- Email: [email protected]
Microstructural assessment of tungsten heavy alloys
SINTERING OF ALUMINIUM AT HIGH PRESSURE
NITRIDE
V.B. Shapilo et al, Poroshkovaya Metallurgiya, No 8, 1993, 62-65. (In Russian). Sintering of AlN at 5 GPa pressure and 1650, 1750, 1850 and 1950°C was investigated. It is reported that the sintering is underlain by plastic strain requiring post deformation heat treatment.
htermetallic FORMATION ALUMJNIDE ELECTRICAL
FROM BY HIP
H.A. Maupin, J.C. Rawers (US Bureau of Mines, USA), J. Materials Science, Letters, Vol 12, No 3, 1993, 165-167. Investigations of the formation of TiAl during HIP of elemental powders are described. An attempt was made to use higher than usual HIP pressures and it is reported that a composite Ti/TiAl material was made. It is recommended that high HIP pressure should not be applied until the synthesis of TiAl is completed for a fully dense near net shape material consisting of TiAl only to be obtained. Addition of B, C, or Si did not give additional phases but Fe band Ni formed additional aluminides.
PMaTEC’94 The abstracts which follow are of papers which were presented at the International Conference on Powder Metallurgy and Particulate Materials which was held in Toronto, Canada, from 8th to 11th May 1994. I
Tungsten alloys EVALUATION OF CRACK INITIATION AND PROPAGATION ENERGIES OF TUNGSTEN
RAPID TRIBOLOGICAL
and
DATA
GENERATION FOR PM MATERIALS USING MAPPING TECHNIQUE AND
COATING
OF TOOL STEELS
W.Z. Misiolek et al (Rensselaer Polytechnic Inst., Troy, New York, USA) The use of ceramic coatings to improve the performance of cutting tool materials was discussed with reference to the adhesion of the coating, application by thermal spraying and thickness uniformity. An investigation in which alumina was deposited in H13 tool steel by inert gas thermal spraying was described. Intermediate binder layers of Ni aluminides were studied, effects of thermal expansion being considered. OPTIMIZATION
OF COMPOSITION
OF
NITROGEN-HYDROGEN SINTERING ATMOSPHERES FOR STEEL
ALLOYS
G.T. Gray et al (Los Alamos National Laboratory, USA) An investigation of the mechanical properties of W-B%Ni-2%Fe and W-S%Nil%Co was described the objective being to compare the fracture behaviour of the two alloys and to identify the connection between fracture and ballistic performance. Differences were detected in crack initiation and propagation energies at higher loading rates, the Co alloy being tougher. Fracture by cleavage was found in the W grains and shear in the matrix. MICROSTRUCTURAL ASSESSMENT TUNGSTEN HEAVY ALLOYS
UK) The limited availability of wear data for sintered materials was discussed with regard to the difficulty of using it for design. A display “wear atlas”, which presents data from laboratory tests in a manner which allows a designer to decide which are the most important factors in his was described. Data for application, different combinations of materials can be rapidly determined. Illustrations were given to show the effects of surface treatments on plain Fe, NC100.24, parts with different counterbodies. Examples were given to show the usefulness of the technique. ALUMINA
OF
RJ. Dowding, K.F. Ryan (U.S. Army Research Laboratories, USA) The testing of alloys for microstructure and properties was reviewed with reference to models which can be applied to thermomechanical working. A study of
and Si were found to accelerate the reduction reaction and to improve the surface quality. The total oxide film thickness was reduced from 12 nm to 7 nm. EVALUATION OF PM TOOL STEELS FOR BEARING APPLICATIONS
T.S. Eyre et al (Brunel University, Uxbridge,
OF TITANIUM POWDERS
Surface modification tribology
ATLAS
materials
COMPOSITES
alloys with 91 to 97%W was described. Microstructures observed were described and their significance discussed.
D. Garg et al (Air Products and Chemicals Inc., Allentown, Pennsylvania, USA) The use of N-H atmospheres in the sintering of steel was discussed with reference to the advantages and disadvantages. In particular surface decarburization was considered. The composition of N-H optimum atmospheres, for attainment of good quality and strength with out loss of surface hardness, was described. SURFACE ANALYSIS OF WATER ATOMIZED AUSTENITIC STEEL POWDERS Y. Dong et al (University of Science and Technology, Beijing, China) An investigation of the composition of the oxide film on water atomized 304L stainless steel powder was described. It was reported that the film consists of mixed Fe, Mn, Cr and Si oxides with C. Additions of Al
P.K. Pearson et al (The Torrington Co, Torrington, Connecticut, USA) An investigation of the rolling contact fatigue properties of selected steels was described. PM steels produced from gas atomized powders were compared with vacuum induction melted materials and the properties of the PM and VIM steels were reported to be comparable. Effects of 0 content, mechanical properties and alloy carbide size on rolling contact fatigue were discussed.
Metal injection moulding INJECTION
MOULDING
OF TUNGSTEN
HEAVY ALLOY PENETRATORS
K.F. Hens, R.M. German (Pennsylvania State University, Pennsylvania, USA) The application of injection moulding in the production of W heavy alloy penetrators was discussed. From test results it was deduced that process optimization is required to attain tensile strengths of 1.1 GPa. This is considered to require tailored binders, debinding procedures and powders which are suitable for moulding at high solids loading in the feedstock to give good mechanical uniform shrinkage, and properties, microstructures. It was reported that processing had been modified to these ends. MAGNETIC INJECTION
CHARACTERISTICS OF MOULDED IRON BASE
SOFT MAGNETIC
ALLOYS
Y.G. Chang, N.E. Farb (Printronix Inc, USA)
An investigation of the use of MIM for production of Fe-Co and Fe-Co-V soft magnetic alloys was described and magnetic properties of toroidal specimens of Fe-36%Co and Fe-49%Co-2%V were determined and compared with wrought alloys. It was shown that MIM parts can be produced to near net shape with high saturation induction and low coercivity. PILOT
PRODUCTION
PACKAGES MOULDING
OF ELECTRONIC
BY POWDER
INJECTION
R.M. German et al (Pennsylvania State University, Pennsylvania, USA) The need for heat sinks/packages for microelectronic devices was discussed. Injection moulding was used to fabricate a number of parts such as heat dissipators and packaging with thermal conductivlties in excess of 200 W/mK. The importance of powder selection and control and process control with advanced techniques, in order
MPR January 1995 43
NITRIDE
V.B. Shapilo et al, Poroshkovaya Metallurgiya, No 8, 1993, 62-65. (In Russian). Sintering of AlN at 5 GPa pressure and 1650, 1750, 1850 and 1950°C was investigated. It is reported that the sintering is underlain by plastic strain requiring post deformation heat treatment.
htermetallic FORMATION ALUMJNIDE ELECTRICAL
FROM BY HIP
H.A. Maupin, J.C. Rawers (US Bureau of Mines, USA), J. Materials Science, Letters, Vol 12, No 3, 1993, 165-167. Investigations of the formation of TiAl during HIP of elemental powders are described. An attempt was made to use higher than usual HIP pressures and it is reported that a composite Ti/TiAl material was made. It is recommended that high HIP pressure should not be applied until the synthesis of TiAl is completed for a fully dense near net shape material consisting of TiAl only to be obtained. Addition of B, C, or Si did not give additional phases but Fe band Ni formed additional aluminides.
PMaTEC’94 The abstracts which follow are of papers which were presented at the International Conference on Powder Metallurgy and Particulate Materials which was held in Toronto, Canada, from 8th to 11th May 1994. I
Tungsten alloys EVALUATION OF CRACK INITIATION AND PROPAGATION ENERGIES OF TUNGSTEN
RAPID TRIBOLOGICAL
and
DATA
GENERATION FOR PM MATERIALS USING MAPPING TECHNIQUE AND
COATING
OF TOOL STEELS
W.Z. Misiolek et al (Rensselaer Polytechnic Inst., Troy, New York, USA) The use of ceramic coatings to improve the performance of cutting tool materials was discussed with reference to the adhesion of the coating, application by thermal spraying and thickness uniformity. An investigation in which alumina was deposited in H13 tool steel by inert gas thermal spraying was described. Intermediate binder layers of Ni aluminides were studied, effects of thermal expansion being considered. OPTIMIZATION
OF COMPOSITION
OF
NITROGEN-HYDROGEN SINTERING ATMOSPHERES FOR STEEL
ALLOYS
G.T. Gray et al (Los Alamos National Laboratory, USA) An investigation of the mechanical properties of W-B%Ni-2%Fe and W-S%Nil%Co was described the objective being to compare the fracture behaviour of the two alloys and to identify the connection between fracture and ballistic performance. Differences were detected in crack initiation and propagation energies at higher loading rates, the Co alloy being tougher. Fracture by cleavage was found in the W grains and shear in the matrix. MICROSTRUCTURAL ASSESSMENT TUNGSTEN HEAVY ALLOYS
UK) The limited availability of wear data for sintered materials was discussed with regard to the difficulty of using it for design. A display “wear atlas”, which presents data from laboratory tests in a manner which allows a designer to decide which are the most important factors in his was described. Data for application, different combinations of materials can be rapidly determined. Illustrations were given to show the effects of surface treatments on plain Fe, NC100.24, parts with different counterbodies. Examples were given to show the usefulness of the technique. ALUMINA
OF
RJ. Dowding, K.F. Ryan (U.S. Army Research Laboratories, USA) The testing of alloys for microstructure and properties was reviewed with reference to models which can be applied to thermomechanical working. A study of
and Si were found to accelerate the reduction reaction and to improve the surface quality. The total oxide film thickness was reduced from 12 nm to 7 nm. EVALUATION OF PM TOOL STEELS FOR BEARING APPLICATIONS
T.S. Eyre et al (Brunel University, Uxbridge,
OF TITANIUM POWDERS
Surface modification tribology
ATLAS
materials
COMPOSITES
alloys with 91 to 97%W was described. Microstructures observed were described and their significance discussed.
D. Garg et al (Air Products and Chemicals Inc., Allentown, Pennsylvania, USA) The use of N-H atmospheres in the sintering of steel was discussed with reference to the advantages and disadvantages. In particular surface decarburization was considered. The composition of N-H optimum atmospheres, for attainment of good quality and strength with out loss of surface hardness, was described. SURFACE ANALYSIS OF WATER ATOMIZED AUSTENITIC STEEL POWDERS Y. Dong et al (University of Science and Technology, Beijing, China) An investigation of the composition of the oxide film on water atomized 304L stainless steel powder was described. It was reported that the film consists of mixed Fe, Mn, Cr and Si oxides with C. Additions of Al
P.K. Pearson et al (The Torrington Co, Torrington, Connecticut, USA) An investigation of the rolling contact fatigue properties of selected steels was described. PM steels produced from gas atomized powders were compared with vacuum induction melted materials and the properties of the PM and VIM steels were reported to be comparable. Effects of 0 content, mechanical properties and alloy carbide size on rolling contact fatigue were discussed.
Metal injection moulding INJECTION
MOULDING
OF TUNGSTEN
HEAVY ALLOY PENETRATORS
K.F. Hens, R.M. German (Pennsylvania State University, Pennsylvania, USA) The application of injection moulding in the production of W heavy alloy penetrators was discussed. From test results it was deduced that process optimization is required to attain tensile strengths of 1.1 GPa. This is considered to require tailored binders, debinding procedures and powders which are suitable for moulding at high solids loading in the feedstock to give good mechanical uniform shrinkage, and properties, microstructures. It was reported that processing had been modified to these ends. MAGNETIC INJECTION
CHARACTERISTICS OF MOULDED IRON BASE
SOFT MAGNETIC
ALLOYS
Y.G. Chang, N.E. Farb (Printronix Inc, USA)
An investigation of the use of MIM for production of Fe-Co and Fe-Co-V soft magnetic alloys was described and magnetic properties of toroidal specimens of Fe-36%Co and Fe-49%Co-2%V were determined and compared with wrought alloys. It was shown that MIM parts can be produced to near net shape with high saturation induction and low coercivity. PILOT
PRODUCTION
PACKAGES MOULDING
OF ELECTRONIC
BY POWDER
INJECTION
R.M. German et al (Pennsylvania State University, Pennsylvania, USA) The need for heat sinks/packages for microelectronic devices was discussed. Injection moulding was used to fabricate a number of parts such as heat dissipators and packaging with thermal conductivlties in excess of 200 W/mK. The importance of powder selection and control and process control with advanced techniques, in order
MPR January 1995 43