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Properties and structures of mechanically alloyed and hot consolidated titanium-silicon and tungsten-silicon powder compacts
Mechanical alloying PROPERTIES AND STRUCTURES OF MECHANICALLY ALLOYED AND HOT CONSOLIDATED TITANIUM-SILICON AND TUNGSTEN-SILICON POWDER COMPACTS
J-H, A h n et al (Korea Inst, of Machinery a n d Metals, Changwon, Korea). A study of MA of elemental Ti-Si a n d WSi powder m i x t u r e s was described, MA was f o l l o w e d by h o t p r e s s i n g a n d h e a t treatment. T h e MA p o w d e r s were a m o r p h o u s or microcrystalline a n d t h e structures of t h e processed c o m p a c t s were described a n d c o m p a r e d with conventional PM materials. The a d v a n t a g e s of using MA were outlined. SURFACE MODIFICATION OF POWDER MATERIALS
M.Q.Lu et al (Academia Sincia, Shenyang, China). Studies of surface effects in m e c h a n i c a l l y alloyed V, Nb a n d TiNi p o w d e r s were described. P r o p e r t i e s of powders with modified surfaces were described a n d it was suggested t h a t use of these could give improved properties in processed materials.
Vladivostok, Russia). The m e c h a n o c h e m i c a l technology for t h e p r e p a r a t i o n of ultrafine W a n d WC powders was described. Structures a n d properties of t h e powders were given. LIQUID PHASE SINTERING OF HIGH DENSITY AND S T R E N G T H HIGH SPEED STEELS
G. G r e e t h a m (Manganese Bronze Powder Metals Group, Ipswich, UK). Addition of Cu2P was r e p o r t e d to e n a b l e HSS to be liquid p h a s e sintered at 115°C in v a c u u m or cracked a m m o n i a to densities of 98 to 100%. The alloys could be h e a t t r e a t e d a n d transverse r u p t u r e s t r e n g t h of 2 GPa was reported. Process details, to e n s u r e high density, were given. The s i n t e r i n g t e m p e r a t u r e allowed belt furnace sintering. CHARACTERISTICS OF MECHANOCHEMICAL SYNTHESIS OF TITANIUM CARBIDE WITH AND WITHOUT NICKEL
V.N. Vasilenko (Far East Polytechnical Inst., Vladivostok, Russia). P r e p a r a t i o n of TiC a n d a (Ti-12%Ni)C, using MA, was described. Factors affecting carbide f o r m a t i o n were e s t a b l i s h e d a n d structures a n d properties described.
MECHANOCHEMICAL T E C H N I Q U E S FOR PREPARATION OF FINE POWDERS
Compaction modelling and simulation
V.I. Lapshin (Positron Corp, St. Petersburg, Russia). It was reported t h a t MA h a d been used in t h e p r e p a r a t i o n of t i t a n a t e s a n d niobiates. Particle sizes down to 0.01 to 0.1 nm, with high c o n c e n t r a t i o n s of p o i n t defects a n d considerable lattice distortion, were obtained. Sintering was shown to be v o l u m e self-diffusion c o n t r o l l e d a t all stages.
E F F E C T OF S T R E S S STATE AND COLD PLASTIC DEFORMATION ON CONSOLIDATION OF POROUS MATERIALS
Refractory metals and hard metals USE OF HIGH S P E E D S T E E L S FOR D I E S E L E N G I N E VALVE SEATS
T. Kobayashi et ai (Mitsubishi Materials Corp, Nagata, J a p a n ) . The need for greater durability in diesel engine valve seats was noted. The use of PM high speed steels, processed to full density, was described use being m a d e of increased alloying a n d densification. Evaluation, in a 3.51 e n g i n e , w a s r e p o r t e d to show durability. MECHANOCHEMICAL TECHNOLOGY FOR PREPARATION OF ULTRAFINE T U N G S T E N AND T U N G S T E N CARBIDE POWDERS
V.P. Reva (Far E a s t Polytechnical Inst.,
54 MPR July/August 1994
F. Grosman, J. Lukowski (Silesian Technical University, Kayowice, Poland). An investigation of plastic deformation of Al powder containing a h a r d phase, Si, was described. The m e c h a n i s m s of 'closing' and 'welding', were identified from microstructure related to material discontinuities. The conditions required to p e r m i t d e t e r m i n a t i o n of t h e effects of deformation compactions and densification were established. F u n c t i o n s describing the relationships between density a n d applied stress a n d stress rate were worked out. SHOCK COMPACTION OF ALUMINIUM ALLOY S P H E R E S
M. Vukcevic et ai (University of Podgorica, Belgrade, Yugoslavia). The m e c h a n i s m s of shock consolidation of A1 a n d A1-Li, Al-Mg-Si a n d AI-Mg-Cu alloys were studied using measured p r o p e r t i e s . P o w d e r s were h o t or cold c o m p a c t e d a n d m i c r o s t r u c t u r a l evolution was d e t e r m i n e d by electron microscopy. The mass t r a n s f e r m e c h a n i s m s for densification to a n o n - p o r o u s condition was analysed.
N e w non-ferrous alloys USE OF QUADRUPOLE MASS SPECTROSCOPY IN S T U D I E S OF GAS E N T R A P M E N T A N D EVOLUTION
J.L. Esrtrada, J.Duszczyk (Technical University, Delft, The N e t h e r l a n d s ) . Aspects of gaseous evolution, d u r i n g d e g a s s i n g of p o r o u s Al samples, u s i n g mass spectroscopy, were described. T e m p e r a t u r e was shown to be t h e critical f a c t o r c o n t r o l l i n g gas d e s o r p t i o n . The diffusion of A1 t h r o u g h t h e oxide film is c o n s i d e r e d to e x p l a i n t h e k i n e t i c s of degassing by displacing m o i s t u r e a n d H in t h e film consisting of AI203 a n d MgO. T h e r m o d y n a m i c s were used to show t h a t MgO reacts with w a t e r v a p o u r in preference to A1203. ANALYSIS OF SURFACE OXIDES ON ALUMINIUM ALLOYS BY A U G E R ELECTRON SPECTROSCOPY
J.L. Esrtrada, J. Duszczyk (Technical University, Delft, The N e t h e r l a n d s ) .It was r e p o r t e d t h a t Auger spectroscopy h a d been used to investigate t h e oxide films on t e r n a r y A1-Si alloys with t h e objective of optimizing a t o m i z a t i o n powder processing conditions with respect to powder morphology, specific surface, oxide thickness and 0 content. Inert gas atomization was shown to produce p o w d e r s w i t h s m a l l e r specific surface, lower 0 c o n t e n t a n d t h i n n e r oxide films. SUPERPLASTIC BEHAVIOUR AT HIGH STRAIN RATES IN ALUMINIUM B A S E D ALLOYS
IC Higashi (University of Osaka Prefecture, Osaka, J a p a n ) . S u p e r p l a s t i c i t y w a s r e p o r t e d to b e e x h i b i t e d by a range of PM A1 alloys w h e n deformed at high s t r a i n rates. Alloys were fine grained a n d it was shown t h a t as t h e grain size d i m i n i s h e d t h e s t r a i n rate for superplasticity increased. It was e m p h a s i z e d t h a t a fine grain size is a prerequisite for superplasticity. MECHANICAL P R O P E R T I E S OF ALUMINIUM-NICKEL ALLOYS WITH TRANSITION METAL A N D MISCHMETAL
IC Higashi (University of Osaka Prefecture, Osaka, J a p a n ) . It w a s r e p o r t e d t h a t PM AI-Ni-ZrMischmetal alloys, made from high p r e s s u r e gas atomized powders, e x h i b i t e d h i g h e r v a l u e s of t e n s i l e s t r e n g t h a n d Young's m o d u l u s in t h e r a n g e a m b i e n t t e m p e r a t u r e to 200°C t h a n conventional alloys. This was a t t r i b u t e d to h o m o g e n e o u s dispersion of fine particles (15 to 65 n m ) in a fine grained A1 rich matrix.
J-H, A h n et al (Korea Inst, of Machinery a n d Metals, Changwon, Korea). A study of MA of elemental Ti-Si a n d WSi powder m i x t u r e s was described, MA was f o l l o w e d by h o t p r e s s i n g a n d h e a t treatment. T h e MA p o w d e r s were a m o r p h o u s or microcrystalline a n d t h e structures of t h e processed c o m p a c t s were described a n d c o m p a r e d with conventional PM materials. The a d v a n t a g e s of using MA were outlined. SURFACE MODIFICATION OF POWDER MATERIALS
M.Q.Lu et al (Academia Sincia, Shenyang, China). Studies of surface effects in m e c h a n i c a l l y alloyed V, Nb a n d TiNi p o w d e r s were described. P r o p e r t i e s of powders with modified surfaces were described a n d it was suggested t h a t use of these could give improved properties in processed materials.
Vladivostok, Russia). The m e c h a n o c h e m i c a l technology for t h e p r e p a r a t i o n of ultrafine W a n d WC powders was described. Structures a n d properties of t h e powders were given. LIQUID PHASE SINTERING OF HIGH DENSITY AND S T R E N G T H HIGH SPEED STEELS
G. G r e e t h a m (Manganese Bronze Powder Metals Group, Ipswich, UK). Addition of Cu2P was r e p o r t e d to e n a b l e HSS to be liquid p h a s e sintered at 115°C in v a c u u m or cracked a m m o n i a to densities of 98 to 100%. The alloys could be h e a t t r e a t e d a n d transverse r u p t u r e s t r e n g t h of 2 GPa was reported. Process details, to e n s u r e high density, were given. The s i n t e r i n g t e m p e r a t u r e allowed belt furnace sintering. CHARACTERISTICS OF MECHANOCHEMICAL SYNTHESIS OF TITANIUM CARBIDE WITH AND WITHOUT NICKEL
V.N. Vasilenko (Far East Polytechnical Inst., Vladivostok, Russia). P r e p a r a t i o n of TiC a n d a (Ti-12%Ni)C, using MA, was described. Factors affecting carbide f o r m a t i o n were e s t a b l i s h e d a n d structures a n d properties described.
MECHANOCHEMICAL T E C H N I Q U E S FOR PREPARATION OF FINE POWDERS
Compaction modelling and simulation
V.I. Lapshin (Positron Corp, St. Petersburg, Russia). It was reported t h a t MA h a d been used in t h e p r e p a r a t i o n of t i t a n a t e s a n d niobiates. Particle sizes down to 0.01 to 0.1 nm, with high c o n c e n t r a t i o n s of p o i n t defects a n d considerable lattice distortion, were obtained. Sintering was shown to be v o l u m e self-diffusion c o n t r o l l e d a t all stages.
E F F E C T OF S T R E S S STATE AND COLD PLASTIC DEFORMATION ON CONSOLIDATION OF POROUS MATERIALS
Refractory metals and hard metals USE OF HIGH S P E E D S T E E L S FOR D I E S E L E N G I N E VALVE SEATS
T. Kobayashi et ai (Mitsubishi Materials Corp, Nagata, J a p a n ) . The need for greater durability in diesel engine valve seats was noted. The use of PM high speed steels, processed to full density, was described use being m a d e of increased alloying a n d densification. Evaluation, in a 3.51 e n g i n e , w a s r e p o r t e d to show durability. MECHANOCHEMICAL TECHNOLOGY FOR PREPARATION OF ULTRAFINE T U N G S T E N AND T U N G S T E N CARBIDE POWDERS
V.P. Reva (Far E a s t Polytechnical Inst.,
54 MPR July/August 1994
F. Grosman, J. Lukowski (Silesian Technical University, Kayowice, Poland). An investigation of plastic deformation of Al powder containing a h a r d phase, Si, was described. The m e c h a n i s m s of 'closing' and 'welding', were identified from microstructure related to material discontinuities. The conditions required to p e r m i t d e t e r m i n a t i o n of t h e effects of deformation compactions and densification were established. F u n c t i o n s describing the relationships between density a n d applied stress a n d stress rate were worked out. SHOCK COMPACTION OF ALUMINIUM ALLOY S P H E R E S
M. Vukcevic et ai (University of Podgorica, Belgrade, Yugoslavia). The m e c h a n i s m s of shock consolidation of A1 a n d A1-Li, Al-Mg-Si a n d AI-Mg-Cu alloys were studied using measured p r o p e r t i e s . P o w d e r s were h o t or cold c o m p a c t e d a n d m i c r o s t r u c t u r a l evolution was d e t e r m i n e d by electron microscopy. The mass t r a n s f e r m e c h a n i s m s for densification to a n o n - p o r o u s condition was analysed.
N e w non-ferrous alloys USE OF QUADRUPOLE MASS SPECTROSCOPY IN S T U D I E S OF GAS E N T R A P M E N T A N D EVOLUTION
J.L. Esrtrada, J.Duszczyk (Technical University, Delft, The N e t h e r l a n d s ) . Aspects of gaseous evolution, d u r i n g d e g a s s i n g of p o r o u s Al samples, u s i n g mass spectroscopy, were described. T e m p e r a t u r e was shown to be t h e critical f a c t o r c o n t r o l l i n g gas d e s o r p t i o n . The diffusion of A1 t h r o u g h t h e oxide film is c o n s i d e r e d to e x p l a i n t h e k i n e t i c s of degassing by displacing m o i s t u r e a n d H in t h e film consisting of AI203 a n d MgO. T h e r m o d y n a m i c s were used to show t h a t MgO reacts with w a t e r v a p o u r in preference to A1203. ANALYSIS OF SURFACE OXIDES ON ALUMINIUM ALLOYS BY A U G E R ELECTRON SPECTROSCOPY
J.L. Esrtrada, J. Duszczyk (Technical University, Delft, The N e t h e r l a n d s ) .It was r e p o r t e d t h a t Auger spectroscopy h a d been used to investigate t h e oxide films on t e r n a r y A1-Si alloys with t h e objective of optimizing a t o m i z a t i o n powder processing conditions with respect to powder morphology, specific surface, oxide thickness and 0 content. Inert gas atomization was shown to produce p o w d e r s w i t h s m a l l e r specific surface, lower 0 c o n t e n t a n d t h i n n e r oxide films. SUPERPLASTIC BEHAVIOUR AT HIGH STRAIN RATES IN ALUMINIUM B A S E D ALLOYS
IC Higashi (University of Osaka Prefecture, Osaka, J a p a n ) . S u p e r p l a s t i c i t y w a s r e p o r t e d to b e e x h i b i t e d by a range of PM A1 alloys w h e n deformed at high s t r a i n rates. Alloys were fine grained a n d it was shown t h a t as t h e grain size d i m i n i s h e d t h e s t r a i n rate for superplasticity increased. It was e m p h a s i z e d t h a t a fine grain size is a prerequisite for superplasticity. MECHANICAL P R O P E R T I E S OF ALUMINIUM-NICKEL ALLOYS WITH TRANSITION METAL A N D MISCHMETAL
IC Higashi (University of Osaka Prefecture, Osaka, J a p a n ) . It w a s r e p o r t e d t h a t PM AI-Ni-ZrMischmetal alloys, made from high p r e s s u r e gas atomized powders, e x h i b i t e d h i g h e r v a l u e s of t e n s i l e s t r e n g t h a n d Young's m o d u l u s in t h e r a n g e a m b i e n t t e m p e r a t u r e to 200°C t h a n conventional alloys. This was a t t r i b u t e d to h o m o g e n e o u s dispersion of fine particles (15 to 65 n m ) in a fine grained A1 rich matrix.