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Consolidation of glassy alloy powders in the supercooled liquid state
CONSOLIDATION OF GLASSY ALLOY POWDERS IN THE SUPERCOOLED LIQUID STATE Y.Kawamura et al. (Tohoku University, Sendai, Japan.) Consolidation of glassy :Zr-lOat%hllO%Ni-15%Cu powders by a novel process was described. It was reported that the mechanical properties were identical with those of bulk. alloys. The alloys were warm extruded in the supercooled liquid state just above the glass transition temperature. Tensile strength and Young’s modulus were 1520 MPa and 80 GPa respectively, identical to cast and melt spun materials
Consolidation INNOVATIVE APPROACH TO FABRICATION OF FULLY DENSE, NEAR NET SHAPE PARTS R.V.Raman et al. (Ceracon Inc. USA.) It was reported that a shaping process (gel-casting) had been combined with pseudo-HIP (the Ceracon process) to prepare fully dense, near net shape parts. The effect of pseudo-HIP on densification of gel-cast Al powders was described. Gel cast and densified materials were characterized and results presented. Future implications were outlined. DENSIFJCATION OF TOOL STEEL POWDERS AT HIGH TEMPERATURES K.Kim et al. (Pohang IJniversity of Science and Techncdogy, Pohang, Korea.) Various methods of densification of tool steel powders were investigated. Pressureless sintering gave full density at controlled temperature near the solidus. Finite element calculations were compared wit,h experiment. The shielding effect of containers in HIP was considered. There was good agreement between calculation and experiment for HIP but not for uniaxial compression.
Laser manufacturing PM LASER MANUFACTURING TITANIUM STRUCTURES’
OF
E.J.Whitney et al. (Pennsylvania State University, USA.) A fluidized bed laser manufacturing process for Ti alloy parts was described. A 14 kW CO2 laser irradiated a section of the powder part, which fused. The powder bed is fluidized to add more powder to the part which is further irradiated. Thus, the part gradually builds up. Materials with high density were produced with minimum contamination.
Commercial development to be in progress.
was reported
LASER METAL DEPOSITION OF SUPERALLOY 625 FOR FREE FORM FABRICATION D.M.Keicher rt al. (Sandia National Laboratory, USA.) Investigations aimed at demonstrating the feasibility of preparing a near net shape part in a Ni base superalloy were described. The technique used laser deposited alloy powder and attained high density. It was shown that grain growth occurred across the deposited alloy. The process was monitored by high speed and infrared imaging. It was shown that powder size range affected stability and thus performance of the deposition process. Alloy composition was not degraded.
was described. The advantages of using HIP were said to be low cost, minimum welding and isotropy of mechanical properties.
DEVELOPMENT OF STAINLESS STEEL-COPPER NEAR NET SHAPE PARTS BY HIP FOR ROCKET APPLICATIONS
G.O.Rhodes. (Crucible Research Inc, USA.) The production of a complex part for a rocket combustion chamber. using PM and HIP, was described. Near net shape stainless steel and copper alloy subparts were made from Ar atomized powders. Ceramic moulds and selectively laser sintered polycarbonate patterns were used. Aspects of processing and materials properties were reviewed.
Composite materials FIFTH INTERNATIONAL CONFERENCE ON ADVANCED PARTICULATE MATERIALS AND PROCESSES. The following Abstracts are from papers presented at the Conference, which was held in Palm Beach, Florida, USA, in April 1997. I-
Steels LOW ACTIVATION OXIDE DISPERSION STRENGTHENED FERRITIC STEELS FOR FUSION REACTORS FHFroes et al. (University of Idaho. Moscow, Idaho, USA.) It was reported that a range of ferritic stainless steels, Fe-(5. 9, 11, 13 and 13.5)wt’~,Cr-2%W-0.5%Ti-O,25’~~,Y~O~~ had been prepared by mechanical alloping. Only the 13.5’XCr alloy did not show any transformation to austenite and these powders were consolidated by HIP and swaging. The swaged alloy contained elongated grains and had a Rockwell hardness of 65C. Only a small reduction in hardness was found on heating up to 1200°C. suggesting high thermal stability. The alloy was reported to be superior to some similar annealed allovs. CLAD-WATER COOLED COMPONENTS BY HIP-PM TECHNOLOGY C.G.Hjorth et al. (Powdermet Sweden AB, Surahammer. Sweden.) The objective of the work described was to show the capability of HIP for fabrication of a copper-clad, watercooled, fusion reactor component. The base alloy was 316L stainless steel. The part has an array of water cooling channels. The fabrication of the 2 tonne part
STRUCTURAL ANALYSIS AND COMPARISON OF PM AND MECHANICALLY ALLOYED TUNGSTEN BASE MATERIALS C.Kennedy et al. (University of Texas. USA.) W heavy alloys and depleted U0.75’XTi alloys were discussed with regard to deformation behaviour on impact loading and application as kinet ic energy penetrators. -4 study of mechanically alloyed and PM processed W-(1, 2 or 5)vol% HfC, with and without 0.5%Ir, for possible use as penetrators. was described. Optical and electron microscopy were used to characterize structure. A low dislocation density and high Vicker’s hardness, 700 to 1200. were reported. Effects of milling time on final hardness were described. MANUFACTURE UD PROPERTIES OF COPPER ALLOYS DISPERSION STRENGTHENED WITH TITANIUM CARBIDE
Of C.Sauer et al. (Dresden University Technology, Dresden, Germany.) It was noted that dispersion strengthened Cu alloys can have high thermal conductivity and high temperature strength. An investigation of MA of elemental Cu.Ti-C powders. to synthesize TiC in situ was described. TiC dispersoids. 10 to 50 nm in size and locwlized on grain boundaries had been made, the matrix being microcrystalline with a grain size of 100 to 300 nm. Creep properties of consolidated materials with 3 to IOvol%TiC were determined. The alloys had Vickers hardness of 3 15. tensile strength of 1100 MPa, 10% elongation and BO%IACS electrical conductivity at ambient temperatures.
MPR January 1998 39
Consolidation INNOVATIVE APPROACH TO FABRICATION OF FULLY DENSE, NEAR NET SHAPE PARTS R.V.Raman et al. (Ceracon Inc. USA.) It was reported that a shaping process (gel-casting) had been combined with pseudo-HIP (the Ceracon process) to prepare fully dense, near net shape parts. The effect of pseudo-HIP on densification of gel-cast Al powders was described. Gel cast and densified materials were characterized and results presented. Future implications were outlined. DENSIFJCATION OF TOOL STEEL POWDERS AT HIGH TEMPERATURES K.Kim et al. (Pohang IJniversity of Science and Techncdogy, Pohang, Korea.) Various methods of densification of tool steel powders were investigated. Pressureless sintering gave full density at controlled temperature near the solidus. Finite element calculations were compared wit,h experiment. The shielding effect of containers in HIP was considered. There was good agreement between calculation and experiment for HIP but not for uniaxial compression.
Laser manufacturing PM LASER MANUFACTURING TITANIUM STRUCTURES’
OF
E.J.Whitney et al. (Pennsylvania State University, USA.) A fluidized bed laser manufacturing process for Ti alloy parts was described. A 14 kW CO2 laser irradiated a section of the powder part, which fused. The powder bed is fluidized to add more powder to the part which is further irradiated. Thus, the part gradually builds up. Materials with high density were produced with minimum contamination.
Commercial development to be in progress.
was reported
LASER METAL DEPOSITION OF SUPERALLOY 625 FOR FREE FORM FABRICATION D.M.Keicher rt al. (Sandia National Laboratory, USA.) Investigations aimed at demonstrating the feasibility of preparing a near net shape part in a Ni base superalloy were described. The technique used laser deposited alloy powder and attained high density. It was shown that grain growth occurred across the deposited alloy. The process was monitored by high speed and infrared imaging. It was shown that powder size range affected stability and thus performance of the deposition process. Alloy composition was not degraded.
was described. The advantages of using HIP were said to be low cost, minimum welding and isotropy of mechanical properties.
DEVELOPMENT OF STAINLESS STEEL-COPPER NEAR NET SHAPE PARTS BY HIP FOR ROCKET APPLICATIONS
G.O.Rhodes. (Crucible Research Inc, USA.) The production of a complex part for a rocket combustion chamber. using PM and HIP, was described. Near net shape stainless steel and copper alloy subparts were made from Ar atomized powders. Ceramic moulds and selectively laser sintered polycarbonate patterns were used. Aspects of processing and materials properties were reviewed.
Composite materials FIFTH INTERNATIONAL CONFERENCE ON ADVANCED PARTICULATE MATERIALS AND PROCESSES. The following Abstracts are from papers presented at the Conference, which was held in Palm Beach, Florida, USA, in April 1997. I-
Steels LOW ACTIVATION OXIDE DISPERSION STRENGTHENED FERRITIC STEELS FOR FUSION REACTORS FHFroes et al. (University of Idaho. Moscow, Idaho, USA.) It was reported that a range of ferritic stainless steels, Fe-(5. 9, 11, 13 and 13.5)wt’~,Cr-2%W-0.5%Ti-O,25’~~,Y~O~~ had been prepared by mechanical alloping. Only the 13.5’XCr alloy did not show any transformation to austenite and these powders were consolidated by HIP and swaging. The swaged alloy contained elongated grains and had a Rockwell hardness of 65C. Only a small reduction in hardness was found on heating up to 1200°C. suggesting high thermal stability. The alloy was reported to be superior to some similar annealed allovs. CLAD-WATER COOLED COMPONENTS BY HIP-PM TECHNOLOGY C.G.Hjorth et al. (Powdermet Sweden AB, Surahammer. Sweden.) The objective of the work described was to show the capability of HIP for fabrication of a copper-clad, watercooled, fusion reactor component. The base alloy was 316L stainless steel. The part has an array of water cooling channels. The fabrication of the 2 tonne part
STRUCTURAL ANALYSIS AND COMPARISON OF PM AND MECHANICALLY ALLOYED TUNGSTEN BASE MATERIALS C.Kennedy et al. (University of Texas. USA.) W heavy alloys and depleted U0.75’XTi alloys were discussed with regard to deformation behaviour on impact loading and application as kinet ic energy penetrators. -4 study of mechanically alloyed and PM processed W-(1, 2 or 5)vol% HfC, with and without 0.5%Ir, for possible use as penetrators. was described. Optical and electron microscopy were used to characterize structure. A low dislocation density and high Vicker’s hardness, 700 to 1200. were reported. Effects of milling time on final hardness were described. MANUFACTURE UD PROPERTIES OF COPPER ALLOYS DISPERSION STRENGTHENED WITH TITANIUM CARBIDE
Of C.Sauer et al. (Dresden University Technology, Dresden, Germany.) It was noted that dispersion strengthened Cu alloys can have high thermal conductivity and high temperature strength. An investigation of MA of elemental Cu.Ti-C powders. to synthesize TiC in situ was described. TiC dispersoids. 10 to 50 nm in size and locwlized on grain boundaries had been made, the matrix being microcrystalline with a grain size of 100 to 300 nm. Creep properties of consolidated materials with 3 to IOvol%TiC were determined. The alloys had Vickers hardness of 3 15. tensile strength of 1100 MPa, 10% elongation and BO%IACS electrical conductivity at ambient temperatures.
MPR January 1998 39