.Theinteractionbetweenmacroflowand
microflowisknowntobeacriticalfactorcontrollingthedevelopmentofporositybut
itisverydifficulttoanalyzeexperimentally.
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To provide the experimental evidence necessary to understand resin flow during
VARTM,aminiaturizeddevicethatreproducestheconditionsofVARTMprocesswas
developedand,at thesame time,allows tostudy the infiltrationatbothscalesby
meansofSXCT.Tothisend,highresolutionSXCTwasperformedatthefiberscaleto
analyzeinsituthemacroandmicroflowbehaviorandthedefectformationduring
the infusionprocess.TheexperimentswereperformedattheP05beamlineofthe
DESYSynchrotron.A14bitCCDcamerawitha fieldofviewof3.8x1.9mmandan
effectivepixelsizeof(1.25mm)2wasused.Thespatialresolutionwasabout2mm.A
monochromatic beam with 25 keV was used. Nine hundred radiographies were
recordedbetween0and180resultinginatotalscantimeof~2hspertomogram.
Due to the largemeasurement time the liquid flowhas tobe stoppedduring the
measurement. This could be avoided with a fast tomography setup and would
providerealtimeinformationaboutinfiltrationmechanisms.
Figure22showstheexperimentalsetupattheP05beamlineatDESYSynchrotron.
Theliquidisinfiltratedfromthetop(inlet)andthevacuumisappliedatthebottom
(outlet).Thefibertowspecimen,placedinavacuumbaginsidethePMMAtubewas
scannedbyXraysduringinfiltration.
Figure22.Experimentalsetuptostudyinsitutheinfiltration
processattheP05beamlineofDESYSynchrotron.
Figure 23 shows a reconstructed volume and a crosssection obtained by SXCT
showing the flow front (macroflow) around the tow and themicroflow inside the
tow.Thisuniqueexperimentalsetupprovidesthe informationtoanalyzetheresin
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flow in3dimensionsduring infiltrationatboththemicroscaleandthemacroscale,
aswellastoassessthedifferencesinpermeabilitybetweenbothregimes,beingthe
former several orders of magnitude lower than the latter. Moreover, the
experiments shows the conditions that give rise to regions that might remain
partially infiltratedduetotrappedairbubblesortodifferencesbetweencapillarity
andresinpressure,leadingtolowqualitypanels.Basedonthesedata,itispossible
to design optimized VARTM strategies to improve the quality and reduce the
processingcostofadvancedstructuralcomposites.
Figure23.(a)Crosssectionofthescannedfibertowspecimeninthevacuumbag.Wetglassfibersare
surroundedbythelightergreycolor.(a)3Dreconstructionoftheinfiltratedtow.
4.2.2. 3DmultiphasenetworksprovidinghightemperaturestrengthtoAlSi
pistonalloys
CastAlSialloysarewidelyused inautomotivecomponentssuchascylinderheads
andpistons.Thetemperatureriseinthecombustionchamberofadieselenginecan
reachup to~300400Cand, therefore,high temperaturestrength isan important
requirement forpistonalloys.Thehigh temperature strengthofcastAlSialloys is
providedbyatransferofloadfromtheductileAlmatrixtorigidandusuallyhighly
interconnected3DnetworksofeutecticSi.However, ifcastAlSialloysaresolution
treatedabove500C,theeutecticSirapidlydisintegratesandspheroidizesreducing
thestrengthofthealloy[79].Thelossinstrengthcanbereducedbytheadditionof
transitionelements such asNi andCu that form thermally stable rigid aluminides
[80,81].ThereasonsfortheimprovementofmechanicalpropertiesofAlSialloysby
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additions of Ni and Cu are stillmatter of scientific investigationswith important
technological implications.TheeffectofdifferentadditionsofNi,CuandFeonthe
hightemperaturestrengthofcastAlSipistonalloys is investigatedwithrespectto
the microstructural architecture formed by the aluminides and the eutectic Si.
Therefore, absorption and phase contrast synchrotron microtomography was
appliedtosamplesofthealloysAlSi12,ASi12Ni,AlSi12Cu5Ni1andAlSi12Cu5Ni2 in
ascastconditionandaftersolutiontreatmentusingtheID19beamline.
Figure24showsthelargestparticlesoftheeutecticSiandofthealuminideswithin
theconsideredvolumesforthestudiedalloysafter4hsolutiontreatmentat490C.
Thetomographicresultsshowthatthe interconnectivityoftheeutecticSi ishighly
conserved after the solution treatment for the aluminidecontaining alloys (Figure
24b,eandf).
Figure25showstheevolutionoftheproofstress,0.2,at300Casafunctionofthe
solutiontreatmenttimeat490C.Thesolutiontreatmentcausesadecrease inthe
hightemperaturestrengthoftheinvestigatedalloyswithinthefirst4h.
ThealuminidecontainingalloysexhibithigherstrengthsthantheAlSi12alloydueto
the larger volume fraction of rigid phases, amounting to 1824%, the high
interconnectivityofthealuminidesandtheirhighcontiguitywiththeeutecticSi.The
alloys AlSi12Ni1 and AlSi10Cu5Ni1 contain ~8vol.% of aluminides. However, the
aluminides in theAlSi10Cu5Ni1 alloy present a higher degree of interconnectivity
(~94% in ascast condition and ~75% after stabilization) than the AlSi12Ni1 alloy
(~60% in ascast condition and ~50% after stabilization). Xray diffraction analysis
revealed that the addition of Cu produces various aluminides increasing the
contiguity: Al7Cu4Ni, Al2Cu, Al4Cu2Mg8Si7 and AlSiFeNiCu. ~90% of all the
aluminides and all the eutectic Si are forming a highly interconnected rigid 3D
structure inAlSi10Cu5Ni1which increasesthehightemperaturestrengthby~100%
withrespecttotheCufreealloyAlSi12Ni(Figure25).
ThepistonalloysAlSi10Cu5Ni1andAlSi10Cu5Ni2showsimilarstrengthintheascast
condition.AlSi10Cu5Ni2containsmorealuminides(~13vol.%)and itretainsa~15%
higherstrength levelthanAlSi10Cu5Ni1afterthesolutiontreatment.Furthermore,
the3Dnetworkoftherigidphasesispracticallyfullpreserved(~97%)duringsolution
treatment of the AlSi10Cu5Ni2 (Figure 24d, f), owing to the larger degree of
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contiguitybetweenthealuminidesandeutecticSi.Thisresultsinanextraincreaseof
loadtransferfromtheAlmatrixtothereinforcing3DnetworkofaluminidesandSi
whichismoreimportantathightemperatureswherethematrixbecomesrelatively
softer.
The results indicate that the design of cast AlSi alloys for high temperature
applications requires a deep understanding of their 3D architecture and the
mechanisms governing its evolution with temperature and time. Synchrotron
microtomography is a powerful tool to achieve these tasksmainly due its non
destructivenature,suitablesamplesizetoresolutionratioandthepossibilitytouse
phasecontrasttorevealtheeutecticSiembeddedintheAlmatrix.
Figure24.3DstructuresofaluminidesandSiafter4hofsolutiontreatment:a)SiinAlSi12,b)Siand
aluminidesinAlSi12Ni,c)aluminidesinAlSi10Cu5Ni1,d)aluminidesinAlSi12Cu5Ni2,e)Siin
AlSi10Cu5Ni1andf)SiinAlSi10Cu5Ni2.
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Figure25.Proofstress0.2at300Cfortheinvestigatedalloys
asafunctionofthesolutiontreatmenttime.
4.2.3. Submicrometerholotomographyofmultiphasemetals
Themicrostructural characterization ofmultiphasematerials by conventional 2D
metallographycanbeinsufficientif,forinstance,connectivitybetweenphasesexists,
or the orientation of constituents varies throughout the volume. For this, 3D
characterisationtoolsareneeded.Synchrotronmicrotomographyhasshowntobea
powerful technique to reveal the architecture of materials. Furthermore, the
coherence of the beam can be exploited applying quantitative phase contrast
tomographyorholotomography[82]toimagecomponentswithsimilarattenuation.
Thespatialresolutionachievablebyparallelbeamsynchrotronmicrotomography is
about1m.Thiscanbeimprovedusingmagnifyingoptics[83].Thishassofarbeen
achieved for samples with diameters
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sizesof60nmand51nmwereusedfortheAlalloyandTialloys,respectively.Phase
retrieval forholotomographywasachieved from recordings at four focalpointto
sampledistances.
Examplesofthreelightalloysarepresented.Theirmicrostructuresareshowninthe
scanningelectronmicrographs(SEM)atthetopofFigure26:
AlMg7Si4alloy:themicrostructureexhibitsafineternaryeutecticformedbyAl,Si
andMg2Siwithlamellarstructures>150nm.Ferichintermetallics(IM)appearwithin
theprimaryAl.
Ti10V2Fe3Alalloy (Ti1023): thealloycontains~30%ofhcpphasedistributed
withinbccgrainsnotobservablebyabsorptioncontrast.
Ti6Al4V (Ti64) alloy reinforcedwith 5vol% TiB needles (Ti64/TiB/5w): the Ti64
alloymatrixconsistsofgrainsseparatedbynarrowzonesandTiBneedles.
Holotomography is well adapted to these materials as there is low absorption
contrastbetweenthepresentphases.
Portions of the reconstructed holotomography slices are shown at the bottom of
Figure26.Thegreylevelscaleslinearlywiththeelectrondensityoftheconstituents
revealing all the phases observed in the SEMmicrographs. Volume views of the
minorityphasesareshowninFigure27.
AlMg7Si4:theternaryeutecticwith interconnectedSiMg2Sistructuresasthinas
~180nm (green)are identified.The IMparticlesandAlaremade transparent in
Figure27a).
Ti1023:grains>200nmareidentified.InFigure27b),aninterconnectedstructure
ofparticlesremainedfromanincompletebreakupofthelamellarstructureduring
preforging(blue),whilesecondarygrains(green)areembeddedinthephase.
Ti64/TiB/5w:theandphasesintheTi64matrixareidentifieddownto200nm.
In Figure 27c), TiB needles (green) are connected to irregularly shaped grains
(othercolours),forminganinterpenetratingstructurewithinthephase.
MagnifiedsynchrotronholotomographyusingKBopticswasusedtocharacterizethe
3Darchitecture of Al and Tialloy samples of ~0.4mm diameterwith energies of
17.5 and 29keV, respectively.Using the nanofocusing KBsystem for such a high
energy (29keV) is reported for the first time. This experimental setup combining
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synchrotron radiation, KB optics and holotomography opens a new level of
resolution (180nm) for nondestructive 3D imaging of representative samples of
multiphasemetals.
Althoughmagnified synchrotron holotomography is not planned in the proposed
beamline,theholotomographymethodologycanbeusedtocharacterizemultiphase
materialsaslongasthesizeofthephaseareabovetheresolutionofthetechnique.
However,themagnifyingopticssetupcouldbe included inafurtherupdateofthe
beamline.
Figure26.Top:scanningelectronmicrographsoftheinvestigatedmaterialsBottom:portionsofslices
ofholotomographyreconstructionsoftheinvestigatedmaterials.Fromlefttoright:AlMg7Si4alloy,
Ti1023alloyandTi64/TiB/5w.
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Figure27.Renderedvolumesoftheinvestigatedmaterials:a)interconnectedSiMg2Sistructure
(green)inAlMg7Si4;b)largerparticlesremainingfrompreforging(blue)andindividualsecondary
grains(semitransparentgreen)inTi1023;c)TiBneedles(green)andirregularlyshapedgrainsin
Ti64/TiB/5w(othercolours).
4.3. Lifesciencesandbiomedicine
In contemporary biomedical, aswell as clinical research, structural imaging has a
central role. Current approaches are focused in a multiscale methodology.
SynchrotronXraybased imagingprovide thepossibility to integrateseveralof the
required length scale, providing highresolution (submicrometre) detail in large
samples (tens of centimetres) [85]. SXCT with phasecontrast offers exciting
possibilitiestosupportSystemsMedicineresearch.Substructuresoforgans,oreven
whole (small) organisms, can be investigated, segmented and quantified from a
single3Ddataset.Thisalsoenablestoobtainthestructuraldatathatisrequiredfor
e.g.performingcomputationalmodellingoffunctionalorgan[86],suchasitisdone
inthecontextoftheVirtualPhysiologicalHuman[87].
PotentialapplicationsforahardXraytomographybeamlineatALBA:
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4.3.1. HighresolutionStructuralImagingofstatictissue:
Multiresolution imaging at the (sub)micrometre scale is essential in evaluating
structuralpropertiesandinducedchangesinalotofbiomedicaldomains.Theability
toimagelargevolumesoftissueatthisscaleoffersnovelinsightstowardsassessing
pathological remodeling aswell as towards providing data for e.g. computational
modeling.ExamplesofthisareprovidedinFigure28,Figure29,Figure30.
Elastine bres in the aortic wall
Fibre orientationchange
Falsetendon
Intramuralvessel
Coronory arteryostium
Aorticvalve
Tricuspidvalve
LV wall
Long.
Circ.
Long.
Figure28.Phasecontrastimagingofwhole(rodent)hearts.Besidetheanatomicaldetailatorgan
level,thedetailedfibrestructureinwhichmyocytesareorganisedcaneasilybeassessed.Additionally,
vesselscanbeobservedandextractedusingcomputationaltools[89].
Figure29.Imageofapretermrabbitpupthorax,focusingontheair/lungtissueinterface[90].
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Figure 30. Spatial resolution of histology, Xray phase tomography, and MRI microscopy
demonstratingthatresolutiondecreasesfromhistologyviaPCmCTtomMRI[91].
4.3.2. HighthroughputVirtualPathology
Whole organism assessment, as e.g. in
human autopsies or phenotyping of
geneticallymodifiedmodelorganisms,isstill
an essential source of information, both in
basic research as well as in clinical
understanding of diseases. Traditional
autopsieswoulddescribeand,insomecases
image, the whole organism and additional
detailed information would be provided
from destructive (microscopy) investigation
of specific organs or tissue samples.
However, this leads to different (sparse)
information at the different spatial
resolutions and an integration of organ and cellaggregate level is extremely
challenging,verytimeconsumingandexpensive.Thismeansthatwholeorganisms
areonly investigated in rarecases, suchas for specific researchprojectsore.g. in
human fetuseswhen thecauseofperinataldeath isunknown.Othermethods like
MRIareverytimeconsumingandwith limitedresolution,Figure31.SXCT inphase
Figure 31. A false positive MRI post
mortem, suggesting lung changes while
histologywasnormal.
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contrastmode,togetherwithahighthroughputforsamplehandling,couldprovidea
way for fast (
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4.4. Historicalbuilding
4.4.1. Insitutomographyofthefluidmovementinsiderocks:applicationto
historicalbuildingconservation
Waterplaysa fundamental role in rockweatheringprocesses. Itspenetrationand
movementinsiderocksgreatlyinfluencesthenatureandintensityofthedamage.X
rayComputedTomography (XrayCT)beingaNonDestructiveTechnique (NDT), is
very useful in mapping water penetration. A General Electric HiVelocity QX/i
helicoidal scannerwas used for the studies in the following parameters: voltage
140kV;current150mA;exposuretime2s;resolution0.203mmx0.203mm,andslice
width0.625mm. Seriesof80virtualsectionswere imaged inparallelatspecified
time intervals. The obtained imageswere 512 x 512pixels in size. Image length:
50mm.
Xray CT provides good images of the internal structure of the samples: the
sedimentary layeringduetodifferences incompositionandporosity isclearlyseen
aswellasothermineralogical/texturalcharacteristics(Figure33).
Figure33.a)Uniformdistributionofthemineralsexcept in ironoxides layers(atthebottom).b)(1)
voidspaces;(2)finegrainedcarbonates;(3)largegrainedcarbonatesand(4)claysandironminerals.
ThemovementandpenetrationrateofwaterhasbeenmonitoredbyXrayCTduring
freewaterabsorptiontests(UNEEN13755(2002).Figure34a)showsthedifference
betweendryandwetzones intheinteriorofthesamplewhileFigure34b)showsa
3Drenderingofthevolumeillustratinghowthedryopenspacedecreasesduringthe
absorptiontest.
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Thecomparisonof80CTscansperiodicallytakenduringthewaterabsorptiontest
allowstheobservationofthewaterfrontmovementin3D.Thewatermovementis
related to thepetrographic characteristicsof the rock,mainly to the sedimentary
layeringthatcontrolsthedirectionofwaterpenetration.Waterabsorptiondepends
on the rock textureandporosity. Largeporesaregenerallynot connected.Water
penetratesthroughthelayerswithsmallerbutinterconnectedpores.
HounsfieldUnitnumbersprovide aquantitative approach for the identificationof
differentcompositionsandporosities,and thepenetrationrateofwater.MeanCT
values in Hounsfield units (HU), in ROIs (Region Of Interest) are measured at
different intervals of time during the water absorpt