- Email: [email protected]
Porosity and filtration characteristics of porous filters
reported to grow discontinuously
during
LPS. Inhibition of grain growth microstructures were discussed.
and
PLASMA SINTERING OF ATTRITION MILLED COMPOSITE PRECURSORS
S.H. Kim, S.N. Sinha (University of Illinois, USA). Sintering characteristics of &AlzOs, made from attrition milled powders by plasma sintering were investigated with regard to process conditions. Milling was reported to be able to reduce particle size to 0.33 urn. Sintering at 8 kV gave density above 98%. The microstructure was shown to contain interpenetrating phase composites. Characteristics of powder and compacts were described. The potential of the technique was assessed. DYNAMICS OF MATERLALS PROCESSED
BY VIBRATORY MACHINES
A. Sverdlin et al. (Bradley University, USA). Interdependences between particulate and granular matter and processing machinery were discussed with regard to machine motions and material properties. A vibration/rheological model, to simulate material behavlour, in which interacting forces are considered, was described with reference to machine dynamics. Initial equations are reduced to a set of differential equations which were solved by numerical integration. Application to a vibratory conveyor, a compaction table and mill was outlined. Results were validated by experiment.
EURO follow
PM’95. The abstracts which are of papers which were
presented at the European Conference on Advanced PM Materials which was
held
in
Birmingham,
UK,
in
October 1995.
The paper discussed PM Fe and Cu based friction materials. An investigation in which amounts of additives were kept small was described. The influence of different graphite, Sic and kieselguhr contents were studied. Swelling during sintering was reported. This was attributed to high interface energies between metallic and non-metallic phases. SELF LUBRICATING IRON BASE MATERIALS MADE BY MECHANICAL ALLOYING
POROSITY AND FILTRATION CHARACTERISTICS
OF POROUS
FILTERS
SINTERED
COPPER BASE METAL
COMPOSITES
REINFORCED
WITH STEEL FIBRES
METAL INJECTION TUNGSTEN
MOULDING
OF
HEAVY ALLOYS
F. Petzold et al. (Fraunhofer Inst., Bremen, Germany) Applications of W heavy alloys were outlined. It was reported that complex shaped W heavy alloy parts could be made by MIM. Production of a radiation shield was described.
Structural parts STUDIES
OF GREEN AND SINTERED
IRON AND COPPER BASED FRICTION MATERIALS
C. Simons et al. (Forschungzentrum Jfilich GmbH, Jiilich, Germany).
46
MPR July/August
1996
Superalloys
P. Gheorge, M. Gheorge (ICEM SA, Romania). The sinterability of Cu base MMCs, reinforced with Fe or Cu plated Fe fibres was investigated by electron microscopy. Greater matrix diffusion was reported for the alloy with plated fibres. Mechanical and physical properties were described. MANUFACTURE OF METAL MATRIX COMPOSITES REINFORCED WITH CARBON FIBRE
C. Mircea, C. Novae (METAV SA, Romania). An investigation of Cu base MMCs, reinforced with C fibre, was described. The fibres were dispersed in the metal by a range of methods. Consolidation was by die pressing and solid or pressurized liquid phase sintering. Improved frictional properties were reported.
- PAST PRESENT
AND FUTURE
W.B. Eisen (Crucible Metals Corp, Plttsburg, USA). Application of PM Ni base superalloys as discs in gas turbines was discussed with reference to higher operating temperatures, engine reliability, process control to ensure high part quality and supersolvus heat treatment. Current development of alloys to meet the increased operating temperature requirement was noted. It was predicted that Ni based alloys would continue to find aerospace and ground based gas turbine applications. MODELLING
OF ELEVATED
TEMPERATURE
F.F. Ambrozio, P. Luzinette (Cidade University, Brazil). Methods for the study of filter characteristics were described. Results of measurements on 316L stainless steel were presented for a range of filter discs made from two different powder size distributions and pressed at 100 to 300 MPa. The filters were characterized for density, structure, porosity content, interconnected pores and filtration behaviour assessed by permeability and maximum pore size.
COUPLE
M. Lucaci et al. (METAV SA Romania). Tribological behaviour of a sintered Cu matrix/ceramic composite, in sliding contact with grey cast iron was investigated. Higher coefficients of friction and lower wear rates were reported for the composite materials.
PM SUPERALLOYS
B. Gunther et al. (Fraunhofer Inst., Bremen, Germany). It was reported that high energy ball milling homogeneously distributed graphite and hexagonal BN, up to ZOvol%,in Fe and Fe-Si alloys. Structural evolution, as a function of milling time was investigated. Refined lamellar structures were developed in the powders which were mainly retained on die pressing and sintering. Block-on-ring tests showed that friction diminished with milling time, attributed to structural refinement.
MATRIX
Metal injection moulding
SINTERED FRICTION MATERIALS
DISPERSION
DEFORMATION
OF
STRENGTHENED
SUPERALLOY
U. BBhm et al. (University of ErlangenNtirnberg, Germany). A model, based on Hasen-AlexanderIlschner theory, was used to describe steady state and transient creep deformation of Ni based ODS superalloy MA754 and the equivalent oxide free alloy Nimonic 75. The model is reported to correctly describe steady state conditions but for transient state the threshold stress has to be divided into two additive terms, one which represents overcoming the effect of particles and the other the effect of particles on dislocation backstress. In constant strain rate tests both terms can be determined. STRUCTURE
OF OXIDE DISPERSION
STRENGTHENED
IRON AND NICKEL
ALLOYS FOR HIGH TEMPERATURES
D. Sporer, 0. Lang (PM HochtemperaturMetal GmbH, Reytte, Austria). It was reported that ODS Fe and Ni base alloys have unique structural characteristics which are a dispersion of small inert oxide particles, coarse elongated grains and a strong texture after secondary recrystallization. Differences between different classes of superalloy were outlined and discussed with reference to high temperature applications. Development of textures and effects on mechanical properties were reviewed. Grain control by thermomechanical processing was described.
during
LPS. Inhibition of grain growth microstructures were discussed.
and
PLASMA SINTERING OF ATTRITION MILLED COMPOSITE PRECURSORS
S.H. Kim, S.N. Sinha (University of Illinois, USA). Sintering characteristics of &AlzOs, made from attrition milled powders by plasma sintering were investigated with regard to process conditions. Milling was reported to be able to reduce particle size to 0.33 urn. Sintering at 8 kV gave density above 98%. The microstructure was shown to contain interpenetrating phase composites. Characteristics of powder and compacts were described. The potential of the technique was assessed. DYNAMICS OF MATERLALS PROCESSED
BY VIBRATORY MACHINES
A. Sverdlin et al. (Bradley University, USA). Interdependences between particulate and granular matter and processing machinery were discussed with regard to machine motions and material properties. A vibration/rheological model, to simulate material behavlour, in which interacting forces are considered, was described with reference to machine dynamics. Initial equations are reduced to a set of differential equations which were solved by numerical integration. Application to a vibratory conveyor, a compaction table and mill was outlined. Results were validated by experiment.
EURO follow
PM’95. The abstracts which are of papers which were
presented at the European Conference on Advanced PM Materials which was
held
in
Birmingham,
UK,
in
October 1995.
The paper discussed PM Fe and Cu based friction materials. An investigation in which amounts of additives were kept small was described. The influence of different graphite, Sic and kieselguhr contents were studied. Swelling during sintering was reported. This was attributed to high interface energies between metallic and non-metallic phases. SELF LUBRICATING IRON BASE MATERIALS MADE BY MECHANICAL ALLOYING
POROSITY AND FILTRATION CHARACTERISTICS
OF POROUS
FILTERS
SINTERED
COPPER BASE METAL
COMPOSITES
REINFORCED
WITH STEEL FIBRES
METAL INJECTION TUNGSTEN
MOULDING
OF
HEAVY ALLOYS
F. Petzold et al. (Fraunhofer Inst., Bremen, Germany) Applications of W heavy alloys were outlined. It was reported that complex shaped W heavy alloy parts could be made by MIM. Production of a radiation shield was described.
Structural parts STUDIES
OF GREEN AND SINTERED
IRON AND COPPER BASED FRICTION MATERIALS
C. Simons et al. (Forschungzentrum Jfilich GmbH, Jiilich, Germany).
46
MPR July/August
1996
Superalloys
P. Gheorge, M. Gheorge (ICEM SA, Romania). The sinterability of Cu base MMCs, reinforced with Fe or Cu plated Fe fibres was investigated by electron microscopy. Greater matrix diffusion was reported for the alloy with plated fibres. Mechanical and physical properties were described. MANUFACTURE OF METAL MATRIX COMPOSITES REINFORCED WITH CARBON FIBRE
C. Mircea, C. Novae (METAV SA, Romania). An investigation of Cu base MMCs, reinforced with C fibre, was described. The fibres were dispersed in the metal by a range of methods. Consolidation was by die pressing and solid or pressurized liquid phase sintering. Improved frictional properties were reported.
- PAST PRESENT
AND FUTURE
W.B. Eisen (Crucible Metals Corp, Plttsburg, USA). Application of PM Ni base superalloys as discs in gas turbines was discussed with reference to higher operating temperatures, engine reliability, process control to ensure high part quality and supersolvus heat treatment. Current development of alloys to meet the increased operating temperature requirement was noted. It was predicted that Ni based alloys would continue to find aerospace and ground based gas turbine applications. MODELLING
OF ELEVATED
TEMPERATURE
F.F. Ambrozio, P. Luzinette (Cidade University, Brazil). Methods for the study of filter characteristics were described. Results of measurements on 316L stainless steel were presented for a range of filter discs made from two different powder size distributions and pressed at 100 to 300 MPa. The filters were characterized for density, structure, porosity content, interconnected pores and filtration behaviour assessed by permeability and maximum pore size.
COUPLE
M. Lucaci et al. (METAV SA Romania). Tribological behaviour of a sintered Cu matrix/ceramic composite, in sliding contact with grey cast iron was investigated. Higher coefficients of friction and lower wear rates were reported for the composite materials.
PM SUPERALLOYS
B. Gunther et al. (Fraunhofer Inst., Bremen, Germany). It was reported that high energy ball milling homogeneously distributed graphite and hexagonal BN, up to ZOvol%,in Fe and Fe-Si alloys. Structural evolution, as a function of milling time was investigated. Refined lamellar structures were developed in the powders which were mainly retained on die pressing and sintering. Block-on-ring tests showed that friction diminished with milling time, attributed to structural refinement.
MATRIX
Metal injection moulding
SINTERED FRICTION MATERIALS
DISPERSION
DEFORMATION
OF
STRENGTHENED
SUPERALLOY
U. BBhm et al. (University of ErlangenNtirnberg, Germany). A model, based on Hasen-AlexanderIlschner theory, was used to describe steady state and transient creep deformation of Ni based ODS superalloy MA754 and the equivalent oxide free alloy Nimonic 75. The model is reported to correctly describe steady state conditions but for transient state the threshold stress has to be divided into two additive terms, one which represents overcoming the effect of particles and the other the effect of particles on dislocation backstress. In constant strain rate tests both terms can be determined. STRUCTURE
OF OXIDE DISPERSION
STRENGTHENED
IRON AND NICKEL
ALLOYS FOR HIGH TEMPERATURES
D. Sporer, 0. Lang (PM HochtemperaturMetal GmbH, Reytte, Austria). It was reported that ODS Fe and Ni base alloys have unique structural characteristics which are a dispersion of small inert oxide particles, coarse elongated grains and a strong texture after secondary recrystallization. Differences between different classes of superalloy were outlined and discussed with reference to high temperature applications. Development of textures and effects on mechanical properties were reviewed. Grain control by thermomechanical processing was described.