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Development of PM silicon based alloys
PM'93 The abstracts which follow are of papers which were presented at the 1993. Powder Metallurgy World Congress which was held in Kyoto, Japan, from 12 to 15 July 1993. Self propagating high temperature synthesis SELF PROPAGATING HIGH TEMPERATURE SYNTHESIS IN TITANIUM-CARBON-MOLYBDENUM SYSTEM B.D. Cho, t5D. Hahn, (Korea Institute of Machinery and Metals, Korea). An investigation of SHS in Ti-C-(up to 70 wt%)Mo was described. Ti and C were in equiatomic proportions. Powders were ignited and the kinetics of synthesis was determined. The processed powders were shown to contain TiC and M02C in proportions dependent on composition. The powders were consolidated and the mechanical properties determined. CEMENTED CARBIDES MADE BY SELF PROPAGATING HIGH TEMPERATURE SYNTHESIS-PSEUDO-HIP OF TITANIUM CARBIDE-NICKEL (MOLYBDENUM) Y. Sheng et al (University of Science and Technology, Beijing, China). It was reported that a cemented carbide based on TiC and Ni(Mo) had been produced by SHS-pseudo HIP. Effects of process conditions on density were studied. It was shown that there is an optimum delay time between synthesis and pressing w h i c h is r e l a t e d to outgassing. The s t r u c t u r e s an d p r o p e r t i e s w e r e compared with conventional TiC-(Ni, Mo). Mo was stated to reduce loss of Ni by volatilization. COMBUSTION SYNTHESIS OF IRON ALUMINIDES T. Um, R. Watanagae (Tohoku University, Sendai, Japan). Synthesis of FeA1 by explosive SHS and propagating SHS were investigated. It was shown that a eutectic phase is formed prior to the formation of FeA1. Fine initial mixing of the powders was reported to enhance reaction rates. CEMENTED CARBIDES MADE BY HIGH TEMPERATURE SYNTHESIS AND HOT PRESSING H. Tengzheng et al (Central South Iron and Steel Research Institute, Hunan, China).
It was reported that TiC/Ni and TiC/(Ni, Mo) f u n c t i o n a l l y g r a d i e n t m a t e r i a l s (materials with a composition gradient) had been prepared by SHS followed by hot pressing. The structures were investigated and it was shown that the composition g r a d i e n t was u n i f o r m an d w i t h o u t interfaces. PRODUCTION OF DIAMOND CONTAINING FUNCTIONALLY GRADED MATERIALS BY SHS K.L. Padyukov et al (Centre for SHS, Moscow, Russia). An investigation of the production of functionally gradient materials based on T i C - N i - d i a m o n d was d e s c r i b e d . The structures and properties of the materials were described. Attention was given to the characteristics of the diamond particles before and after processing.
ATOMIZATION PRODUCTION OF ANTIMIONY POWDER BY ATOMIZATION Z. Weicheng, W.Z. Chao (Central Iron and Steel Research Institute, Beijing, China). Production of Sb powder by N gas atomization was reported. The powders w e r e s h o w n t o be s p h e r i c a l or microcrystalline. Variations in particle shape and properties with droplet size, surface tension and droplet mean free path and cooling effects were discussed. FABRICATION AND PROPERTIES OF PM MAGNESIUM-CALCIUM ALLOYS F.M. Knoop et al (Zentrum Ffir Funktionswerkstoffe GmbH, Germany). It was reported that a Mg alloy (QE22) powder with 1,4,7 or 13% Ca had been produced by high pressure gas atomization. Powder structure and properties were described and the effects of processing parameters were discussed. Some improvements in mechanical properties and superplastic behaviour were reported. SURFACE ANALYSIS OF GAS ATOMIZED NICKEL ALLOY POWDER AND PROPERTIES OF COMPACTED ALLOY T. Fukuda et al (Sumitomo Metal Indus-
tries Ltd, Tokyo, Japan). An investigation of rapid solidification of a high Ni alloy was described, use being made of a confined type of gas atomizer with a modified nozzle. Particle sizes were correlated with process variables. Surface analysis showed t h a t t h er e was less Ni(OH)u, Cr203 and Nb2Os than was the case with more slowly cooled powders. Voids w e r e f o u n d in welds. It was r e c o m m e n d e d t h a t r a p i d l y solidified p o w d e r s s h o u l d be u s e d f o r t h e production of high quality PM products. THERMAL HISTORIES OF ATOMIZED AND COMPACTED METALS V. Fritsching et al (Fraunhofer Institute for Materials Science, Bremen, Germany). An advantage, a fine structure of spray forming, used for production of near-net shape preforms and metal m a t r i x composites was discussed. Experimental and numerical results of tests of spray forming were presented. Consideration was given to temperatures and solidification histories of droplets during flight and growth of a stationary circular deposit. CHARACTERIZATION OF GAS ATOMIZED MANGANESE-ALUMINIUMCARBON POWDERS A. Yanagatini et al (Sanyo Special Steel Co Ltd, Japan). The magnetic applications of A1MnC alloys were discussed with regard to the strength and machinability. An e x a m i n a t i o n of gas a t o m i z e d MnAIC powders was reported to show regions high and low in Mn. Two exotherms were noted on heating. It was considered that t h e r e a r e two s t e p s in t h e p h a s e transformation of e to z. DEVELOPMENT OF PM SILICON BASED ALLOYS L. L'Estrade et al (ITEC AB, Sweden). It was reported that by the use of rapid solidification and PM processing Si base structural materials with low density, high stiffness, low thermal expansion, good high t e m p e r a t u r e s t r e n g t h and c o r r o s i o n resistance could be produced. This was attributed to the avoidance of segregation to which cast Si alloys are subject. Process conditions were outlined.
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It was reported that TiC/Ni and TiC/(Ni, Mo) f u n c t i o n a l l y g r a d i e n t m a t e r i a l s (materials with a composition gradient) had been prepared by SHS followed by hot pressing. The structures were investigated and it was shown that the composition g r a d i e n t was u n i f o r m an d w i t h o u t interfaces. PRODUCTION OF DIAMOND CONTAINING FUNCTIONALLY GRADED MATERIALS BY SHS K.L. Padyukov et al (Centre for SHS, Moscow, Russia). An investigation of the production of functionally gradient materials based on T i C - N i - d i a m o n d was d e s c r i b e d . The structures and properties of the materials were described. Attention was given to the characteristics of the diamond particles before and after processing.
ATOMIZATION PRODUCTION OF ANTIMIONY POWDER BY ATOMIZATION Z. Weicheng, W.Z. Chao (Central Iron and Steel Research Institute, Beijing, China). Production of Sb powder by N gas atomization was reported. The powders w e r e s h o w n t o be s p h e r i c a l or microcrystalline. Variations in particle shape and properties with droplet size, surface tension and droplet mean free path and cooling effects were discussed. FABRICATION AND PROPERTIES OF PM MAGNESIUM-CALCIUM ALLOYS F.M. Knoop et al (Zentrum Ffir Funktionswerkstoffe GmbH, Germany). It was reported that a Mg alloy (QE22) powder with 1,4,7 or 13% Ca had been produced by high pressure gas atomization. Powder structure and properties were described and the effects of processing parameters were discussed. Some improvements in mechanical properties and superplastic behaviour were reported. SURFACE ANALYSIS OF GAS ATOMIZED NICKEL ALLOY POWDER AND PROPERTIES OF COMPACTED ALLOY T. Fukuda et al (Sumitomo Metal Indus-
tries Ltd, Tokyo, Japan). An investigation of rapid solidification of a high Ni alloy was described, use being made of a confined type of gas atomizer with a modified nozzle. Particle sizes were correlated with process variables. Surface analysis showed t h a t t h er e was less Ni(OH)u, Cr203 and Nb2Os than was the case with more slowly cooled powders. Voids w e r e f o u n d in welds. It was r e c o m m e n d e d t h a t r a p i d l y solidified p o w d e r s s h o u l d be u s e d f o r t h e production of high quality PM products. THERMAL HISTORIES OF ATOMIZED AND COMPACTED METALS V. Fritsching et al (Fraunhofer Institute for Materials Science, Bremen, Germany). An advantage, a fine structure of spray forming, used for production of near-net shape preforms and metal m a t r i x composites was discussed. Experimental and numerical results of tests of spray forming were presented. Consideration was given to temperatures and solidification histories of droplets during flight and growth of a stationary circular deposit. CHARACTERIZATION OF GAS ATOMIZED MANGANESE-ALUMINIUMCARBON POWDERS A. Yanagatini et al (Sanyo Special Steel Co Ltd, Japan). The magnetic applications of A1MnC alloys were discussed with regard to the strength and machinability. An e x a m i n a t i o n of gas a t o m i z e d MnAIC powders was reported to show regions high and low in Mn. Two exotherms were noted on heating. It was considered that t h e r e a r e two s t e p s in t h e p h a s e transformation of e to z. DEVELOPMENT OF PM SILICON BASED ALLOYS L. L'Estrade et al (ITEC AB, Sweden). It was reported that by the use of rapid solidification and PM processing Si base structural materials with low density, high stiffness, low thermal expansion, good high t e m p e r a t u r e s t r e n g t h and c o r r o s i o n resistance could be produced. This was attributed to the avoidance of segregation to which cast Si alloys are subject. Process conditions were outlined.
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