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} " W E A RE L S E V I E R Wear 216 11998) IhO-17l

S l id i n g w e a r b e h av i ou r o f a l u m i n i u m - b a s e d m e t a l m a tr ix c o m p o s i t e sproduced by a nove l l iqu id route

P.H. Shipw ay * , A.R. K ennedy, A.J . W ilkesD , T r ~ r t m , . n t , q M u l , ' r i , d.~ "E ~ z ~ i m ', 'r in . ~ , r o d M a w r i , d ~ l ), ,. ~ ig n . U / d w , r x i l y n / ' N n t t i n ~ h u m . U n i v e r x i ( v P e r k . N n / t i, .~ h m p ~ N G 7 2 R D , U K

Receivcd 13 I~lay 1997:ac,.'cplcd 30 June I ~,%t7

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TiC-re inh)rce d MMC ,, , have been produced in a range of a lu mi niu m alh~ys using a novel cast ing techn ique wh ich resul ts in spl)ntaneou:~incorp~ra t ion o f the p a r t i c l e s in to the melt and thus strong bonding b e t w e e n the par ti c les and the mat r ix . The s l id ing w ear behav iour o f theex t ruded c o m l x ) s i t e s has been s tud ied as a Iunc t ion o f load and par t i c le vo lum e f rac t ion and has been compared w i th a com me rc ia l l y ava i lab leSiC- reinforc ed coml~).~ite, in all cases, al l t~y reinfo rcem ent res ulted in a reduction in wear r: lte and an increas e in the load at which thet rans i t ion IYom low r -a te wear to h igh ra te wear ,~cur red . In the low rate wear regime, the wear c(~cf l ic ients of a l l the a l loys in both there in fo rced and unre iu fo rced s la tes were s im i la r , and s i n c e the T iC- re in l~rced A3 56 a l loy was the hardes t (due in par t to the g ra in re f in ing~ ' t i o n o f Ti C ) , i t exhib i ted Ihe lowest w ear rate ( low er than that of the SiC -re inforce d campt~si te) . We ar of the steel c,~unter t'ace dependedo n t h e m e c h a n i s m o f w e a r o f t h e c o m i c ) s i t e . A n i n c r e a s e in l o a d g e n e r a l l y resulted i n an increase i n we ar r a t e o f b t J t h t h e co m p o s i t e p in an dc,mntcr face , and the reasons for th is are presented. Increasing the voluune f ract ion of par t ic les in a compo s i te reduces i ts wear ra te bu t genera l l yin~rea. ,~s the wea r rate t ) f the counter face , i t i s sugges ted tha t when ~ ) th counter face and co m l~s i te wear a re cons idered , an opt imu m wdu metractio n of particle., , exists at whic h wear is lowest. 1998 Elsevie r Scie nce S.A. All r ights reserved.

/* , 'w~vrd.~: TiC ; M M ('; Slidm~ wear: ('mnlerl 'ac wear; ( '=ql] l~)~ilc

1 . I n t r o d u c t i o n

D i . ~ o n t i n u o u s l y r e i n f o r c e d a l u m i n i u m m a t r i x c o m p o s i t e s( D R A M C s ) h a v e e m e r g e d f r o m t h e n e e d f o r l ig h t w e i g h t ,h i g h s t i f f n e s s m a t e r i a l s w h i c h a r e d e s i r a b l e i n m a n y a p p l i -c a t i o n s s u c h a s h i g h s p e ed r e c i p r o c a t i n g m a c h i n e r y . R e i n -f o r c e m e n t u s u a l l y c o m p r i s e s p a r t ic l e s o r w h i s k e r s o f ac e r a m i c s u c h as s i l i c o n c a r b i d e o r a l u m i n a a n d s i g n i l i c a n ti n c r e a, ,~ s i n s t i f f n e s s a n d s t r e n g t h c a n b e c o n l ' c r r e d w i t h e v e ns m a l l n ~ i n f o r ce m e n t v o l u m e f r a ct i on s . M a n y o f t h e a p p li c a -l i o n s f o r w h i c h D R A M C s a r e d e s i r a b l e a l s o r e q u i re e n h a n c e dt r i b o l o g i c a l p e r f o r m a n c e . T h e r e e x i s t s a la r g e b i l l y o f l it e r -a l u r c c o n c e r n i n g t h e w e a r P e r f o r m a n c e o f s u c h m a t e r i a l s .m u c h o f i t s h o w i n g t h e c o m p o s i t e s i n a gt x~ cl l i g h t c o m p a r e dto t h e a l l o y s i n th e u n r e i n f o r c e d s t a t e .

T h e w e a r r e s i s t a n c e o f c o m p o s i t e s h a s r e c e i v e u 0 1 r u t ha t t e n t i o n i n t h e l i t e r a tu r e b u t d i r e cl c o m p a r i s o n b e t w e e np a p e r ~ i s o f t e n d i f t i c u l t d u c t o s p e c i l i c d i f f e r e n c e s i n th e w e a rt e s t in g p r (x : e d u re . W o r k c o n c e r n i n g t h e u n l u b r i c a t c d s l i d i n gw e a r b e h a v i t )u r o f s u c h m a t e r i a l s h a s e - , u m i n e d a r u m b e r o f

" ( ' lJn,,plmdin~ au llm r, l;a~,: + 44 i I.~ g51 37 41 : e-m ini:IdUdap.,,htpv,a)- a mA tingh:qlLaC.ukI J 0 4 3 . | ( ~ 4 ~ 1 9 K I $ Jg.IlO i" I~H,J~ ~l,,~c; er .5,..hmce ".;.A. A ll rig ht ,, rc,,qP,d.t 1 1 5 0 0 4 3 . ] b 4 g ( 9 7 ) O O l 5 3 - I

v a r i a b l e s s u c h a s t h e c o n t a c t p r e s s u r e I I - 9 I , s l i d i n g v e l o c i t y1 7 - 1 I I . t e m p e r a t u r e I 1 2 , 1 3 1 . t h e c o u n t e r p a r t t y p e 1 8 , 9 I ,p a r t i c l e v o l u m e f r a c t i o n 1 3 - 5 . 7 . 1 4 , 1 5 i, p a r t ic l e s iz e 1 2 , 1 4 -1 7 I . m a t r i x t y p e 1 1 5 ! a n d h ea t tr e a t m e n t 1 1 6 - 1 0 J . A n u m b e r

o f m e c h : m i s m s h a v e b e e n p ro l ~ ) s e d to e x p l a i n t h e s l i d i n gw e a r b e h a v i o u r o f t h es e c o m p o s it e s , m a n y o f w h i c h a re d is -c u s se d i n a n e x c e l l e n t r e v i e w o f t h e s u b je c t 1 2 0 J . W h i l s tc e r t a in e x p e r i m e n t s s h o w t h e c o n v e rs e , i t i s g e n e r a l l y d e m -o n s tr a te d t h at re i n f o rc e m e n t o f a l u m i n i u m a l l o y s w i t h p a n i c -u l a t e m a t e r ia l s d o e s r e s u l t i n r e d u c e d s l i d i n g w e a r ra t e s a n di n c r e a s e s t h e c r i t i c a l c o n t a c t p r e s s u r e a t w h i c h t r a n s i t i o n sf r o m m i l d t o se v er e w e a r ~ : c u r . H o w e v e r . w h i l s t t he w e a rr a te o f t h e C O m l ~ s i t e i s r e d u c e d , th e w e a r r a te o f t h e c o u n -t e r f~ c e a ~ a i n s t w h i c h t h e c o m [x ~ s i te i s s l i d i n g i s u s u a l l y s i g -n i f i c a n t l y i n c re a s e d : t h u s , th e h e n e l i t o f r e i n f o r c e m e n t o n t h ew e a r r a t e o f t h e w h o l e s y s t e m i s l e s s c l e a r t h a n w h e n t h ec o m p s ) s i t e a l o n e i s c o n s i d e r e d 1 8 , 1 2 . 1 4 . ! 5 . 1 7 . 2 1 . 2 2 I ,

T h e r e i n f o r c e m e n t t y p e is s i g n i l i c a n t i n d e t e r m i n i n g t h eh e h a v i o u r o f t he co u n p t) s it e : w o r k c o m p a r i n g t h e w e a r h c h a v -i o u r o f c o n ) l' K )s it e s w i t h s i l i c o n c a r b i d e o r a l u m i n a r e i n f o r c e -] ] t e n t h a s g e o t e r a l l y p r e f e r r e d t h e f o r m e r , c o n c l u d i n g t h a ic~mlp~)s i tes per l~) rm be t te r due to the h igh er ha rdness [ 151


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P.H. Shipway el aLI Wear 216 (1~gb~) I~J-171 161

a nd g re a t e r r e s i s t a nc e to f r a c tu re I 121 o f s i l i c on c a rb ide c om-p a r e d t o a l u m i n a . S o m e e a r l y w o r k o n c o m p o s i t e s [ l O Ie xa mi ne d the w e a r r e s i s t a nc e fo r I 0 w l.C /~ re in fo rc e me n t w i tha w ide va r i e ty o f pa r t i c l e t ype s a nd c onc lude d tha t r e in fo rc e -me n t w i th S iC , T iC , S i.~N 4 a nd A l_,O ~, a mo ngs t o the r s ,r e s u lt e d i n a n i n c r e a ~ i n w e a r r e s i s ta n c e o v e r t h e u n r i n fo r -t e d a l l o y a n d t h a t r e i n f o r c e m e n t w i t h T i C r e s u l t e d i n s li g h t l yg r e a t e r i m p r o v e m e n t s i n w e a r r e s i s t a n c e t h a n w i t h S i C f o rthe sa me pa r t i c l e s i z e a nd vo lume f ra c t ion . A more de t a i l e ds t u d y o f t h e r o le o f p a n i c l e t y p e i n t h e s l i d i n g w e a r b e h a v i o u ro f D R A M C s h a s b e e n p r e s e n te d b y M a n i s h R o y e l a i. [ I I .T h e y p r o d u c e d c o m p o s i t e s b y a p o w d e r m e t a l l u r g y t e ch n i q u ew i th 2 0 vo l.C /r o f s i l i c on c a rb ide , t i t a n ium c a rb ide , bo ronc a r b i d e a n d t i t a n i u m d i b o r i d e a s t h e r e i n f o r c e m e n t s . T h e ylbun d tha t t i t a n ium c a rb ide w a s the l e as t suc c e ss fu l r e in fo rc e -m e n t . r e d u c i n g t h e v o l u m e t r i c w e a r r a te t o 3 8 ~ o f t h a i o f t h em a t r i x a t 2 . 8 3 M P a c o n t a c t p r e s s u r e ( S i C r e i n f o r c e m e n tr e d u c e d t h e c o m p o s i t e w e a r r a t e t o 2 3 ~ o f t h a t o f t h e m a t ri x )a n d t o 0 . 8 7 % o f t h at o f t h e m a t r i x a t 5 . 6 6 M P a c o n t a c t p r e s-su re ( S iC re in fo r c e m e n t r e duc e d the c omps)s i te w e a r r a t e to0 .8 2 9~ o f t h a t o f t h e m a t r i x ). T h e p o o r e r p e r f o r m a n c e o f T i Cr e i n f o r c e m e n t c o m p a r e d t o S i C r e i n l o r c e m e n t r e su l t ed f r o mg r e a t er s u b s u r f a c e c r a c k i n g w h i c h w a s c a u . ~ d b y d c c o h e s i o na t t h e p a r t i c l e - m a t r i x i n t e r l a c e r e s u l t i n g f r o m t h e h i g h e rs t r e n g t h o f t h e T i C - r e i n f o r c e d s y s t e m . H o w e v e r . i t s h o u l da l so be no te d tha t the T iC pa r t i c l e s i z e w a s a ro und h a l f tha io f t h e S i C p a r t i c l e s a n d a s s u c h d i r e c t c o m p a r i . ~ n o f w e a rra t e s i s d i f f i c u l t . ( A num be r o f w orke r s [ 2 ,14 . ! 5 ] ha ve sug -g e s t e d t h at s m a l l e r r e i n f o r c i n g p a r t ic l e s i z e s l e a d to h i g h e rw e a r r a t e s a n d t h u s t h e d a t a p r e . ~ n t e d b y M a n i s h R o y e t a l.[ 1 I ne e d to be c o ns ide re d in l i gh t o f t h i s . )

T h e m e t h o d o f m a n u f a c t u r e o f c o m p o s i t e s c l e a r l y i n f l u -e n c e s t h e m e c h a n i c a l p r o p e r l i e s o f t h e m a t e r i a l [ 2 3 .2 4 1 a n dthus w i l l ha ve a n e f t~c t on the t r i bo log ic a l pe r fo rma nc e .T h e r e a r e s e v e r a l t e c h n i q u e s a v a i l a b l e f iw m a k i n g p a r t i c le -r e i n f o r c e d m e t a l m a t r i x c o m p o s i t e s r a n g i n g f r o m l ~ ) w d e rm e t a l l u r g y m e t h o d s t o c a s t in g . O n e o f t h e m o s t e c o n o m i c a l l ya t t ra c t iv e i s t h e c a s t r o u t e w h i c h e m p l o y s n e a r s t a n d a r d f o u n -d ry p ra c t i c e . The re a rc . how e ve r+ a nu mb e r o f d i sa dva n ta ge sw h i c h t i m i t t h e p e r l b r m a n c e o f c a s t r o u t e c o m p o s i t e s , t h em o s t i m p o r t a n t b e i n g t h e s e g r e g a t i o n o f r e i n f o r c e m e n t t of o r m i n h o m o g e n e o u s , c l u s t e r e d s p a t i a l d i s t r i b u t i o n s a s are su l t o f a gg lome ra t ion , , ,~d ime n ta t ion o r pa r t i c l e push ingd u r i n g s o l i d i l i c at i o n p r o ce s s i n g 1 2 5 ,2 6 1 . T h e m e c h a n i c a lp rope r t i e s o f t he c omp os i t e a re a f fe c t e d by the I~ )nd be tw e e nthe ma t r ix a nd the pa r t i c l e : pa r t i c l e e ng u l fm e n t du r ing so l id -i l i c a l ion ind ic a t e s t ha t t he so l id m e ta l ha s a n a f f in i ty fo r t hepa r t i c l e a nd thus ge s )d bond ing i s e xpe c te d 127 ] . S t rongb o n d i n g b e t w e e n p a r t ic l e a n d m a t r ix i s d e s i r a b l e f o r w e a rre s i s t a nc e a s w e l l a s o the r m e c ha n ic a l p rope r t i e s 16 ,7 I: C a r -a c os t a s e t a l . [ 281 e xa m ine d a c ompo s i t e w i th T i B 2 re in fo rc e -s e n t w h i c h h a d h e c n f i )r m e d in s i lo a n d c o n c l u d e d t h a t it sde s i r a b le w e a r p rope r t i e s r e su l t e d f rom the s t rong ma t r ix -pa r t i c l e bonds . The s t rong bond me a n t t ha t pa r t i c l e l o ssoc c u r re d by a l t r i l i ve f r a c tu re r a the r t ha n de c ohe s ion . Ther e m a i n i n g p a r t o f a n y p a n i c l e c o u l d s t il l c o n f e r w e a r r e s ts -

l a n c e t o t h e c o m p o s i t e b y b e a r i n g t h e l o a d a n d d e b r i s w a ss m a l l e r t h a n t h a t p r o d u c e d i f d e c o h e s i o n o c c u r r e d : t h u s t h e. ~ v e r i t y o f a b r a s i v e w e a r o f t h e c o m p o s i t e b y t h e d e b r i s w a sre duc e d .

T h i s w o r k w i l l e x a m i n e t h e s l i d i n g w e a r b e h a v i o u r o f ar a n g e o f a l u m i n i u m a l l o y s m a d e b y a m o d i f i e d l i q u i d m e t a l -lu rgy t e c hn iqu e 129 .301 w h ic h re su l t s i n a l loys w i th f a vou r -a b le me c ha n ic a l p rope r t i e s e spe c ia l ly s t i f fne ss . Thed i s p e r s i o n o f pa r l i c t e s t h r o u g h o u t t b e m a t r i x i s a c h i e v e d n o tby v igou rous s t i r r i ng o f t h e pa r t i c l e s i n to a m e l t o r pa r l i a l ly~ ,~ lid if i cd me l t . bu t by s pon la nc ou s inc o rpo ra t ion a s a r e su l to f p rom ot ing w e t t ing o f t he p ' ,u 'U c le s by the l i qu id a l loy . Them e t h o d a n d t h e c h o i c e o f p a r t i c l e - m a t r i x c o m b i n a t i o n e n s u r eu n i f o r m d i s t r i b u t i o n o f t h e r e i n f o r c e m e n t w i t h i n t h e a l l o y a n dg o o d i n t e rr a c ia l b o n d s b e t w e e n t h e r e i n f o r c e m e n t a n d t h em e t a l . T h e h o m o g e n e o u s p a r t i c l e d i s t r i b u t io n a n d g o o d i n te r -f a c i a l bond ing re su l t f rom a low pa r t i c l e - so l id in l e r fa c i a le n e r g y a n d t h u s n o t a l l p a r t i cl e t y p e s c a n b e i n e o r p o f a l c d in t ome l t s by th i s rou te : K e nne dy e t a l . [ 29 ] r ep ro1 tha t l" iC , T iB 2a n d B ,~ C h a v e b e e n s u c c e s s f u l l y i n c o c [ ~ a t e d ,

2. Experimental procedure2,/. Materials

M e t a l m a t r ix c o m p ( ~ i l e s w e r e m a d e b y t h e i n c o rp o r a t io no f T i C p a r t i c le s i n t o t h re e a l u m i n i u m a l l o y t y p e s b y a p r o c e s sp r e v i o u s l y d e . ~ r i b e d b y K e n n e d y e [ a l . 1 2 9 l . P a r l i c l c s o f T i Cw i t h a n a v e r a g e p a r t i c l e s iz e o f l 0 i x m w e r e o b l a i n e d f r o mt h e L o n d o n a n d S c a n d i n a v i a n M e t a l l u r g i c a l C o . L t d . T h r e ea l loy typc .~ w e re c ho se n to de mons t ra t e t he w ide a pp l i c a b i l i t yo f t h e a d d i ti o n m e t h o d a n d t h e b e n e f i ts a s . ~ i a l c d w i t h i t,n a m e l y a c o m m e r c i a l p u r it y a l u m i n i u m ( C P ) . a w r o u g h t t y pea l loy . A I -- .4 w t .e ~C u ( A I -4C u ) a nd a c a s t ing type a l loy , A I ---7 w t.C ~ S t -0 .3 w t .e ~ Mg (A 35 6) . C oJnpos i t e s w e re ma d e w i thl 0 v o l . ~ T i C p a r t i c l e s a n d i n t h e c a . ~ o f t h e C P a l l o y w i th2 0 v o l . ~ T i C . T h ro u g h o u ! t h e t ex t. a l l e v i a t i o n s o f t h e fo l -l o w i n g t y p e w i l l b e u ~ d ; A 3 5 6 -- I O T iC r e p r e. ~ n t s A 3 5 6 a l l o yc on l a in in~ 10 vol .C ~ TiC .

A s - c a s t m a t e r i a l w a s m ' ~ b y p o u r in g c o m p o s i t e m e l t si n to a c y l in d r i c a l c a s t i r o n m o u l d , ~ m m i n d i a m e t e r a n dI 0 0 m m l o ng . T h e . ~ b i l l et s w e re e x t r u d e d i n t o r o d s a t400 C w i th a n e x t ru s ion ra t io o f 13: I t h rough s he a r f a c e dd i e s a t a s p e e d o f I m m s ~. T h e h o m o g e n e i t y o f t h e re i n -f i ) rc e m e n t d is t r i b u t io n w a s c h e c k e d i n a ll c a . ~ s b y m e l a l l o -g r a p h i c e x a m i n a t i o n o f h m g i t u d i n a l a n d t r a n s v e r . ~ ~ c t i o n so f t h e e x t r u d e d r o d t a k e n a t a n u m b e r o f p o i n t s a l o n g i l sl e ng th .F o r c o m p a r i s o n , a D u r a l c a n m a t e r i a l c o n l a i n i n g t 5 v o l , %SiC pa r t i c l e s w i th a ve ra g e pa r t i c l e s i z e o f 13 Ixm w a s~ x t r ud e d i n t h e s a m e w a y a s t h e e x p e r i m e n t a l a l l o y s . T h eD u r a l c a n a l l o y t y p e i s c l o ~ t o A 3 5 6 a n d s o i t s d a t a w i l l b ep r e s e n t ed a l o n g s i d e t h e d a t a f o r t h e A 3 5 6 . ~ r i es o f e x p e r i -me n ta l a l l oys a nd i t w i l l I ', c r e fe r re d to a s A 356-1 5SIC .


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T h e d i s t r ib u t i o n o f T i C p a r t ic l e s i s u u c l u s t c r e d a n d n e a rh o m o g e n e o u s f o r a d d i t i o n at I ~ h I 0 v o l .% a n d _20 v o l . % a ss i m w n , f o r e x a m p l e , i n th e C P a l l o y s ( F i g , 2 ) . A l l a l l o y t y p e sd e m o n s t r a t e d s u c h d i s t r ib u t i o n a s c a n b e o b s e r v e d i n t h es u b s u r f a c e w e a r z o n e s i n F i g s . 8 - I 1. E x t r u s io n o f t h e a l l o y sh ~ s n o t r e s u l t e d i n f o r m a t i o n o f r e i n f o r c e m c n ! r i c h b a n d s a si s . ~ [ i m e s o b s e r v e d i n s u c h c o m p o s i t e m a t e r i a l s 1 3 2 ] a n da l l th e a l l o y s w e r e v i r t u a l l y p o r e f r e e i n t h e a s - e x l m d e d s t a t e.T i C i s a k n o w n g r a i n r e f i n e r i n a l u m i n i u m a l l o y s 1 2 9 , 3 0 ] b u tt h e a s - e x t ru d e d m i c r o s t m c t u r c r n ad t h i s d if f ic u l t t o q u a n t i f y .T h e m i c r o s t r u c t u rc s o f t h e A 3 5 6 - t y p a l l o y s s h o w n i n F i g s .7 - 9 a r c o f s p e c i a l I io 1 ; A 3 5 6 a l l o y s a re t r a d i t i o n a l l y c a s t i n ga l l o y s a n d t h u s t h e m i c r o s t r u c t u r c s p r o d u c e d b y e x t r u s i o n a r en o t c o n v e n t i o n a l . F i g . 7 s h o w s t h a t e x t r u s i o n h a s b r o k e n u pt h e l o n g n e e d l e s o f e u t e c ( i c s i l i c o n u s u a l l y o . s s o c i a t c d w i t ht h e i n t e r d e n d ri t ic r e g i o n s t o p r o d u c e d i ~ r e t e v e n l y d i s -p e r s e d p a r t i c le s a n d a s s u c h h a s t h e a p p e a r a n c e o f a p a n i c u -


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l a l e - re in f iw c e d c om pos i t e i t se lf . A 35 6- type a l loys r e in l :m . 'e dwith I ( ) v o l . r / , T i C a n d 1 5 w d . ~ S i C ( F i g s . 8 a n d 9 r e , p e t -l i ve ly ) show a ga in the f ine ly d i spe r se d e u te c t i c s i l i c on ;~ longw i th z hc c oa rm: r r e Jn f i ) r c ing pa r l i c l e s ; t he a dde d pa r t i c l e sa g a i n s h o w a h o m o g e n e o u s d i s t r i b u ti o n w i t h i n t h e m a t e r ia l .L a r g e i n t e r m e t a l l i cs o f t i t a n i u m a l u m i n i d e s a n d s i l i c id c s a r ea l so ob .,~' rved in A 3 56 -1 0 vo l/ ,~ T iC ~ R e . 8b a nd F ig . 8 i t ) .

Reinf i~ rcem ent of the a l loy s resul ts in incre ases in hardn . .'s,,,T a b l e i J a s e x p e c t ed . T h e h a r d n e s s i n c r e m e n t o n a d d i t i o n

of TiC" dc lxn tds I '~lh on the a lh)y type a nd th e par l icUkLtCvo lu me f ra c t ion s inc e ha rdne ss inc re a se s r e su l t l h ) l~ b o l t l th ere inf i~rc ing na ture o f the add.~d par l ic le ., , and a ls , ) the i r e ffec to f g ra in r e l in in g the a llo~ ,. A l thou gh the ba se a l loy o f A 3 56 -15SIC ~x not iden t ica l t o t h e A 3 5 6 a l l o y , i t s h a r d n e s s i n c r em e n ! O u e t o pa t l i c l e a dd i t ion i s l ike ly to he s ;na l | c r t ha n th in~bsc rve d a f l e r T iC a d d i t ,m s inc e S iC dc a. -s no t g ra in r e l ine1291 . The de c re a s in g inc r e me n t o1" ha rdn e ss w i th suc c e s s iveadd i l ion s ~.ffTi C to ~lheC P a l loy oc c u rs s inc e t i l e l i r st a dd i l i on~ff 1" iC has a fa r grea te r c f l 'ec t on gra in size th . 'm fu r ther~ d d i f i o n s .

The ha rdne ss , i nc re me n t , , ~ .~ r , , ' c d w e re in l i ne w i lh thoser e l x m e d i n o th e r w o r k s [ 1 . 3 . 4 . 1 2 . ] 4 ] . a l t h o u g h d i l t e r c n c e s

in o the r f a c to r s suc h a s pa r t i c l e s i z e a nd type a mon gs t o the r sm a k e d i r e c t c o m p a r i s o n s d i f f i c u l t . M a n i s h R o y e l a l . I l ld e m o n s t r a t e d t h at r e i n f o r c e m e n t w i t h T i C g a v e t a r h i g h e ri n c r e a s e s i n h a r d n e s s t h a n s i m i l a r p ro p o r t i o n s o f S i C a sobse rv e d in th i s w ork : i t is p ropose d tha i t h i s is a ga in due tothe g ra in r e l in in g na tu re o f T iC pa r t i c l e s .4 . 2 . C o m p t ~ . v i t e n ' e a r

D a ta on the s t e a dy s t a t e w e a r r a t e s o f t he c ompos i t e p in six p re se n te d in F ig s . 3 -5 . W e a r r a te s o f t he un re in lb rc e d a l loysv a r y c o n s i d e r a b l y , w i t h th e w e a r r a t e s o f C P a l u m i n i u m f a rh i g h e r t h a n t h o s e o f t h e o t h e r tw o a l l o y s . W e a r r a t es o f A I -4C u a re low e r tha n tha t o f A 3 56 a t t he low e r tw o t e s t l oa ds .a s w o u l d b e e x p e c t e d d u e t o t h e a l l o y ' s h i g h e r h a r d n e s s .H o w e v e r , w h e n s l i d i n g u n d e r a n a p p l i e d l o a d o f 7 8 N . t h ew e a r r a t e o f A I - 4 C u i s m o r e t h a n t w i c e t h a t o f t h e A 3 5 6a l l o y ; a l t h o u g h b o t h a l l o y s w e a r b y s e v e r e d e l a m i n a t i o n a tt h i s h i g h e r l o ad ( s e e F i g . 7 d a n d F i g . l i b ) . t h e h ar d s i li c o np h a s e i n t h e A 3 5 6 a l l o y ac t s a s r e i n l b r c e m e n t , th u s r e d u c i n gthe w e a r r a t e . Pa n ic u la t e r e in fo rc e m e n t o f ~ ,he a l loy s r e duc e sthe w e a r r a t e i n a l l e a se s .

Exz ~minat ion L~f the w e a r su r l a c c s o f t he p in s g iv e s in fo r -m a t i o n o n t h e t y p e o f w e a r o c c u r r i n g . R e l a t i v e l y 10 w w e a rra t e s a re a ~soc ia te d w i th smtx~lh o r s l i gh t ly g r tm ve d s u r fa c e s( F ig . 6a a r id F ig . 6b w h e re a s ro ugh .~u rfa ce s a re a ssoc ia t e dw.i lh h igh w ear ra tes (Fig . 64:).4 . 2 . i . W e a r o f A 3 5 6 a l l o y t r o d c t m t p o . v i t e s

The " ,, ,e ar t a l e o f t he A 35 6 a l loy inc re a se s w i th a pp l i e dload ( Fig . 3 ~. Fi g 7 sha w s tha t a t dow loads the w e a r s u r f a c ei s r e l a t i v e ly s m l ~ l h w i t h at f e w d e l a m i n a t i o n c r a c k s v i s i ! , le .F ig . 7b sh~Jw s a c ra c k t ) f t he type se e n in F ig . 7a e x te nd ingbe low the su r f i l c c o f t he ma te r i a l w h ic h i s l i ke ly to l e a d t od e t : l c h m e n t o f a w e a r pa r t i c l e . La rge s t r a in s i n t h e s u b s u r f a c er i m e c a n a l~o I ~ ~,bser~. ,ed . Fig . 7c and Fig . 7d sho w a ver yd i f f e r e n t w e a r m o r p h o l o g y f r o m t h a i o b s e r v e d i n Fi g . 7 a a n dF ig . 7 b a ss t~ ia t e d w i lh a 6~5 t ime s in c re a se in w e a r r a te unde rthe h ighe r ~ l id i .qg loa d : t he su r fa c e m)w show s c oa r se a ndr e g u l a r d e l a m i n a t i o n w i t h t h e t h i c k n e s s oi" t h e . ~ d e l a m i n a -t i a n s a n m n d 4 0 p .m ( F ig . 7 d ) . T h e I x m d b ~ t w e e n t h e d e l a m -inu re d l a ye r aJ~d Ihe hu lk a ppe a r s t o he w e a k ( c on t ra s t F ig . 7dw i t h F i g . 7 h ) a n d t h e d e g r e e o f s u b s u r f a c e d e f o r m a t i o n i sh~w.T h e w e a r c ~ c f t i c i e n t o f A 3 5 6 i n c r e a s e s w i t h a p p l i e d l o ada s t h e n ~ c c h a n i s m c h a n g e s i h ) m i n f r e q u e n t d e l a m i n a t , m w i t ha w e l l a t t a c he d t r a ns l~ r l a ye r t o se ve re de l a mina z ion . The~ ,~ea r c oc f l i c i e n t a t t he tw o low e s t l oa ds i s s imi l a r i nd ic a t ingtha t n t ) l r a ns i l i~m in w e a r he t~a v iou r ha s ~c c u r re d ; se ve redc la m m~ t ion a t 711 N re su l t s i n a s ign i l i c a n t ly h ighe r w e a rc o e f f i c i e n t w hi l s t a t t he h~ghe st s l i d ing loa d o f 94 N the w e a rc oe ( f i c i c n t i s a n o rde r o f ma gn i tude l a rge r a ga in .

R e in (o rc e me , ) l o f t he A 356 a l loy w i lh IO w d . '7c ,T iCtc duc e s the w e a r r a t e w i th r e spe c t t o t he un re in fo rc e d a l loy .T h e w e a r c o e f f i ci e n t s o f A 3 5 6 - 1 0 T i C a r c, h o w e v e r , v e r ys imi lm- o those f iw t tl e un re in fo rc e d a l loy e xc e p ! w he n s l id ing


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F i g . 6 . O v e r v i ew , ' m i c r , ) g r u p h s o f co m l ' ~ ) s i t e w e a r p i n s t b l l o w i n g . ~ ti d in g w e a r , ( a ) A 3 5 6 - - 1 5 S I C . 3 1 N I ( m d : ( h ) ( ' P - 2 O T i C . 7 8 N l o a d : 4 c ) A 3 5 6 - - 1 5 S I C '( Du ra lca n 1 . t t4 N load .

u n d e r a l o a d o f 9 4 N . A l t h o u g h t h e r e i s a s ig n i f i c a n t i n c r e a s ei n w e a r c o e f f i c i e n t f i )r A 3 5 6 - 1 0 T i C w h e n t h e s l id i n g l o a d i si n c r e a s e d f r o m 7 8 N to 9 4 N , t h e i n c r e a s e i s n o t a s l a r g e a sf o r t h e u n r e i n f o r c e d a l l o y i n d i c a t i n g t h a t th e r e i n f o r c e m e n th a s r e s t r i c t e d t h e severi ty o f t h e t r a n si t i o n i n t h e w e a r m e c h -a n i s m . T h e s i m i l a r i ty o f t h e w e a r c o e f f i c i e n t s l o r th e t w om a l c r i a l~ i n d i c a t e t h a t a t t h e l o w e r l o a d s , t h e d e c r e a s e i n w e a rr a t e o f the a l l o y c a n b e d i r e c t l y attr ibuted Io lhc incrca . , , edh a rd n e ,+ s o f t h e r e i n f o rc e d a l l o y s i n c e m ) c h a n g e i n m e c h a -n i s m h a s o c c u r r e d . S l i d i n g o f A 3 5 6 - - I O T i C u n d e r a 2 0 N l o a dr e s t d ls i n a s m o o t h s u r f a c e m ( ) r p h o l o g y ( F i g . 8 a ) : n u m e r o u sm i c r o c r a c k s a r e v i s i b l e o n t h e s u r f a c e i n d i c a t i n g t h a t it i s ac o m p a c t e d t r a n s f e r la y e r. T h e s u b s u r f ac e w e a r z o n e s h o w s ath in layer where mater ia l is broken up in to s tr ingers : n od e l a m i n a t i o n ( a s w a s o b s e r v e d i n t h e c a s e o l t h c u n r c i n f i )r c c da l l o y ) i s o b s e r v e d . S l i d i n g u n d e r t h e 7 8 N l o a d r e s u l t s i n as u r f a c e t h a i e x h i b i t s r e g u l a r d e l a m i n a t i o n : t h e t ra u s fi z r l a y e r( F i g . 8 d ) i~ t h i ck ( c . f . F i g. 7 d ) a n d c t m s i s t s o f m e c h a n i c a l l yd e f o r m e d a l l o y a n d f r a c t u r e d p a r t i c l e s o f b o th t h e h a r d S ip h a s e a n d T iC . T h e b o n d b e t w e e n t h e translL-r l a y e r a n d t h es u b s t r a t e is n o t a l w a y s g o o d ( n o t e t h e l a c k o f b o n d i n g i nF i g . 8 d ) w h i c h w i l l re .,, ul t i n l a y e r b r e a k d o w n a n d p n ) d u c t i o no f w e a r p a r t ic l e s . T h e s u r f a c e o f I h e t r a n s f e r l a y e r His()exhib-i ts s a w - t ( u ) t h m a r k s , i n d i c a t i n g t h a t g r o s s m a t e r i a l r e m o , , ' a l i so c c u r r i n g f r o m t h e t r a n s f e r l a y e r i t s el f . T h i s t r a n s f e r l a y e r( a s s o c i a t e d w i t h h i g h w e a r r a te .'. ;) i s th i c k a n d u n . ,a a b l e t o

e i the r tota l de l~md ing o r de lam ina t ion w i th in the laye r andi s in c o n t r a s t t o t he t h i n . h i g h l y c o m p a c t e d t r a n s f e r l a y e r s. ~ c n w h e n s l i d i n g o c c u r s u n d e r t h e l o w e r l o a d s ( F i g , 8 b ) . A tt h e h i g h e r l o a d s , l a r g e r w e a r p a r t i c l e s a r e f o r m e d a n d t h u st h e t r a n s f e r l a y e r b u il d s u p q u i c k l y w h e r e a ~ u n d e r t h e l o w e rl o a d s t h e t r a n s f e r l a y e r i s m a d e u p o f v e r y s m a l l p a n i c l e s a n dis thus h a r d a n d s t a b l e .Rcinf i )rcemcnt o f th e A 3 5 6 - t y p e a l l o y w i t h 1 5 v o l . % S i C( D u r u l c a n I r es u l t s i n a s i m i l a r s u r f a c e a n d s u b s u r f a c e d e f o r -m a t i o n z o n e ( F i g . O a a n d F i g . 9 b ) a s o b s e r v e d w i t h T i Cr e m f i ) r c c m e n t w h e n s l i d i n g u n d e r t h e 3 ! N l o a d . T h e s u r f a c ei s a g a i n g e n e r a l l y s m ( x ) t h ( F i g . g a l . w i t h a t h in t r a n s f e r l a y e r( F i g . O h ) . a l l h o u g h i n s o m e r e g i o n s l h e t r a n s f e r la y e r h a sh e e n r e m o v e d b y f r a ct u r e. S li d in g o f A 3 5 6 - t 5 S i C u n d e r a( )4 N h ) a d r e s u l t s i n g r o s s d e l a m i n a t i o n w i t h i n I h e a l l o y( F i g . 9 c ) a n d n o t r a n s f e r l a y e r f o r m a t i o n ( F i g . 9 ( 1 ) . T h e w e a rr a t e u n d e r t h i s l o a d i s g r e a t e r t h a n i n t h e u n r e i n f o r c e d a l l o ya s t h e S i C p a r t i c l e s a c t as d i s c o n t i n u i t i e s i n l h c Sll ' l lc lure.a i d i n g m a t e r i a l d e t a c h m e n t , a n d the wear p a r t i c l e . ~ c o n l a i n i n gS i C w i l l b c m o r e : | b r a s i v e t h a n t h e d e b r i s l Y o m t i m u n r e i n -f o r c e d a l l o y . T h e w e a r c o e f f i c i e n t s f o r A 3 5 6 - - 1 5 S I C a r e . ~im -i l a r t o th o s e f i )r A 3 5 6 a n d A 3 5 6 - 1 0 T i C f o r th e t w o l o w e rl o a d s. H o w e v e r . t h e s a m e l o w w e a r co e f f i c ie n t i s o b . ~ r v e dw h e n ~ d i di ng u n d e r a 7 8 N l o a d f o r t h e S i C - r e i n f i w c c d a l l o yw h e r e a s i t i n c r e a s e s s i g n i t i c a n t l y f o r t h e u n r e i n f i ) r c e d a n d


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16 6 P,H. Ship~.ay el oL / Wear 216 (1998~ 160-171. . . . ; : : . . . . . . .. . : : : : , . . . . . . . .. . . : . . . . . . .. .

Fig. 7. W ear damage 08"A356 following sliding wear. {a) Surface, 31N Io,'Kl: b ) subsurface~lion, 31 N load: (c) surface. 78 N load: (d) subsurface ~ction.78N load.T i C - r e i n f o r c e d a l l o y s . W i t h S i C r e i n f o r c e m e n t , t h e t ra n s i ti o nt o ~ v c r c w e a r h a s o c c u r r e d w h e n s l i d i n g u n d e r a 9 4 N l o a d .

A t t h e l o w l o a d s , t h e w e a r c o e f fi c i e n t s o f th e A 3 5 6 - , A 3 5 6 - -1 0 T I C - a n d A 3 5 6 - 1 5 S i C - r e i n f o r c e d a l l o y s a r e si m i l a r; h o w -e v e r . t h e T i C - r e i n f o r c e d a l l o y i s h a r d e r t h a n t h e o t h e r s a n dt h u s e x h i b it s t h e lo w e s t w e a r r a te . 1 5 v o l . ~ S i C d e l a y s t h et r ans i t i on t o . seve re we ar t o h i ghe r l oads t han t he I 0 vo l .%T i C r e i n f o r c e m e n t , b u t a t e v e n h i g h e r l o a d s w h e r e t h e S i C -r e i n f o r c t , ' d a l l oy i s a l so wear i ng by a s eve r e de l ami na t i onm e c h a n i s m , t h e T i C - r e i n f o r c e d a l l o y a g a i n e x h i b i t s th e l o w -es t wear r a t e r s . I t mus t a l so b no t ed t ha t t he r e i s 15 vo l ,~S i C in th e c o m p o s i t e a s o p p o ~ d t o i 0 v o l . % T iC ( A 3 5 6 -15T I C cou l d no~ be ex t r uded due t o p r es s l i mi t a t i ons ) andh i g h e r v o l u m e f r a c t i o n s o f r e i n f o r c e m e n t d o r e s u l t i n m o r ef a v o u r a b l e p r o p e r l i e s ( ~ e S e c t i o n 4 . 2 . 2 ). T h u s , t h e p o s i ti v ep e r f o r m a n c e o f t he T i C - r e i n f o r c e d a l l o y i s e v e n m o r es i gn i f i can t .4 . 2 .2 . W e a r o f C P a ll o y a n d ( ' o m p o s i l es

F i g . 4 s h o w s t h a t th e C P a l l o y m a t e r i a l w e a r s r a p i d l y u n d e ra l l t h e l o a d s e x a m i n e d , w i t h w e a r r a t e s i n c r e a s i n g w i t hi n c r e a s i n g a p p l i e d l o a d . T h e w e a r c o e f f i c i e n ts o f t h e a l l o y a ta l l Io ' ,a l s a r c s i gn i l i can t l y h i gh e r t han t hose o bse r v ed wi t h t heA356 a l l oy a t t he s ame l oads . Addi t i on o f 10 vo l .C ~ T i C t ot h e C P a l l o y s r e s u l t ed i n l o w e r w e a r ra t e s , t h e ~ b e i n gb e t w e e n a r o u n d l i v e ti m e s t o s i x te e n t i m e s l e s s t h a n t h o se o f

t h e u n r e i n f o r c e d a l l o y . T h e w e a r c o e f f i c i e n t o f C P - I O T i Cs l id i n g u n d e r t h e l o w e s t l o a d w a s i n th e s a m e r e g i o n a s t h o ~o f t h e A 3 5 6 a l l o y s i n b o t h t h e i r r e i n f o r c e d o r u n r e i n f o r c e ds t a t e s . T h e r e i n f o r c e m e n t w a s n o t a b l e t o p r e v e n t t h e l a r g ei n c r e a s e i n w e a r c o e ff i c i en t o f C P - I O T i C a s t h e lo a d s w e r ei n c r e a se d , E x a m i n a t i o n o f t h e w e a r s u r f a c e a n d s u b s u r f a c ed e f o r m a t i o n z o n e s a f t e r s l i d in g u n d e r 7 8 N ( F i g . 1 0 a a n dF i g . I 0 b ) s h o w s t h a t s u r f a c e d e l a m i n a t i o n h a s o c c u r r e d a l o n gw i t h f o r m a t i o n o f a t r a n s f e r la y e r w h i c h c o n t a i n s b r o k e n T i Cpar t i c l e s . C r ac k i ng ( F i g . 10b) i nd i ca t e s t ha t t h i s l aye r is re l -a t i ve l y b r i t t le : t he c r ack has pene t r a t e d t he t r ans f e r laye r andb e e n s t o p p e d b y t h e d u c ti l e b o d y o f t h e c o m p o s i t e .

I n c r e a s i n g t h e v o l u m e f r a c t io n o f T i C r e i n f o r c e m e n t i n t h eC P a l l o y t o 2 0 v o l . % h a s r e d u c e d t h e m a t e r ia l w e a r r a te a g a i na n d h a s e n s u r e d t h a t t h e w e a r c o e f f i c i e n t h a s r e m a i n e d l o wu n d e r a l l s li d i n g l o a d s e x a m i n e d , a n d o f c o m p a r a b l e v a l u e tot ha t obs e r ved i n o t he r l ow we ar r a t e s i t ua t i ons . F i g . 10c andF i g . loc i sho w t ha t the r e i s no seve r e su r f a ce de l ami na t i onand t ha t a packed , bu t t h i n , t r ans f e r l aye r has f o r med . T hus ,i n c r e a s i n g t h e v o l u m e f r a c ti o n o f r e i n f o r c e m e n t h a s d e l a y e dt h e t r a n si t io n f r o m l o w w e a r c o e f f i c ie n t s t o h i g h w e a r c o e f -f i c i en t s t o h i ghe r app l i ed l oads . T he i nc r ease i n ha r dness o ft h e a l l o y a s t h e v o l u m e t r a c t i o n o f r e i n f o r c e m e n t i n c r e a ~ sa l s o h a s t h e e f f e c t o f d e c r e a s i n g t h e w e a r r a t e e v e n w h e n t h ewear coe f f i c i en t s a r e s i mi l a r .


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PH, Shilm'ay el al. / Wear216 ~1998) 160-171 167

Fig. 8. Wear damage of A356--I0TiC follow ing sliding wear. ( a ) Surface. 31 N load; ~ ~ subsurface ~ection,3 t N load; (c) mffac,78 N load: f d) .qdzmffac.~ciion, 78 N load .4.2.3. Wear af AI--4Cu alloy an d composite.~

T h e u n r e i n f o r c e d A i - -4 C u a l l o y i s a m u c h h a r d e r a l l o y t h a nt h e C P m a t e r i a l a n d b e h a v e s i n a s i m i l a r m a n n e r t o A 3 5 6 .T h e w e a r r a t e s a n d c o e f f i c i e n t s u n d e r t h e 31 N a n d 6 2 Ns l i d i n g l o a d s a r e l o w a n d c o m p a r a b l e t o t h o ~ o b s e r v e d i no t h e r l o w w e a r r a t e s i t u a ti o n s . H o w e v e r , a s i n t h e A 3 5 6 a l l o y .t h e r e i s a t r a n s i t io n i n w e a r b e h a v i o u r a s th e l o a d i s i n c r e a s e df r o m 6 2 N t o 7 8 N . T h e w e a r s u r f a c e f o l l o w i n g s l i d i n g u n d e rt h e 3 1 N l o a d ( F i g . I l a ) i s r e l a t i v e l y s m ~ m th i n d i c a t i n g at h i n , s t a b l e t r a n s f e r l a y e r . F i g . I I b s h o w s t h a t t h i c k , u n s t a b l et r a n s f e r l a y e r s f o r m a t t h e h i g h e r l o a d s , a n d i s s i m i l a r t o t h eb e h a v i o u r s h o w n i n F i g. 7 d . R e i n f o r c e m e n t o f t h e a l l o y w i t hI O v o l . % T i C r e s u l t s i n a d e c re a ~s e i n t h e w e a r r a t e s a n d , ;l i gh td e c r e a . ~ s i n th e w e a r c o e f f i c i e n t w h e n s l i d i n g u n d e r l o a d s o f3 1 N a n d 6 2 N . H o w e v e r , a s i n t h e c o m p a r a b l e A 3 5 6 c o m -p o s i t e , t h e r e i n f o r c e m e n t h a s a g a i n b e e n u n a b l e t o p r e v e n tt h e t r a n s i ti o n i n w e a r m e c h a n i s m o n i n c r c a . ~ o f t h e a p p l i e dl o a d fr o m 6 2 N t o 7 8 N . T h e w e a r m e c h a n i s m s o f A I - 4 C u -1 0 T I C s l i d i n g u n d e r t h e 7 8 N l o a d a r e g r o s s d e l a m i n a t i o n( F i g . I I c ) a n d ~ v e r e s u r f ac e c r a c k in g w i t h n o b u il d u p o f at r an s fe r l ay e r ( F ig . I I d ) .

s h o w i n g o n l y i n fr e q u e n t o r n o c r a c k in g , i n t h i s r e g i m e , a l l o y se x h i b i t r e m a r k a b l y s i m i l a r w e a r c o e f f i c i e n t s b e t w e e n0 . 7 X 1 0- s a n d 1 . 6 X I 0 - s . A s t h e w e a r m e c h a n i sm c h a n g est o o n e o f r e g u l a r d e l a m i n a t i o n , f o r m a t i o n o f a t h i c k t ra n s f e rl a y e r i s o b s e r v e d : t h i s t r a n s f e r l a y e r i s g e n e r a l l y u n s t a b l e a n dw e a r s b y d e l a m i n a t i o n , e i t h e r w i t h i n i t s e l f ( a s e v i d e n c e d b ys a w - t o o th m a r k i n g o n t h e s u r f a c e ) o r d e l a m i n a t i o n a t t h ei n t e r f a c e b e t w e e n t h e t r a n s f e r l a y e r a n d t h e b u l k m a t e r i a l. A st h e a p p l i e d l oad i n c r e a . ~ s , th e w e a r r a t e i n c r e a s e s a s d o e s th ew e a r c o e f f i c i e n t , a n d w e a r n o w o c c u r s b y d e l a m i n a t i e m w i t h -o u t t h e f o r m a t i o n o f a t r a n s f e r l a y e r a t a l l : th i s r e g i m e i sa s s o c i a t e d w i t h v e r y h i g h w e a r c o e f f i c ie n t s .

P a r t i cl e r e i n f o r c e m e n t o f t h e a l l o y s i s g e n e r a l l y . se en t or a i . ~ t h e lo a d a t w h i c h t h e t r a n s i t i o n s in w e a r m e c h a n i s mo c c u r a n d t h e w e a r c o e f f i c i e n t b e g i n s t o r i ~ . i n g e n e r a l ,r e i n f o r c e m e n t o f t h e a l l o y s d i d n o t s i g n i f i c a n t l y r e d u c e t h ew e a r c t m f f i c ie n t s o f t h e m a t e r i a l s h u t t h e w e a r r a t e s w e r er e d u c e d s i n c e r e i n f o r c e m e n t i n c r e a m d t h e h a r d n e s s o f t h ea l l o y s .4.3. Counle.rface wear

4.2.4. Comparison s between tile alloy s3wwmsT h e w e a r b e h a v i o u r o f th e a l l o y s m a y b e c h a r a c t e r i s e d b y

a r e g i m e o f l o w w e a r r a te , w h i c h i s g e n e r a l l y f a v o u r e d b yt b r m a t i o n o f a t h i n t r a n s f e r l a y e r a n d u s m t a ) th s l i d i n g s u r l a c e

F u l l c o n s i d e r a t i o n o f a s l i d i n g I r i b o h ) # c a l s y s t e m r e q u ir e san ana l ys i s o f t he we ar o f t be coun t c f f ace us we l l t ha t o f t hete s t m a t e r i a l. T h e u n r e i n f o r c c d a ! u m i n i u m a l l o y s e x h i b i t t w od i s t i n c t t y p e s o f b e h a v i o u r w i t h r e s p e c t t o t h e i r e f f e c t o n t h e


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10/12

P.H. Shilm'ay er aL ! Wea r 216 ( 1991q~ 160-1 71 169

Fig. I0. W ear damage of CP ha.~edcomposites following sliding wear under a 78 N load. ( a ! CP - t 0' t iC. surface: ( , :. CP-10TKL .~m ~a ce ruction: (c i CP -20TIC, surface; (d) C P-2OTiC,suhsurfa~.e ~ctitm.t h e i n c r e a s e d r e i n f o r c e m e n t c o n t e n t o f t h e a l l o y is d e t r i m e n t a lt o t h e o v e ra l l w e a r h e h a v i o u r o f t h e c o u p l e . H o w e v e r , w h e ns l i d i n g u n d e r a t o a d o f 7 8 N , t h e i n c r e a s e i n r e i n f o r c e m e n tc o n t e n t f r o m 1 0 v o l . % t o 2 0 v o l . % r e s u l t s i n a d e c r e a s e i nb o t h c o m p o s i t e a n d c o u n t e d ' a c e w e ar .

T h e c o m p o s i t e p i n i s p r o t e c t e d b y t h e i n c r e a s e d f r a c t i o no f r e i n f o r c e m e n t p a r t i c le s it s t h e y b e a r m o r e l o a d a n d a r e a b l et o s t a b i l i s e t h e t r a n s f e r l a y e r . H o w e v e r . t h e c o u n t e r f a c e c o r, -t i n u e s t o w e a r b y a m i x t u r e o f a b r a s i v e w e a r a n d s l i d i n g w e a r .i n a t r u e a b r a s i v e w e a r s c e n a r i o , th e n u m b e r o f p a r t i c l e sw i t h i n t h e c o n t a c t z o n e a t a n y t i m e s h o u l d n o t a f f e c t th e w e a rr a te s i n c e a l a r g e r n u m b e r o f p a r t i c l e s r e s u l ts i n a l o w e r l o a do n e a c h p a r t i c le a n d t h u s t h e o v e r a l l w e a r r a t e s ta y s a p p r o x -i m a t e l y t h e s a m e ( o p p o r t u n i t y v s . s e v e r i t y t y p e a r g u m e n t1 3 3 1 ) . T h u s , a c c o r d i n g t o t h e a r g u m e n t p r e s e n t e d i n S e c -t i o n 4 . 3 . I, t h e r e d u c t i o n i n w e a r r a t e o f th e p i n b y i n c r e a s i n gt h e v o l u m e f r a c t i o n o f r e i n f o r c e m e n t s h o u l d l e a d t~ a lo w e rw e a r r a t e o f t h e c o u n t e r f a c e ; t h i s i s c l e a r l y n o t t h e c a s e l k~ rt h e l o w e r l o a d s ( F i g . 4 ) . C o m p o s i t e w e a r r e s u l t s in f r es h( a n d t h e r e f o r e h i g h l y a b r a s i v e ) p a r t ic l e s b e i n g p r e s e n t e d t ot h e c o u n t e r f a c e . C o m p o s i t e w e a r i s s i g n i f ic a n t l y r e d u c e d b yt h e i n c r e a s e i n v o l u m e f r a c t io n o f r e i n f ~w c e m e n t a n d , e v e nt h o u g h t h e v o l u m e f r a c t io n o f p a r t i c le s i n th e c o m p o s i t e i sh i g h e r , t h e n u m b e r o f f r e sh r e i n f o r c e m e n t p a r t ic l e s p r e s e n te dt u t h e c o u n t e r f a c e s t a y s a r o u n d t h e s a m e o r d e c r e a s e s , T h el o a d o n e a c h p a r t i c l e i n t h e c o n t a c t z o n e d e c r e a s e s a s t h e

v o l u m e f r a c t i o n o f p a r t i c l e s i n c r e a . ,e s a m ] t h u s e a c h p ar ~.i cl ew i l t e , m a i n ,~ ha rp a n d h i g h l y a b r a s i v e f o r a l o n g e r p e r i o d a n dt h u s r e s u l t i n a h i g h e r c o u n t e r t 'a c e w e a r r a t e , H o w e v e r , w h e ns l i d i n g u n d e r a n a p p l i e d l o a d o f 7 8 N . th e I 0 v o l . % T i C -r e i n f o r c e d a l l o y e x h i b i t s s u c h a h i g h w e a r r a t e t h a t t h e e f f e c to f t h e n e w p a r t i c l e s p r e m n t e d t o th e c o u n t e r f a c e d o m i n a t e s .r e s u l t in g i n a h i g h c o u n t e r f a c e w e a r r a t e .4 . 3 . 3 . R o l e q [ r e in f i u '~ ' e m e n t p a n i ~ ' l e t y p e hs ~ ' o u m e . r [ a c ewear

F i g . 3 s h o w s t h a t t h e c o u n t e r f a c e w e a r r a te c a u ~ d b y s li d -i n g o f t h e T i C - r e i n f m ' c e d a l l o y i s a n o r d e r o f m a g n i t u d e l a r g e rt h a n t h a t c a u s e d b y s l i d i n g o f t h e S i C - r e i n f o r c e d a l l o y . T h i sb e h a v i o u r i s s u r p r i s i n g g i v e n t h e g r e a t e r a n g u l a r i t y o f t h e S i Cp a r t i cl e s , b u t m a y r e s u lt f r o m t h e l o w f r a c tu r e t o u g h n e s s o fS i C ( 4 . 6 M P a m ~ ) c o m p a r e d t o t h at o f T i C ( 5 . 2 M P a m ~ )1 3 4 ] . I t i s p r o p o s e d t h a t t h e r e l a t i v e l y b r i t tl e S i C f r a c t u r e sa n d t h u s d o e s n ,~ t c a u s e s e v e r e p l o u g h i n g o f t h e c t m n t e r f a c ew h e r e a s t h e t o u g h e r T i C i s a b l e to a b r a d e t h e c o u n t e r f a c ee f f e c t i v e l y .

5 . C o n c l u s k m sA l u m i n i u m m a t r i x c o m p o s i t e s w i t h T i C reinforcement

hav e been p roduc ed by a nov e l l i qu i d r ou te r es u l t i ng i n un i -


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1 7 0 P, t . Shqm'ay l aL I W e ar 216 f t 998J 160--171

F i g . I I . W e a r d a m a g e o f A I - - 4C u a l l o y a n d c o m i r ~ s i l c s f i f ll o w i n g s l i d i n g w e a r . ! a ) A I- - 4 C u . s u r fa c e . 3 1 N l o a d ; ( b i A I - 4 C u , s u b s u r f a c e , ~ c t i o n , 7 8 N l o a d :I c ~ AI -- .. IC . 'u - I I ) T i C , ~ , ur l~ . tc e . 7 8 N h i n d ; ( d ~ A I - - - ~ ( ' u - I I I T i C , s u h s u r f a c e s e c t i o n . 7 8 N h i n d .

f l ) r m panicle distributions. Panicle additions have reducedthe wear rates of the composites and have delayed the lran-sition with load from low wear coefficients to higher wearcoefficients, l.ow wear rates were characmrised by thin. stabletransfer layers and an almost uniform wear coefficient(an mnd I.I I0 ~) regardless ol'the alloy type. The A356alloy reinh~rced with 10 vol.r;~ TiC had the highest hardnessof all the materials examined and thus had the lowest wearrates in the low wear regime, outperlbrnung the 15 vol.~7,SiC-reinli~rccd material. However. SiC reinforcement wasable to delay the increase in wear coeflicienl to higher loads.An increase in the TiC pan icl e fraction to 2(1 vol.rTt resultedin furt her decrease.`` in wea r rate and further retarda tion of theload at which the wear coefficient increases.Particulate reinforcement of the alumin ium alloy resultedin wear of the .,,leel counter face, it was gen endl y found thatat a given volume fraction o f reinl;t)rcement, an increase inload resulted in an increase in composite wear rate and coun-ledac e wear rate. However. no such simple relationship wasobserved on altering the volume fraction of particles or par-t i c l e l y p e . The wear rate.` of the compo sites and counterl' accshave been rationalised in terms of the composite microstruc-lures and t~perating wear mechani:,~ns. When b olh comp ositeand counterface wear is considered, reinlorcement reducesthe overall wear rate of the system; however, high volumefractions may cau.~e more severe wear o f the counter face than

lower volume | factio ns and evidence has been presented thatindicates that an optimum volume fraction lot low systemwear exists.

Acknowledgemen t sThe authors gratefully ackn owledge the assistance of the

London and Scandina vian Metallurgical Co l.td. Rotherhamin Ibis programme .f research, and of Alex Karantzalis lotmetal Iogkaphy.

ReferencesI I I B . M a n i , ,h r ~ y . I L V c n k a t a r a , n a n . V . V . B h a , m p r a s a d . Y . R . M - h . ' , ja n .

( i . S u t ; d : tr a r a ja n + " l' h c e f f e c t O f p a ) l i c l c r c h l f o r c e m e l l l o l l t h e s l i d i n g~ c ~ ll ~ " ] a ~ i , r o f a l l . n ' l | i f l i u n l I l l a l r i x c t u n l ~ + x i te s . M e l a l l . T r a n s . A 2 3

1 9t }2 ~ " 8 3 3 - " 8 4 7 .1 21 Z . Y . M a . Y . N . I . i m L + . Y . Z + / h a n g . Y . X . I + u, J . B i . S l i d i n g w e a r

hehav i l~um"o f S i C p a r l i l r e i n l ' o r c e d - .2 11 24 l u m i n i u m a l l o y o m i ' ~ .' ~ il e s .M a l C r + S ' i . " ]' c1 1 . 1 2 ( I ~ ) t ) ~ j 7 5 1 - 7 5 ( ~ .

13 1 B . N . I ~ r a , lf i la B i , . B . S . R a n m . ', e. ', h, M . K . S u n , p p a , D r y s l i d i n g w e a r o fA 3 5 { ~ - A I - S i C r o n l l ~ . ,, i l . -, . w e a r 1 5 7 I 1 ~ ,~ } 2 1 2 ~ . ) 5 - 3 ( b t .

1 4 t i i . v c , ~k : r a r a m : m. ( ; . s u n d a r ; , r a j a n . T h e , , , l i d i l l g wL . - a r ~ h a v i o u r o f A I -S i C p m l k ' u l a l coml~si lcs - - I . M a c r o l ~ h a v i o u r . A l a M a t e r . 4 -1t I ~ )t~ 6 i 4 5 1 - 4 6 { ) .


12/12

P.H. Shilm'~O" el al. I Wear 2 1 6 ~19~8A If~7-171 17 1[ 5 1 B . V e n k a t a r a m a n , G . S u n d a r a r a j a n , T h e s l i d i n g w e a r h e h a v i o u r o f A I -

S i C p a r l ic u t a te c o m p o s i t e s - - I I . T h e c h a r a c te r i za t i o n o f s u h s u r f a c ede fo rm a t i on a nd c , wre l a t i on wi t h we a r be ha vkm r , Ac ua Ma t e r . 441 1 9 9 6 ) 4 6 1 - 4 7 3 .

[ 6 1 A . T . Al pa s , .I . Zha n g , W e a r r a t e t r a n s i ti (m s i n c a s t a l um i n i u m -s i l i c ona l l oys r e i n fo rc e d w i t h S i C pa r t i c l e s , S c r ip t a Me t a l l . Ma t e r . 26 | 1 ~ ) 9 2 )5 0 5 - 5 O 9 .171 A. T . Al pa s , J . : /: h a ng . E f fe c t o f S i C pa t l i c u l a t e r e i n fo rc e m e n t on t hed r y s l id i n g w e a r o f a l u m i n i u m - s i l i c ( m a l lo y s ( A 3 5 6 L W e a r 1 55( t 9 9 2 ) 8 3 - 1 0 4 .

181 M. B a t , Q . . Xu e . H , Gun . R e c i p r (x :a l s l i d i ng we a r o f S i C F a r t i c l ere i n fo rc e d AI - -, C u a l um i n i um m a t r i x c om pos i t e s a ga i n s t s t a i n l e s s s t e e l .h i gh s p e e d 1oo1 s t e e l a nd c e ra m i c s - - I . T r i t x f l og ic a l p rope r t i e s a ndc o n s t r u c t io n o f t r i b o - m a p s . W e a r 1 9 5 ( 1 9 9 6 ) 1 5 2 - 1 6 1 .

191 M. B a t , Q . X ue . H . Gun , R e c i l m ~ : a l s l id i ng we a r o f S i C pa n i c l ere i n fo rc e d AI - -C u a l um i n i um m a t r i x c om po s i t e s a ga i n s t s t a i n l e s s s t e e l .h i gh s pe e d t oo l s t e e l a nd c e ra m i c s ~ t l . W e a r n~ c ha n i s m s , W e a r 194( 1 9 9 6 ) 1 2 6 - 1 3 6 .

I IOI A . S a t o , R . Me hra h i a n , A l u m i n i um m a t r i x c om p t ~ i t e s : F a b r i c a t i onand prop ert ie s , M ela l l . Trans . B 7 I 1976 } 443--45 I .

I l I I A . W a ng , H . J . R a c k . T ra ns i t i on w e a r be h a v i o r o f S i C pa r l i c u l a t e a ndS i C w h i s ke r r e i n fo rc e d 7091 AI m e t a l m a t r i x c om l x ) s i t e s , Ma t e r. S c i .Eng . A2 47 ( 1991 ) 211 -22 4 .

[121 S . W i l s on . A , T . Al pa s . E f fe c t o f t e m pe ra t u re on t he s l i d i ng we a rp e r f m ' m a n e e o f A I a l l o y s a n d A I m a t r ix c o m p o s i t e s , W e a r 1 9 6 ( I t~.76)2 7 0 - 2 7 8 ,[ 131 A . M a r t i n . M, A. M a r t i ne t . J . LLorc a , W e a r o f S i C re i n fo rc e d AI - m a t r i xc om l x~ s i l e s i n t he t e m pe ra t u re r a nge 20 - 200 C , W e a r I t ~ 3 (199 6 )169--179.

] 141 S . C hu ng , B . H. H wa ng , A m i e n ) s t ruc t u ra l s t udy o f Ih~ we a r be ha v i ou ro f S i C p / A I c o m p o s i t e s . T r i b o l o g y I n t . 27 ( 1 9 9 4 ) , ~ ) 7 -3 1 4 .

1151 F , M, Hu s k i ng . F , F o l ga r P o r t i l lo , R . W u nde r l i n . R . M e hra b i a n .C o m l ~ s i t e s o f a l u m i n i u m a l l o y s: f a b r i e a li o n a n d w e a r I ~ h a v i o u r . J.Ma t e r . S c i . 17 q 1982 ) 47 7 -49 8 .

I 161 A . P . S a nn i n o . H J , R a c k , T r i lm f lt )g i ca l i nve s l i ga t i on o f 21109 AI -20vo l ~ S i C p / 1 7 -4 P H ~ P : tr l I . C om l x~ s i t e pe r fo rm a nc e . W e a r I177( l ~ f ~ ) 1 5 1 -1 5 9 .

I 1 7 1 A. P . S a nn i no . H J . R a c k , T r i bo l ug i c a l i nve s t i ga t i on o f 20 i l tl A | -2 I )v o V h S iC k , /1 7 - 4 P H - - P a n I . C t m n t e r p a n l ~ r t o r m a n c e . W e a r I ~( 1 9 9 6 ) 2 0 2 - 2 ( 1 6 .

] 18[ S J . L i n . C . A. L i n , G . A. W u . J. L . Horng . S l i d i ng v,e a r , f f A l _ , O , / 6 0 6 lAI c om po s i t e . J. Ma t e r . S c i . 31 (19 96 ) 348 I -3 . 1, ~ 6.

[ 191 M. N a ra ya n , M . K. S u ra pp a , B . N. P ram i l, ', B a t , Dry s l i d i ng we a r o f AIa l loy 2()24-A1:O~ part ic le meta l m;i t r ix compo.~i te s , W ear IX I-IN 3( 1995 ) 563--570.

120 ] A . P . S a nn i no , H , J . R a c k , D ry s l i d i t |g we a r o f d i , ~ on t i nuo us l yr e i tt f o r cc d a l u m i n i u m c o m p o s i t e s : r e v i e w an d d i . wus s i on . W e a r 189( 1 9 9 5 ) 1-19 .

[ 21 ] A. Wa ng, H J . Rack , A s ta t i s t ica l m(~Jl f l )r s l id ing w ear ~f rac ial ,, , inm e l a l / c ~ m p o s i t e s y s t e m s , A c t a M c t a ll . M a t e r. 4 0 1 1 9 9 2 ) 2 3 0 1 - 2 3 0 5 .

1221 I . M. Hu t c h i ngs . T r i l ~ f l og i e a l p rope r t i e s o f m e t a l m a t r i x c om pos i t e s .Ma t e r . S e t . Te c h . l O ( I ~ 4 ! 513 -517 .

1 2 31 R J . A r s e n a u l t, S . B . W u . A c o m p a r is ~ m o f P M v.~ m a t e d S i C / A Ic om pos i t e s , S c r i p t a Me t a l l . 22 ( t 1988 ) 767 -772 .

1241 X. Ni . T . N . B a ke r . M i c m s t ruc t u re a nd m e c ha n i c a l p rope r t i e s o l" S a f l i l ' / AA 6061 m e t a l m a t r i x c ~ m p os i l e s , i n: A . P t ~ ur s ar ti p a nd K .S t re e t ( Eds . ) Te n t h In t e rna t i ona l C on l i : r e nc e a n C o m p os i t e m a t e r i a l s ,V~ d . I I , W h i s t l e r , C a na da . 191 )5 . W ~ d he a d P ub l i s h i ng . C a m br i dge .I l K , pp . 3 7 7 - 3 8 4 .

1251 A. Mor t c ns e n . In t e r l a c i a l phe n t )m e na in the s o l i d i l ic a t i on p roc e s s i n go f m e t a l m a t r i x c ounp~ s i te s , Ma t e r . S c i . Eng . AI3 5 ( 1991 ) I - I I .

1261 D.J . Llo yd. H . La ga c e , A . Mc Le t n l . P . L . Muf t i s . Mi c ro s l ruc t unda s pe c t s o f a l um i n i um -s i l i c on c a rh i de c t )m p t ~ s i t e s p roduc e d by acas t ing m etho d, Mate r . S~.' i. Eng . A10 7 ( 19891 7 3-8(I .

| 2 7 1 P . S. M , h a m y . J . E . ( ; m z l e s k i . M e c h a n i s m o f g r a i n r e f i n ~ m e m i na l um i n i um . Ac t a M e t a l l, 43 ( 19951 20OI -2012 .1281C . A. C a ra c os t a s . W . A. C h i t i n . M, E . F i ne , H , S . C hc ng , W e a rm e c ha n i s m s du r i ng l u l wi c a t e d s l i d i ng c t m l ac t o f X D 2024-AI/ 'T ' iB 2

meta l ma t r ix com lx)s i te s aga ins t s tee l . , t~c ripta [~ .2l~'d l. Mate r . 27( I t~2 1 167-17..2 ,

129 ] A , R . Ke nn e dy . D . G. M c C a r l ne y . J . V . W t ~ rd , Hona > ge ne i m s m e t a lm a t r i x c o m l x~ i t c s p t t ~ u c c d b '. ' ~ nm ~ Ji li cd s l it - c a s t i ng t e c hn i que , i n :F . H . F r o e s . C . S u r y a n : w a ya n a an d C . M . W a n d c k ~ e ~Eds . ) S yn t he s i s /P roc e s s i ng o f ~ ; gn t we i gh t m e t a l l i c m a l e r i a ls , TM S . W a r re nda t e . P A.1995. ~ p . 261 -27 3 .13o I A . R . K gm ~ : dy . S . A . L (~ c kye r. D . G. Me C a r l nvy . , I. V . W (~ d . ' ] ' h em i e ro s t ruc t u re a nd m e c ha n i c a l p ra pv r l i e s o f l un 'm ~ ge ne c vus e a s tM M C s. i n : A , P o u rsa n ip a n d K . S t re e t (E d s . j Te n t h I n le rn a t km a iConferen ce ~m Com posi te m ater ia ls . Vo l , !1 . Wh ist le r . Canada. 1995.W 4 ~d h e a d P u b l i sh in g , C a m b r id g e , U K , p p . 4 5 7 -4 6 4 .

[ 3 1 I C .C . D e g n a n . P r o c e s s i n g a n d w e a r p r ( ~ r t i e s ~ f a ( w . ' n ) c F m i c u l a t cre i n f i )r c e d f e r rous ba . ~ d m e t a l m a l r i x c om p os i t e . P h . D . The s i s , t 9q6 .Un i ve r s i t y o f N~ n t i ngha m .[ 32 [ J . C . E h r s t rom , W . H. C t ~ f l . Mi g ra t i on o f pa r t i c l e s du r i ng e x lru si cwt o fmeta l ma t r ix co ml ~s i te s . J , Mate r . ,~ i . LOl l . 7 ( !%~8 ) .578-5110.

1331 HS , Ave ry . An a na l y s i s o f t he rubbe r whe e l a bn t s km l e f t . i n : S . K .R h e L . A . W . R u f f a n d K . C . l . m k , m a ! E d s . ) . P n ~ I n t . C o n L On W e a r,) t" Ma t e r i a l s . AS M E. Ne w V~ wk . i ( ~ I , p p . 3 6 7 - 3 7 8 ,

134 ] R . L , De n i s . C . S ub ra m a n i a n . J. M. Yc l l up , Abra ,, 4ve we a r o fc m npo s i t ec oa t i ngs i n a s a nd s l u r ry e nv i ron m e n t . W e a r 2 t ). ~- -2 tM ( I t ~ 7 ) 119 --128.

mogr a , ~P h i l i p S h i p w a y g r a d u a t e d i n 19 '~ 9 w i t h a B . A . d e g r e e i nM a t e r i a l s S c i e n c e a n d M e t a l l u r g y f r o m t h e U n i v e r s i t y o fC a m b r i d g e , a n d w a s a w a r d e d h i s P h . D . f r o m t h e . sa m e u n i -v e r s i t y i n 1 9 9 3 f o r w o r k o n t h e e r o s i o n o f b r i t t l e m a t e r i a l s b ys o l i d p a r t i c l e i m p a c t . S i n c e 1 9 9 4 h e h a s b e e n a l e c t u r e r i n t h eD e p a r t m e n t o f M a t e r i a l s E n g i n e e r i n g a n d M a t e r i a l s D e s i g na t t h e U n i v e r s i t y o f N o t t i n g h a m . H i s c u r r e n t r e , ~ a r c h i n t e re s t si n c l u d e d e v e lo p m e n t o f w e a r t e st m e t h o d o l o g i e s , w e a rb e h a v i o u r o f m a t e r i a l s ( e s p e c i a l l y a l u m i n i u m a n d f e r ro u sb a s e d M M C s . c e r m e t s a n d H V O F s p r a y e d c o a t in g s ) a n d t h e i rs t r u c t u r e - t r i b o l o g i c a l p r o p e r t y r e l a t i o n s ,A n d r e w K e n n e d y g r a d u a t e d i n 1 9 8 9 w i t h a B . E n g . d e g r e e i nM a t e r i a l s S c i e n c e a n d E n g i n e e r i n g f r o m I m p e r i a l C o l l e g e ,1 o l u J o n a n d w a s a w a r d e d h i s P h .D . f r o m t h e U n i v e r s i t y o fC a m b r i d g e i n 1 9 93 f o r w o r k o n r e i n f o r c e m e n t , ' e d i s tr i b u t i o nd u r i n g t h e s o l i d i f i c a t io n p r o c e s s i n g o f m e t a l m a t r i x c o m p o s -i te s . S i n c e 1 9 9 4 h e h a s b e e n a l e c t u r e r i n t h e D e p a r t m e n t o fM a t e r i a l s E n g i n e e r i n g a n d M a t e r i a l s D e s i g n a t t h e U n i v e r s i t yo f N o t t in g h a m . H i s current re .a rc h interests i n e h t d e d e v e l -o p i n g n o v e l m a n u f a c t u r i n g m e t h o d s f i) r M M C s , m e c h a n i s m so f g r a i n r e f i n e m e n t i n l i q u id m e t a l s , i n te d ' a c ia l p h e n o m e n ai n m e t a l - c e r a m i c s y s t e m s a n d t h e w e t t i n g o f s o l i d s b y l iq u i dm e t a l s .T o n y W i l k e s g r a d u a t e d i n 1 9 9 7 w i t h a B . E n g . d e g r e e i nM e c h a n i c a l D e s i g n , M a t e r i a l s a n d M a n u f a c t u r e f r o m th e U n i -v e r s i ty o f N o t t i n g h a m . H e i s p r e s e n t l y a p r o j e c t m a n a g e r w i t hM i t s u i B a b c o c k ,

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