porous materials

~~~~~~~~~~~~Literature Review

strength of usual alloy having Co pools in thestructure was always lower than that of the alloyfree from Co pools; these appeared to act as afracture source .

EFFEcrS OF MolB RATIO ON THE PROPERTIESAND STRUcrURE OF Cr BEARING (FeMo)BORIDE BASEDlIARD ALLOYS

K Tagaki, M Kornai, J. Japan. Soc. Powder andPowder Metallurgy , No.4, June 1989, 390-396. InJapanese.

Mechanical properties and phase formation inFe-5B-5Cr-xMoalloys were studied. The effects ofalloy partitioning, lattice parameters and themorphology of MOzFeBz in the alloys were alsostudied.The (TRS) and hardness of the iron-molybdenumboride hard alloys depend strongly on their Mo/Batomic ratio , the type of ferrous binder and themorphology of the MOzFeBz.The best combinationof TRS and hardness is obtained at a MolB ratio of1.0 where lillie third phase exists other thanMOzFeB1: a martensitic binder and the small grainsize boride phase are also present.

RESIDUALSTRESS AND STRESSDISTRIBUTION IN A WC-NiCOMPOSITE

A D Krantz, et al, Materials Science & Engineering,Vol. AU9, November 1989, 127-134.

Differential thermal stresses in a WC-15%Nicemented carbide have been investigated usingneutron diffraction over the range 20- 700K and inloose WC powder. The results show a wide range ofstrain , and hence stress, to be present in the carbidephase of the composite. The range is from hightensile to high compressive values.

SYNTHESES OF ULTRAFINECERMETPOWDERS BY REACTIVE PLASMA METALREACTION

S Ohno, et ai, J. Japan Inst. Metals, Vol. 53, No.9,1989,936- 945. in Japanese.

Ultrafine powders of Fe-TiN. Ni-TiN and Co-TiNwere prepared by arc melting the binary alloys,Fe-Ti etc , vaporisation and deposition in a HzlNzgas at 0.1 MPa. The alloys were single phase at,40-50%Ti. Above this TiN formed. The mechanismof formation is described.

STRUCTURE AND PROPERTIES OF BORONNITRIDE

T S Bartnitskaya et al, Poroskavaya Metallurgiya,No.6, 1988, 52-56. In Russian.

Boron nitride powder produced by carbothermicreduction, with simultaneous nitriding, has beenstudied by electron microscopy, X-ray diffractionand UV spectroscopy. Behaviour of the powd er inmineral acids and NaOH has been assessed. Themorphology of the powder is studied, fibres havebeen observed as well as grains. The particle size isnot greater than 300 nm with a specific surface of25 mZlg. The stability is comparable with that ofrough dispersed powders.

MPR March 1990

Porous Materials

UPSET FORGING OF POROUS BRASS BILLETS

G A Baglyak, Poroskovaya Metallurgiya, No.7.1988.33-37. In Russian

Influence of initial porosity. specimen dimensionsand strain rate and porosity of forged billets isexamined. Density may be increased or decreased .

PROPERTIES OF POROUS MATERIALS

V. K. Sheleg, et al, Poroskovaya Metallurgiya, No.7,1988.74-8. In Russian.

The structural, capilliary and filtering properties ofsome steels, titanium bronze and other alloys aredescribed.

AUGERSPECTROSCOPYOF FRACTURED PMMATERIALS

B Y Dorofeev, Poroskovaya Metallurgiya, 8. 1988.36-40. In Russian.

Results are presented of Auger electronspectroscopy used to study segregation in fracturedspecimens of hot pressed materials.

Superalloys

OXIDEDISPERSION STRENGTHENED (ODS)Ni-BASESUPERALLOY

Y Kawasaki, et al, J Korean Ins. of Metals, Vol. 27,No.6, 1989, 529-536. In Korean.

Mechanical alloying used to prepare alloy TMO-2using (a) Ni pellets in attritor, extrusion andisothermal annealing and (b) steel balls, extrusion,zone annealing and precipitation hard ening. Alloy(a) gave creep rupture life of 3500h at 1050 and16kgf/mm2 and (b) 7475h under same conditions.M6C observed in some specimens. gives reducedelongation.

CLEANPM SUPERALLOYS

J D Destefani, Adv, Materials & Processes, No.9,September 1989, 63.

A review of process technology in PM with respectto steps taken to ensure freedom from avoidabledefects such as inclusions in raw materials , controlof composition and best particle shape and particlesize distribution.

STABILITY OF OXIDEIN INCONELr.1A6000

G B Schaffer, et al, Acta Metall., Vol. 37, No.9.September 1989, 2551-2558.

Analytical transmission electron microscopy usedto study oxides in mechanical alloyed, dispersionstrengthened Ni-base superalloy. Inconel, Variousternary oxides of Al and Y were observed,

DISPERSOIDS IN 'INCONEL' MAGOOO

G BSchaffer, et al, J. Materials Science. Vol. 24, No.9, September 1989, 3261-3266.

Oxide disp ersoids in a mechanically alloyed,dispersion strengthened nickel based superalloyInconel MA6000* were identified by analyticaltransmission electron microscopy. Four mixed AIYoxides were found including a new YAID)polymorph. The structure of this was determined.All four oxides contained significant amounts of Zrby depl etion of the nickel base matrix .

*Trade mark of INCO.

PRIOR PARTICLEBOUNDARY PRECIPITATION(PPB) IN Ni BASESUPERALLOYS

C Marquey, et al.Int, J. Powder Metallurgy, Vol. 25.No.4, October 1989, 301-308.

P.P.B. precipitation has been observed in alloy713Lc. Rene 95 and Astroloy LC PM alloys by useof energy dispersive spectrocopy and X-raydiffraction. The nature of the precipitates isreported. Practical implications are discussed.

MICROSTRUCTURE OF 'Rene 95' SUPERALLOY

M [ian, et al, PM Technology, Vol. 7, No.4. 1989.213-219. In Chinese.

Samples were heat treated prior to HIP. The effecton microstructure of HIP was studied with theintention of preventing prior particle boundaryprecipitation of carbides, which was achieved bypre HIP heat lreatment.

EUROPEAN PATENTS

331,286PM magnets by compaction of powder in acontainer using fluid pressure provided by a rampress.

General Motors Corp.•March 3. 1988 :Sept. 6. 1989.

331,517High performance magnets made by PM contain Ce,Co, Fe, Cu and one or more of Zr, Ti, Ni, Mn.

Shimetsu ChernInd KK, March4, 1988:Sept. 6. 1989.

331,541Production of powders of improved qualityinvolves passing them through a plasma torchfollowed by cryogenic spray nozzles. to produce anon-equilibrium state.

CommissoEnergie Atomique. Feb. 4.1988: Sept. 6,1989.

331,562Production of fine metal powder by centrifugalatomisation into a liquid gas which may be A or N.

Nuclear Metals lnc., Feb. 29, 1988 : Sept. 6. 1989.

331,679High density sintered parts of high-speed orstainless steel contain 2-8% Cu added to the

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