- Email: [email protected]
Controlled fracture forming of stainless steel-αaluminium composite fibres
Rapid solidification MATERIALS FOR THE DISC USED IN ROTATING DISC ATOMIZATION PROCESSES T. S a t o h et al ( G o v e r n m e n t I n d u s t r i a l Research Laboratory, Kyushi, J a p a n ) . The p r o p e r t i e s r e q u i r e d of t h e disc material used in rotating disc atomization machinery were identified as including good wettability, high h e a t a n d t h e r m a l shock resistance, high strength, low density a n d thermal conductivity and adequate machinability. It was r e p o r t e d t h a t a disc m a d e from Si3Na-BN h a d been used to p r e p a r e Cu-14% A1-3% Ni powder at a yield rate of 95%. At a low wettability with t h e disc, a disc with fins was used. A graphite disc was used to make A1, Cu or Zn base alloy powders at yeld rates of 50 to 60%. PRECIPITATION H A R D E N I N G AND MICROSTRUCTURE OF RAPIDLY SOLIDIFIED ALUMINIUUM ALLOYS B-S. You, W-W. P a r k ( K o r e a I n s t . of Machinery a n d Metals, Kyungnam, Korea). It was reported t h a t alloys of A1-Ti-Si a n d A1-Cr-Y, with a single dispersed p h a s e in a matrix, h a d been p r e p a r e d by RS techniques. Isochronal and isothermal p r e c i p i t a t i o n t r e a t m e n t s were u s e d to study t h e effects of m i n o r elements. The precipitation t r e a t m e n t s were used to study the effects of minor elements. The precipitates were shown to be tetragonal (Ti,Si)A13 a n d c u b i c A120Cr2Y. S t r o n g correlations between s t r u c t u r e a n d age h a r d e n i n g were demonstrated. STRUCTURES A N D MECHANICAL P R O P E R T I E S OF RAPIDLY S O L I D I F I E D A N D S I N T E R E D TERNARY MAGNESIUM-ZINC ALLOYS T. Sato et al (Nihon University, Chiba, Japan). An investigation of t h e structures a n d properties of Mg-6wt%Zn with a d d i t i o n s of Zr, Mn, Ni, Si a n d Ce was described. Highest h a r d n e s s e s were reported for t h e alloy with Ce a n d Zr. Tensile s t r e n g t h of 555 MPa was f o u n d in t h e alloy Mg-6% Zn-4.4% Ce0.4%Zr at room t e m p e r a t u r e a n d 188 MPa at 200°C.
Liquid phase sintering SINTERING OF SYSTEMS OF INTERACTING C O M P O N E N T S A.P. Savitskii (Russian Academy of Sciences, Moscow, Russia). New viewpoints concerning forces in sintering a n d definitions of p h e n o m e n a were p r e s e n t e d . Four classes of b i n a r y systems were identified based on volume changes. Laws governing volume changes were discussed a n d e x p e r i m e n t a l studies described. Criteria for selection of additives for volume change control were given.
50 MPR December 1993
GRAIN GROWTH DURING S I N T E R I N G OF TUNGSTEN-NICKEL ALLOYS T. Kohara, T. Ohira (Science University of Tokyo, Tokyo, J a p a n ) . An investigation of t h e sintering, at 155°C, of W-(3,7,15 or 30)wt%Ni, for various times, was described. The rate of W grain growth decreased with increase in Ni c o n t e n t a n d the W grain size increased with time. It was also found t h a t t h e grain growth was influenced by gravity being greater a t t h e lower end of specimens. MECHANICAL P R O P E R T I E S OF LIQUID PHASE S I N T E R E D 304L STAINLESS STEEL A. Sharon, D. Itzhak (Ben-Gurion University of t h e Negev, Beer-Sheeva, Israel). It was reported t h a t t h e liquid phase, formed form a Cu alloy powder a d d e d to 304L stainless steel, h a d an adverse effect on mechanical properties except elongation. I n v e s t i g a t i o n s of s t r u c t u r e / property relationships were described. LIQUID PHASE SINTERING OF SOME NICKEL BASE ALLOYS FOR HIGH S T R E N G T H AND OXIDATION RESISTANCE R.P.H. Fleming (University of Greenwich, Greenwich, UK). Studies of liquid p h a s e sintering of a range of Ni alloys, including Ni-Cr-Ta a n d Ni-Cr-Mo-W-TiC were described. Use was m a d e of a range of p r o d u c t i o n processes to yield alloys with solid solution strengthening, dispersion strengthening a n d p r e c i p i t a t i o n h a r d e n i n g . HIP w a s s h o w n to give alloys w i t h full density, improved mechanical properties and reduced grain size.
Metal matrix composites NANODISPERSOID STRENGTHENING OF METAL CERAMIC C O M P O S I T E S E. Hiihara et al (Osaka University, Osaka, Japan). It was reported t h a t Mo-ZrO2, Ni-Al~O3, MoSi2-SiC a n d o t h e r systems, in which t h e dispersed p h a s e was of n m dimensions, demonstrated improved mechanical properties. Investigations of fabrication, s t r u c t u r e a n d properties were described. E m p h a s i s was placed on t h e u n d e r s t a n d i n g of t h e effects of nano-sized dispersoids on mechanical properties. LIQUID PHASE SINTERING OF HIGH S P E E D STEELS WITH A D D I T I O N S OF PARTICULATE HARD CERAMICS A N D SOLID LUBRICANTS J.D. Bolton, A J . Gant (University of Bradford, Bradford, UIO. An investigation, with t h e objective of improving t h e wear performance of sintered
HSS u n d e r conditions of poor lubrication, by incorporation of h a r d ceramic particles a n d a solid lubricant, was described. The effects of t h e additives on sintering a n d m a t r i x / a d d i t i v e interactions were studied in order to optimize selection of additives. It was r e p o r t e d t h a t full d e n s i t y a n d satisfactory microstructures had been attained. MODIFICATION OF SURFACE OF SILICON CARBIDE BY SOL-GEL COATING Y.L. Liu, B. Kindl (Riso National Laboratory, Denmark). The use of a sol-gel t e c h n i q u e to apply a coating to SiC fibres was shown to improve t h e m e c h a n i c a l p r o p e r t i e s of A1-SiC composites. This was attributed to reduced interaction at t h e m a t r i x fibre interface. CONTROLLED FRACTURE FORMING OF STAINLESS STEEL-czALUMINIUM COMPOSITE FIBRES K. Tatsuzawa et al (University of Tokyo, Tokyo, J a p a n ) . It was reported that stainless steelcdA1203 c o m p o s i t e fibre h a d b e e n p r o d u c e d by controlled fracture forming which crushed the Q~A12O3 to sub micron sizes. The r e s u l t a n t m a t e r i a l could be sintered at ll00°C. The mechanical properties of the fibres were described. FABRICATION A N D P R O P E R T I E S OF ALUMINA WHISKERS AND ALUMINIUM METAL MATRIX C O M P O S I T E S B.K. Padhi (NALCO, Orissa, India). The p r o d u c t i o n of A1-A1203 w h i s k e r c o m p o s i t e s by CIP a n d s i n t e r i n g was described. Effects of p r o c e s s v a r i a b l e s were investigated and dimensional changes, structure and properties described. Structure/property relationships were discussed and the composites were said to offer high strength, corrosion a n d i m p a c t resistance. INTERFACES IN PM ALUMINIUM METAL MATRIX C O M P O S I T E S K. S u g a n u m a (National Defence Academy, Tokyo, J a p a n ) . An investigation of interfaces in 6061 A1 alloy-SiC composites was described. Solid s t a t e reaction was shown to produce an a m o r p h o u s interface reaction product. In a partial molten s t a t e this d i s s a p p e a r e d a n d direct m a t r i x / r e i n f o r c e m e n t contact was found. Fine "~A12O3 particles were observed which originated in t h e oxide film on the Al alloy powder. SUPERPLASTICITY IN ALUMINIUM NITRADE ALUMINIUM ALLOY COMPOSITES T. I m a i et al ( G o v e r n m e n t I n d u s t r i a l Research Intitute, Nagoya, J a p a n ) .
Liquid phase sintering SINTERING OF SYSTEMS OF INTERACTING C O M P O N E N T S A.P. Savitskii (Russian Academy of Sciences, Moscow, Russia). New viewpoints concerning forces in sintering a n d definitions of p h e n o m e n a were p r e s e n t e d . Four classes of b i n a r y systems were identified based on volume changes. Laws governing volume changes were discussed a n d e x p e r i m e n t a l studies described. Criteria for selection of additives for volume change control were given.
50 MPR December 1993
GRAIN GROWTH DURING S I N T E R I N G OF TUNGSTEN-NICKEL ALLOYS T. Kohara, T. Ohira (Science University of Tokyo, Tokyo, J a p a n ) . An investigation of t h e sintering, at 155°C, of W-(3,7,15 or 30)wt%Ni, for various times, was described. The rate of W grain growth decreased with increase in Ni c o n t e n t a n d the W grain size increased with time. It was also found t h a t t h e grain growth was influenced by gravity being greater a t t h e lower end of specimens. MECHANICAL P R O P E R T I E S OF LIQUID PHASE S I N T E R E D 304L STAINLESS STEEL A. Sharon, D. Itzhak (Ben-Gurion University of t h e Negev, Beer-Sheeva, Israel). It was reported t h a t t h e liquid phase, formed form a Cu alloy powder a d d e d to 304L stainless steel, h a d an adverse effect on mechanical properties except elongation. I n v e s t i g a t i o n s of s t r u c t u r e / property relationships were described. LIQUID PHASE SINTERING OF SOME NICKEL BASE ALLOYS FOR HIGH S T R E N G T H AND OXIDATION RESISTANCE R.P.H. Fleming (University of Greenwich, Greenwich, UK). Studies of liquid p h a s e sintering of a range of Ni alloys, including Ni-Cr-Ta a n d Ni-Cr-Mo-W-TiC were described. Use was m a d e of a range of p r o d u c t i o n processes to yield alloys with solid solution strengthening, dispersion strengthening a n d p r e c i p i t a t i o n h a r d e n i n g . HIP w a s s h o w n to give alloys w i t h full density, improved mechanical properties and reduced grain size.
Metal matrix composites NANODISPERSOID STRENGTHENING OF METAL CERAMIC C O M P O S I T E S E. Hiihara et al (Osaka University, Osaka, Japan). It was reported t h a t Mo-ZrO2, Ni-Al~O3, MoSi2-SiC a n d o t h e r systems, in which t h e dispersed p h a s e was of n m dimensions, demonstrated improved mechanical properties. Investigations of fabrication, s t r u c t u r e a n d properties were described. E m p h a s i s was placed on t h e u n d e r s t a n d i n g of t h e effects of nano-sized dispersoids on mechanical properties. LIQUID PHASE SINTERING OF HIGH S P E E D STEELS WITH A D D I T I O N S OF PARTICULATE HARD CERAMICS A N D SOLID LUBRICANTS J.D. Bolton, A J . Gant (University of Bradford, Bradford, UIO. An investigation, with t h e objective of improving t h e wear performance of sintered
HSS u n d e r conditions of poor lubrication, by incorporation of h a r d ceramic particles a n d a solid lubricant, was described. The effects of t h e additives on sintering a n d m a t r i x / a d d i t i v e interactions were studied in order to optimize selection of additives. It was r e p o r t e d t h a t full d e n s i t y a n d satisfactory microstructures had been attained. MODIFICATION OF SURFACE OF SILICON CARBIDE BY SOL-GEL COATING Y.L. Liu, B. Kindl (Riso National Laboratory, Denmark). The use of a sol-gel t e c h n i q u e to apply a coating to SiC fibres was shown to improve t h e m e c h a n i c a l p r o p e r t i e s of A1-SiC composites. This was attributed to reduced interaction at t h e m a t r i x fibre interface. CONTROLLED FRACTURE FORMING OF STAINLESS STEEL-czALUMINIUM COMPOSITE FIBRES K. Tatsuzawa et al (University of Tokyo, Tokyo, J a p a n ) . It was reported that stainless steelcdA1203 c o m p o s i t e fibre h a d b e e n p r o d u c e d by controlled fracture forming which crushed the Q~A12O3 to sub micron sizes. The r e s u l t a n t m a t e r i a l could be sintered at ll00°C. The mechanical properties of the fibres were described. FABRICATION A N D P R O P E R T I E S OF ALUMINA WHISKERS AND ALUMINIUM METAL MATRIX C O M P O S I T E S B.K. Padhi (NALCO, Orissa, India). The p r o d u c t i o n of A1-A1203 w h i s k e r c o m p o s i t e s by CIP a n d s i n t e r i n g was described. Effects of p r o c e s s v a r i a b l e s were investigated and dimensional changes, structure and properties described. Structure/property relationships were discussed and the composites were said to offer high strength, corrosion a n d i m p a c t resistance. INTERFACES IN PM ALUMINIUM METAL MATRIX C O M P O S I T E S K. S u g a n u m a (National Defence Academy, Tokyo, J a p a n ) . An investigation of interfaces in 6061 A1 alloy-SiC composites was described. Solid s t a t e reaction was shown to produce an a m o r p h o u s interface reaction product. In a partial molten s t a t e this d i s s a p p e a r e d a n d direct m a t r i x / r e i n f o r c e m e n t contact was found. Fine "~A12O3 particles were observed which originated in t h e oxide film on the Al alloy powder. SUPERPLASTICITY IN ALUMINIUM NITRADE ALUMINIUM ALLOY COMPOSITES T. I m a i et al ( G o v e r n m e n t I n d u s t r i a l Research Intitute, Nagoya, J a p a n ) .