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Thermal expansion and strength of invar-cordierite sintered cermet compacts
corrosion resistance and could be polished to high reflectivity and flatness.
CHARACTERISTICS A N D APPLICATIONS OF A N E W Fe-BASE HARD ALLOY
M. Hirano, H. Kawatani, (Kobe Steel, Japan), Kobelco Technology Review, No 9, 1990, 29-32. The production of a new hard alloy made from high speed steel powder (HSS) and 17% TiN and VC by high energy ball milling, CIP, sintering and HIP. The structure is reported to be a fine dispersion of the hard particles in a HSS matrix. The Rockwell hardness exceeds 72 Rc and bend strength is above 200 Kgf/mm 2. The life of punches made from the new alloy is claimed to be three times that of HSS.
S T R E N G T H A N D RESIDUAL S T R E S S E S IN C E M E N T E D C A R B I D E S S U B J E C T E D TO ABRASIVE PARTICLE T R E A T M E N T
K. Kamachi, T. Yamamoto, (Kinki University, Osaka, Japan), J. Japan Inst. of Metals, Vol 54, No 10, 1990, 1131-1135. In Japanese. The paper draws attention to the need to treat defects, such as voids which may cause fracture in cemented carbides, in a statistical manner. In this study, changes in fracture properties of cemented WC-(5 to 15%)Co, which had been subjected to bombardment by hard abrasive particles, were investigated. In particular, the effects of residual stresses, p r o d u c e d by t h e blasting media of differing hardness, on the fracture properties were considered. THERMAL E X P A N S I O N A N D S T R E N G T H O F INVAR43ORDIERITE S I N T E R E D C E R M E T COMPACTS
N. Ikeda, et al, (University of Tokyo, Japan),
J. Japan Inst. of Metals, Vol 54, No 10, 1990, 1136-1141. In Japanese. Sinterability, t h e r m a l expansion and t r a n s v e r s e r u p t u r e s t r e n g t h (TRS) of invar-cordierite compacts made from fine Ni, Fe a n d c o r d i e r i t e p o w d e r s w e r e measured in relationship to the amount of B added as a sintering aid. It was shown that at least 0.2wt%B is required to give an i m p r o v e m e n t in sinterability. T h e r m a l expansion was reduced by an increase in the proportion of cordierite but at the expense of a reduction in strength. CLASSIFICATION O F WC POWDERS FOR P R O D U C T I O N O F HARD ALLOYS
T.B. Gorbacheva, et al, Tsvetn. MetaU, No 3, 1990, 70-74. In Russian. A study was made of the effects of reduction temperatures of WO, and of the carburization temperature to WC, on the morphology, granularity, lattice perfection
and c o m p o s i t i o n of t h e WC p o w d e r s produced. Measurements were m a d e of p a r t i c l e size d i s t r i b u t i o n and specific surface for all stages in the production of WC from WO. The WC lattice was found to have a high degree of perfection. The impurity content of the WC declined with increase in carburization temperature. S I N T E R I N G O F HIGH S P E E D STEEL ( H S S ) POWDER COMPACTS
A.N. Shumilin, et al, (Moscow Inst. of Steel and Alloys, USSR), Izvestia E U.Z Chernaya Metall, No 3, 1990, 102-103. In Russian. A comparison is made of water and gas atomized HSS powders with respect to the production of sintered materials. Differences in compacting pressures were noted. Water atomized powders were said to have an advantage although coated with an oxide layer which must be reduced during sintering. The kinetics of the reduction were also studied. CUTTING P E R F O R M A N C E O F PM HIGH S P E E D STEELS ( H S S )
L. Zima, Strojfr. Vyroba, Vol 37, No 12, 1989, 45-48. In Czech. A study of the cutting performance of HSS is described. The effects of variables in p r e s s i n g a n d s i n t e r i n g on s t r u c t u r e , properties and cutting were investigated. PM high speed steels (HSS) were found to be comparable in efficiency with HSS made by melting and casting. In the case of face milling, PM HSS c o m p a r e d well w i t h cemented carbides. A S P E C T OF T H E P R O D U C T I O N OF F I N I S H E D P R O D U C T S MADE FROM HIGH S P E E D STEEL ( H S S ) POWDER
K-D. Lietzmann, et al, (Bergakademie, Frieberg, Germany), Neue HO:tte, Vol 35, No 7, 255-262. In German. A study was made of gas and water atomized high speed steel (HSS) powders and it is reported that the water atomized powders are rougher than the gas atomized. On pressing of the gas atomized powders there was greater movement of the powder in the die and this led to a greater incidence of cracking. D e n s i f i c a t i o n of t h e two powders was compared and it is suggested that in the case of the water atomized powders optimum densification is obtained by a combination of forging and rolling.
Intermetallic Materials rrH,III
H
II
MODELLING O F HIP CONSOLIDATION O F Ni A L U M I N I D E POWDERS
P~N. Wright, et al, (E.G. & G, Idaho Inc. Idaho Falls, USA), Powder Metallurgy, Vol 33, No 3, 1990, 253-259.
A model has been constructed for the HIP consolidation of Ni3A1 powders. The additive effects of plastic flow, power law creep, boundary diffusion and NabarroHerring and Goble creep are taken into account. HIP maps have been derived which d e s c r i b e t h e HIP c o n s o l i d a t i o n w i t h reasonable accuracy compared with experimental results. Finite element analysis was used as an extension to the HIP map approach.
P R O D U C T I O N OF N | T i SHAPE MEMORY ALLOYS ( S M A ) BY C O M B U S T I O N SYNTHESIS
M. Otaguchi, et al, (National Research Inst. for Metals, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 2, 1990, 214-223. In Japanese. The use of PM to produce NiTi shape memory alloys (SMA) with the objective of attaining closer control of composition is described. Small changes in composition result in large changes in SMA temperature. Combustion synthesis was used. The alloy was found to consist of 100% NiTi which could be HIPed to full density. Wire made from the alloy showed a SMA temperature of about IO0°C.
APPLICATION O F C O M B U S T I O N SYNTHESIS TO P R O D U C T I O N OF ZrNi INTERMETALLIC COMPOUND
C. Nashimura, et al, (National Research Inst. for Metals, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 5, 1990, 603-610. In English. ZrNi i n t e r m e t a l l i c c o m p o u n d s were produced by combustion synthesis and the effects of preheat temperature, in the range 25 to 400°C were studied. The product was porous when the preheat temperature was 100°C and was completely fused at 400°C. The products were found to contain ZrNi, ZrgNi11 and Zr2Ni according to composition of the powder mixture and the process conditions.
STRUCTURE AND P R O P E R T I E S OF Ti ALUMINIDE COMPACTS P R O D U C E D BY HOT P R E S S I N G MECHANICALLY ALLOYED POWDER
& Miyazaki, et al, (Sony Ltd, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 11, 1990, 1279-1283. In Japanese. A m i x t u r e c o n t a i n i n g 70at%Ti and 30%A1 were mechanically alloyed (MA) and hot pressed for 1 hour at 900°C. Near full density was attained. It was shown that the compact consisted of TiaAl with a mean grain size of 1.5~m. The alloy had high compressive strength and low ductility. Recrystallization and grain r e f i n e m e n t occurred during hot working at 900°C.
MPR May 1991 75
CHARACTERISTICS A N D APPLICATIONS OF A N E W Fe-BASE HARD ALLOY
M. Hirano, H. Kawatani, (Kobe Steel, Japan), Kobelco Technology Review, No 9, 1990, 29-32. The production of a new hard alloy made from high speed steel powder (HSS) and 17% TiN and VC by high energy ball milling, CIP, sintering and HIP. The structure is reported to be a fine dispersion of the hard particles in a HSS matrix. The Rockwell hardness exceeds 72 Rc and bend strength is above 200 Kgf/mm 2. The life of punches made from the new alloy is claimed to be three times that of HSS.
S T R E N G T H A N D RESIDUAL S T R E S S E S IN C E M E N T E D C A R B I D E S S U B J E C T E D TO ABRASIVE PARTICLE T R E A T M E N T
K. Kamachi, T. Yamamoto, (Kinki University, Osaka, Japan), J. Japan Inst. of Metals, Vol 54, No 10, 1990, 1131-1135. In Japanese. The paper draws attention to the need to treat defects, such as voids which may cause fracture in cemented carbides, in a statistical manner. In this study, changes in fracture properties of cemented WC-(5 to 15%)Co, which had been subjected to bombardment by hard abrasive particles, were investigated. In particular, the effects of residual stresses, p r o d u c e d by t h e blasting media of differing hardness, on the fracture properties were considered. THERMAL E X P A N S I O N A N D S T R E N G T H O F INVAR43ORDIERITE S I N T E R E D C E R M E T COMPACTS
N. Ikeda, et al, (University of Tokyo, Japan),
J. Japan Inst. of Metals, Vol 54, No 10, 1990, 1136-1141. In Japanese. Sinterability, t h e r m a l expansion and t r a n s v e r s e r u p t u r e s t r e n g t h (TRS) of invar-cordierite compacts made from fine Ni, Fe a n d c o r d i e r i t e p o w d e r s w e r e measured in relationship to the amount of B added as a sintering aid. It was shown that at least 0.2wt%B is required to give an i m p r o v e m e n t in sinterability. T h e r m a l expansion was reduced by an increase in the proportion of cordierite but at the expense of a reduction in strength. CLASSIFICATION O F WC POWDERS FOR P R O D U C T I O N O F HARD ALLOYS
T.B. Gorbacheva, et al, Tsvetn. MetaU, No 3, 1990, 70-74. In Russian. A study was made of the effects of reduction temperatures of WO, and of the carburization temperature to WC, on the morphology, granularity, lattice perfection
and c o m p o s i t i o n of t h e WC p o w d e r s produced. Measurements were m a d e of p a r t i c l e size d i s t r i b u t i o n and specific surface for all stages in the production of WC from WO. The WC lattice was found to have a high degree of perfection. The impurity content of the WC declined with increase in carburization temperature. S I N T E R I N G O F HIGH S P E E D STEEL ( H S S ) POWDER COMPACTS
A.N. Shumilin, et al, (Moscow Inst. of Steel and Alloys, USSR), Izvestia E U.Z Chernaya Metall, No 3, 1990, 102-103. In Russian. A comparison is made of water and gas atomized HSS powders with respect to the production of sintered materials. Differences in compacting pressures were noted. Water atomized powders were said to have an advantage although coated with an oxide layer which must be reduced during sintering. The kinetics of the reduction were also studied. CUTTING P E R F O R M A N C E O F PM HIGH S P E E D STEELS ( H S S )
L. Zima, Strojfr. Vyroba, Vol 37, No 12, 1989, 45-48. In Czech. A study of the cutting performance of HSS is described. The effects of variables in p r e s s i n g a n d s i n t e r i n g on s t r u c t u r e , properties and cutting were investigated. PM high speed steels (HSS) were found to be comparable in efficiency with HSS made by melting and casting. In the case of face milling, PM HSS c o m p a r e d well w i t h cemented carbides. A S P E C T OF T H E P R O D U C T I O N OF F I N I S H E D P R O D U C T S MADE FROM HIGH S P E E D STEEL ( H S S ) POWDER
K-D. Lietzmann, et al, (Bergakademie, Frieberg, Germany), Neue HO:tte, Vol 35, No 7, 255-262. In German. A study was made of gas and water atomized high speed steel (HSS) powders and it is reported that the water atomized powders are rougher than the gas atomized. On pressing of the gas atomized powders there was greater movement of the powder in the die and this led to a greater incidence of cracking. D e n s i f i c a t i o n of t h e two powders was compared and it is suggested that in the case of the water atomized powders optimum densification is obtained by a combination of forging and rolling.
Intermetallic Materials rrH,III
H
II
MODELLING O F HIP CONSOLIDATION O F Ni A L U M I N I D E POWDERS
P~N. Wright, et al, (E.G. & G, Idaho Inc. Idaho Falls, USA), Powder Metallurgy, Vol 33, No 3, 1990, 253-259.
A model has been constructed for the HIP consolidation of Ni3A1 powders. The additive effects of plastic flow, power law creep, boundary diffusion and NabarroHerring and Goble creep are taken into account. HIP maps have been derived which d e s c r i b e t h e HIP c o n s o l i d a t i o n w i t h reasonable accuracy compared with experimental results. Finite element analysis was used as an extension to the HIP map approach.
P R O D U C T I O N OF N | T i SHAPE MEMORY ALLOYS ( S M A ) BY C O M B U S T I O N SYNTHESIS
M. Otaguchi, et al, (National Research Inst. for Metals, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 2, 1990, 214-223. In Japanese. The use of PM to produce NiTi shape memory alloys (SMA) with the objective of attaining closer control of composition is described. Small changes in composition result in large changes in SMA temperature. Combustion synthesis was used. The alloy was found to consist of 100% NiTi which could be HIPed to full density. Wire made from the alloy showed a SMA temperature of about IO0°C.
APPLICATION O F C O M B U S T I O N SYNTHESIS TO P R O D U C T I O N OF ZrNi INTERMETALLIC COMPOUND
C. Nashimura, et al, (National Research Inst. for Metals, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 5, 1990, 603-610. In English. ZrNi i n t e r m e t a l l i c c o m p o u n d s were produced by combustion synthesis and the effects of preheat temperature, in the range 25 to 400°C were studied. The product was porous when the preheat temperature was 100°C and was completely fused at 400°C. The products were found to contain ZrNi, ZrgNi11 and Zr2Ni according to composition of the powder mixture and the process conditions.
STRUCTURE AND P R O P E R T I E S OF Ti ALUMINIDE COMPACTS P R O D U C E D BY HOT P R E S S I N G MECHANICALLY ALLOYED POWDER
& Miyazaki, et al, (Sony Ltd, Tokyo, Japan), J. Japan Inst. of Metals, Vol 54, No 11, 1990, 1279-1283. In Japanese. A m i x t u r e c o n t a i n i n g 70at%Ti and 30%A1 were mechanically alloyed (MA) and hot pressed for 1 hour at 900°C. Near full density was attained. It was shown that the compact consisted of TiaAl with a mean grain size of 1.5~m. The alloy had high compressive strength and low ductility. Recrystallization and grain r e f i n e m e n t occurred during hot working at 900°C.
MPR May 1991 75