Preparation of nickelalumina composites using an electroless plating technique

Preparation of nickelalumina composites using an electroless plating technique

PM LITERATURE REVIEW Powder forging Sintering mechanisms USE O F ROTARY F O R G I N G FOR POWDER COMPACTION A N D DENSIFICATION OF PREFORMS ROLE...

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PM

LITERATURE

REVIEW

Powder forging

Sintering mechanisms

USE O F ROTARY F O R G I N G FOR POWDER COMPACTION A N D DENSIFICATION OF PREFORMS

ROLE OF B I N D E R M E L T I N G A N D CRYSTALLIZATION IN STRUCTURAL EVOLUTION IN HARD METALS A N D HEAVY ALLOYS

S. D o m s a et al (Technical University of Cluj-Napoca, Romania). It was r e p o r t e d t h a t heavy compaction, 86 to 91%, h a d been a t t a i n e d by rotary cold forging a n d very heavy compaction, 93 to 97%, by h o t forging of s i n t e r e d preforms. Densification, which was studied q u a n t i t a t i v e l y as f u n c t i o n s of p r o c e s s conditions, was discussed. COMPARISON OF PM P R O C E S S I N G FOR P R O D U C T I O N O F ALUMINIUM ALLOY AUTOMOTIVE PARTS Y. Bienvenu et al (Ecole des Mines de Paris, Paris, France) A comparison of different PM p r o c e s s e s for p r o d u c t i o n of a u t o m o t i v e parts in A1-20wt%Si-5%Fe-2%Ni was reported. Consolidation, rheology, microstructures and properties were considered. The optimum combination of properties was o b t a i n e d by powder e x t r u s i o n or p o w d e r forging.

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K.S. Cherniavsky et al (Refractory a n d Hard Metals Inst., Moscow, Russia) Structural evolution d u r i n g liquid p h a s e s i n t e r i n g of WC-Co a n d W-Ni-Fe w a s investigated. Pore e l i m i n a t i o n a n d grain s h a p e c h a n g e s were considered. In t h e case of WC-Co the predominant m e c h a n i s m is s h o w n to b e p r e c i p i t a t i o n a t existing nucleii. In W-Fe-Ni i n d e p e n d e n t nucleation of W is s h o w n to be possible. The differences in t h e m e c h a n i s m s were discussed a n d were considered to be d u e to differences in crystal a n i s t r o p y between t h e two systems. E M B R I T T L E M E N T OF S I N T E R E D T U N G S T E N ALLOYS ACTIVATED BY NICKEI~PHOSPHORUS X_ Zizhang et al (The PM Inst. of t h e Chinese Society of Metals) A n i n v e s t i g a t i o n of e m b r i t t l e m e n t , c a u s e d by Ni-P s i n t e r i n g a c t i v a t o r , of sintered W was described. The main f a c t o r s i n f l u e n c i n g e m b r i t t l e m e n t were

s h o w n to be a c o m b i n e d effect of grain b o u n d a r y particles of W f o u n d in t h e final s t a g e s of l i q u i d p h a s e s i n t e r i n g a n d brittleness due to defects in t h e s t r u c t u r e of W-Ni second phase.

Metal matrix composites H I G H STRAIN RATE SUPERPLASTICITY IN PM A L U M I N I U M / S I L I C O N N I T R I D E PARTICLE C O M P O S I T E S M. Mabuchi et al ( I n d u s t r i a l Research Ins., Nagoya, J a p a n ) It was r e p o r t e d t h a t superplasticity h a d been detected in A1-20vol%SiaNa particle reinforced materials. The s u p e r p l a s t i c i t y was found a t s t r a i n r a t e s above 10 z per second a n d elongations u p to 620% were observed. P R E P A R A T I O N O F NICKEL-ALUMINA COMPOSITES USING AN E L E C T R O L E S S PLATING T E C H N I Q U E H. W a t a n a b l e et al ( A s h i k a g a Inst. of Technology, J a p a n ) The use of Ni p l a t e d A1203 powders to p r o d u c e a c o m p o s i t e by h o t pressing was described. It was s h o w n by optical a n d electron microscopy that the structure consisted of a dispersion of Ni particles in t h e matrix.

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