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Compaction of powders— spherical magnesium particles
structures and permits investigation of sintering behaviour, permeability a n d separation capacity of sintered materials. Investiptions of process parameters were described.
~ MBLTING I N E w r GAS ATOMIYATION FOE M D U C T I O N OF INTBItMMTALLIC TITANIUM BASED ALLOY POWDEES R. Gerling, (GKSS-Forschungszentrum, Germany). Apparatus for PIGA of TI aluminide powders was described. E l e m e n t a l materials were melted and He or Ar were the inert gases used. It was shown that melting temperature up to 2300°C could be attained and t h a t there was minimal contamination of the melt or powders. The powders had a high degree of homogeneity, small grains and a high proportion of fine powder below 45 pau. Details of the process and operating conditions were outlined.
EFFECTS OF SECOND AGING TREATMENT ON MECHANICAL PROPERTIES OF TUNGSTEN HEAVY
Z. Baosheng et al, (General Research Inst for Non-Ferrous Metals, China). A study of the effects of deformation and heat treatment on the properties of W4%Ni-3~Fe heavy alioywas d e s c f l M It was reported that rolling and aging at 300 to 1100°C i m p r o v e d the m e c h a n i c a l properties. After aging at 500°C the tensile strength and Rockwell C hardness were 1520 MPa and 47 respectively. The increases were attributed to strengthening of the W/matrix interfaces.
LASER~ENINGOF SINTERBDfflYELS
PI~JWEDAND
A.C. Tsyior, (ICM/Krebsoge, Troy, Michigan,
USA). Laser hardening of steels, with regard to the effects of density, was described. The laser Imrdened steels were compared with steels which had been heat treated by a sealed quench technique in respect of structure and properties. The advantages and disadvantases of laser hardening were d~scussed. A production application was discussed.
INFLUENCE OF M D I E ROTATIONS ONMA~NETIC PROPE]tTI~OFPM~ O. P r e ~ and M. S o b ~ (Rotopress Int Inc, Canada). Die pressin~ with rotation of the upper die was discuesed with regard to the type of
motion, circular, ~ ~ s o l n d and
the
or linear
on
investigated. Some studies of soft PM magnetic materials were shown. Improvements in magnetic properties were reported compared with conventionally pressed alloy&
PWrffmdahD~~M
incomplete reduction leads to inferior properties due to the presence of grain boundary oxides in the microstructure. Specimens sintered in H for 90 minutes at 1500°C and heat treated for 60 minutes in N at 1000°C attained 967 MP~ tensile strength with 20.4% elongation. EFFECT OF MICff~(~qgUCTUI~ ON M E H A M C A L RELIABILITY OF SINTBmCn STEELS
I IIIIIIIIIII IIIII
SHEAR LOCALIZATION IN TUNGSTEN HEAW ALLOYS ~. Bose st al, (South Western Research In.st, USA). The properties of W heavy alloys (WHA) and depleted U (DU), when used in military p r o j e c t i l e s , were c o m p a r e d . It was postulated that the superior performance of DU was due to its ability to self sharpen during penetration of armour by localized adiabatic shear and formation of shear bands. Tests on WHA in high strain rate conditions were described. It was reported that localized shear occurred in less than fully dense alloys with inhomogeneous m i c r o s t r u c t u r e s and in W-6%Ni-3%Co which contained precipitates of W and exhibited adiabatic shear induced cracks. It was deduced that the capacity for shear l o c a l i z a t i o n c o u l d be a t t r i b u t e d to microstructural inhomogeneities.
WEAR MODEL OF CEMENTED NONTUNGSTEN CARBIDE COMPOSITES L. Valdma and T. Talving, (Tallinn Technical University, Estonia). Differences in abrasive wear behaviour of coarse and fine grained non-W cemented carbides were attributed to U'anscarbtde fracture in the coarse grain materials and intercarbide fracture in the fine. This model was reported to allow prediction of wear damage and estimation of wear resistance. Experimental studies were described and data presented for CrsC2-Ni and TIC-steel alloys. It was shown that TIC-steel cermets were competitive with WC.Co u n d e r comparable conditions.
EFFECTS OF SINTERING CONDrMONS AND HIghT TREATMENT ON PROPERTIES OF SINTERED TUNGSTEN-MOLYBDENUM-MCKELIRON ALLOYS T. Kohno and N. Yamagishi, (Mitsubishi Materials Corp, Kitami City, Japan). An investigation into the effects of sintering and heat treatment conditions on the mechanical properties of W-4~Mo4%Ni-2%Fe was described. The importance of complete reduction was emphasized as
G. Straffelin st al, (University of Trento, mdy). T h e r e l a t i o n s h i p of m e c h a n i c a l properties, resilience, elongation a n d fracture behavtour to porosity of sintered steels was discussed with reference to the need for a pammeteT to indicate whether a material has a reliable microstructure. Use of a Weibull modulus for this was proposed. Statistical anah~is of a range of porous steels was described and it was shown that the mechanical reliability was related to microstructure. A general criterion for reliabiL~ of sintered steel for structural applications was suggeste~ MECHANICALLY ALLOYED DISP~I~)N ~GTHENED COPPER ALLOYS K.K Anderson and J. Groza, (University of California at Davis, USA). The role of MA in the production of dispersion strengthened Cu alloys was discussed with reference to thermodynamic stability and chemical compatibility of second phase particles and their ability to promote strengthening by dislocation interactions. The impommce of particle size and their ability to undergo controlled growth was emphasized. The applicability of MA to produce ceramic particle reinforced Cu materials was discussed. GROWI'll OF ~ M A N ~ ~ N
IN MNTERED STEEL
I.M.V. C a m i n h a and F.C.R. Assuncao, (National Inst of Technology, Brazil). The use of pure Fe and high-carbon ferro-mansanese powders to produce Fe6%Mn-0.52~C was described. The effects of liquid phase sintering on homogenization a n d m l c r o s t r u c t u r a l evolution d u r i n g processing at 1160°C were outlined. Continuous cooling transformation diagrams were used in the discussion of the structure observed in the steels, pearllte, martensite and balnite. It was noted that the volume fraction of pearllte was reduced by increased heat treatment time a n d this was a t t r i b u t e d to Mn distribution in the austenite. Dflatometry, optical and electron microscopy were used in the study.
MPR November 1992 53
~ MBLTING I N E w r GAS ATOMIYATION FOE M D U C T I O N OF INTBItMMTALLIC TITANIUM BASED ALLOY POWDEES R. Gerling, (GKSS-Forschungszentrum, Germany). Apparatus for PIGA of TI aluminide powders was described. E l e m e n t a l materials were melted and He or Ar were the inert gases used. It was shown that melting temperature up to 2300°C could be attained and t h a t there was minimal contamination of the melt or powders. The powders had a high degree of homogeneity, small grains and a high proportion of fine powder below 45 pau. Details of the process and operating conditions were outlined.
EFFECTS OF SECOND AGING TREATMENT ON MECHANICAL PROPERTIES OF TUNGSTEN HEAVY
Z. Baosheng et al, (General Research Inst for Non-Ferrous Metals, China). A study of the effects of deformation and heat treatment on the properties of W4%Ni-3~Fe heavy alioywas d e s c f l M It was reported that rolling and aging at 300 to 1100°C i m p r o v e d the m e c h a n i c a l properties. After aging at 500°C the tensile strength and Rockwell C hardness were 1520 MPa and 47 respectively. The increases were attributed to strengthening of the W/matrix interfaces.
LASER~ENINGOF SINTERBDfflYELS
PI~JWEDAND
A.C. Tsyior, (ICM/Krebsoge, Troy, Michigan,
USA). Laser hardening of steels, with regard to the effects of density, was described. The laser Imrdened steels were compared with steels which had been heat treated by a sealed quench technique in respect of structure and properties. The advantages and disadvantases of laser hardening were d~scussed. A production application was discussed.
INFLUENCE OF M D I E ROTATIONS ONMA~NETIC PROPE]tTI~OFPM~ O. P r e ~ and M. S o b ~ (Rotopress Int Inc, Canada). Die pressin~ with rotation of the upper die was discuesed with regard to the type of
motion, circular, ~ ~ s o l n d and
the
or linear
on
investigated. Some studies of soft PM magnetic materials were shown. Improvements in magnetic properties were reported compared with conventionally pressed alloy&
PWrffmdahD~~M
incomplete reduction leads to inferior properties due to the presence of grain boundary oxides in the microstructure. Specimens sintered in H for 90 minutes at 1500°C and heat treated for 60 minutes in N at 1000°C attained 967 MP~ tensile strength with 20.4% elongation. EFFECT OF MICff~(~qgUCTUI~ ON M E H A M C A L RELIABILITY OF SINTBmCn STEELS
I IIIIIIIIIII IIIII
SHEAR LOCALIZATION IN TUNGSTEN HEAW ALLOYS ~. Bose st al, (South Western Research In.st, USA). The properties of W heavy alloys (WHA) and depleted U (DU), when used in military p r o j e c t i l e s , were c o m p a r e d . It was postulated that the superior performance of DU was due to its ability to self sharpen during penetration of armour by localized adiabatic shear and formation of shear bands. Tests on WHA in high strain rate conditions were described. It was reported that localized shear occurred in less than fully dense alloys with inhomogeneous m i c r o s t r u c t u r e s and in W-6%Ni-3%Co which contained precipitates of W and exhibited adiabatic shear induced cracks. It was deduced that the capacity for shear l o c a l i z a t i o n c o u l d be a t t r i b u t e d to microstructural inhomogeneities.
WEAR MODEL OF CEMENTED NONTUNGSTEN CARBIDE COMPOSITES L. Valdma and T. Talving, (Tallinn Technical University, Estonia). Differences in abrasive wear behaviour of coarse and fine grained non-W cemented carbides were attributed to U'anscarbtde fracture in the coarse grain materials and intercarbide fracture in the fine. This model was reported to allow prediction of wear damage and estimation of wear resistance. Experimental studies were described and data presented for CrsC2-Ni and TIC-steel alloys. It was shown that TIC-steel cermets were competitive with WC.Co u n d e r comparable conditions.
EFFECTS OF SINTERING CONDrMONS AND HIghT TREATMENT ON PROPERTIES OF SINTERED TUNGSTEN-MOLYBDENUM-MCKELIRON ALLOYS T. Kohno and N. Yamagishi, (Mitsubishi Materials Corp, Kitami City, Japan). An investigation into the effects of sintering and heat treatment conditions on the mechanical properties of W-4~Mo4%Ni-2%Fe was described. The importance of complete reduction was emphasized as
G. Straffelin st al, (University of Trento, mdy). T h e r e l a t i o n s h i p of m e c h a n i c a l properties, resilience, elongation a n d fracture behavtour to porosity of sintered steels was discussed with reference to the need for a pammeteT to indicate whether a material has a reliable microstructure. Use of a Weibull modulus for this was proposed. Statistical anah~is of a range of porous steels was described and it was shown that the mechanical reliability was related to microstructure. A general criterion for reliabiL~ of sintered steel for structural applications was suggeste~ MECHANICALLY ALLOYED DISP~I~)N ~GTHENED COPPER ALLOYS K.K Anderson and J. Groza, (University of California at Davis, USA). The role of MA in the production of dispersion strengthened Cu alloys was discussed with reference to thermodynamic stability and chemical compatibility of second phase particles and their ability to promote strengthening by dislocation interactions. The impommce of particle size and their ability to undergo controlled growth was emphasized. The applicability of MA to produce ceramic particle reinforced Cu materials was discussed. GROWI'll OF ~ M A N ~ ~ N
IN MNTERED STEEL
I.M.V. C a m i n h a and F.C.R. Assuncao, (National Inst of Technology, Brazil). The use of pure Fe and high-carbon ferro-mansanese powders to produce Fe6%Mn-0.52~C was described. The effects of liquid phase sintering on homogenization a n d m l c r o s t r u c t u r a l evolution d u r i n g processing at 1160°C were outlined. Continuous cooling transformation diagrams were used in the discussion of the structure observed in the steels, pearllte, martensite and balnite. It was noted that the volume fraction of pearllte was reduced by increased heat treatment time a n d this was a t t r i b u t e d to Mn distribution in the austenite. Dflatometry, optical and electron microscopy were used in the study.
MPR November 1992 53