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Initial recrystallization temperature of sintered silver-transition metal composites
and 33 vol% stainless steel wire, by winding and hot pressing techniques. These were tested in tension and compression in the direction of the wires. The resulting matrix dislocation configurations were studied using thin film electron microscopy. The tensile properties of the composites were in good agreement with predictions calculated from the law of mixtures. In the case of compression, the elastic limit, the micro-yield stress, and the macro-yield stress were higher than predicted. F o r a given strain and volume fraction of reinforcement, the dislocation configuration and density were independent of distance from the wire-matrix interface and were similar to those in similarly strained pure aluminium. (70/3/48)
Deformation behaviour of continuousfiber metal-matrix composite materials Cheskis, H. P. and Heckel, R. W. Metallurgical Transactions, Vol 1, No 7, pp 1931 - 1942 (July 1970} X-ray diffraction techniques were used successfully to study the stress-strain behaviour of b o t h matrix and fibres in situ, during the tensile testing of aluminium reinforced with tungsten wires or boron fibres. The results indicated that the composites exhibited rule-of-mixture behaviour during deformation, provided that initial residual stresses in the composite were allowed for. The residual stresses were found to significantly influence the yield behaviour. Stresses produced by Poisson's ratio differences between matrix and fibre were negligible. (70/3[49)
The development of a pseudo-eutectie nickel based composite alloy Shen, Yuan-Shon and Griffiths, L. B. Metallurgical Transactions, Vol 1, No 8, pp 2305 - 2313 (August 1970) Directional solidification of a Ni-Cr-Be alloy produced a pseudo-eutectic microstructure, consisting of about 45 vol% of hard 'fibres' of nickel beryllide in a soft, Ni-Cr solid solution matrix. The tensile properties of the alloy were controlled by the hard phase. The work-hardening rate was greater than for commercial nickel alloys. Additions of A1, Mo and W improved the mechanical properties of the alloy, as did certain heat treatments. (70•3•50)
Experience with the heat processing of cermet components of complex shape Gurevich, V. G. et al Soviet Powder Metallurgy, No 9, pp 7 5 9 - 763 (September 1969}
384
COMPOSITES December 1970
Methods o f hardening a composite material, comprising carbon steel with 5% glass and prepared by powder metallurgy, were studied. It was found possible to quench components of simple shape from 870°C into water without cracks forming. F o r more complex shapes, satisfactory hardening with the minimum of cracking, was achieved by quenching from 8 2 0 + IO°C into a 20% aqueous solution of sodium hydroxide. (70/3/5 I)
Influence of certain technological factors on the strength and antifrietion properties of sulfided ferro-graphite (Part 1) Korkh, L. M. et al Soviet Powder Metallurgy, No 9, pp 751 - 753 (September 1969) The strength and wear properties were measured of antifriction materials, prepared by powder metallurgy and consisting of Fe containing 4% ZnS and 3% graphite. The wear against a rotating steel surface was measured as a function of speed of rotation and of the particle size of the original composite powder. The wear properties improved with decreasing particle size. (70/3/52)
Effect of some technological factors on the strength and antifriction properties of sulfidized iron-graphite materials (Part 2) Korkh, L. M., Pugina, L. I. and Mamykin, E. T. Soviet Powder Metallurgy, No 10, pp 8 2 4 - 828 (October 1969) The strength and anti-friction properties of a composite of iron containing 3% graphite and 4% ZnS and prepared by powder metallurgy, were studied as a function of the porosity and microstructure of the material, the porosity being between 1 and 20 vol%. The wear properties in dry wear tests improved markedly with reduction in porosity. The highest wear resistance was obtained for a microstructure containing up to 15% cementite inclusions. (70/3/53)
Influence of filament orientation and fabrication variables on the properties of fiber-reinforced metals Bhattacharyya, S. and Parikh, N. M. Metallurgical Transactions, Vol 1, No 5, pp 1437 - 1448 (May 1970} Composites of silver reinforced with 2 to 33 vol% of tungsten wires were prepared by an electroplating technique followed by pressing and sintering. Measurements were made of tensile properties on specimens with fibre orientations between 0 ° and 90 °
to the tensile axis. The observed strengths were in fair agreement with the law of mixtures. Fibre misalignmerit of greater than about 10 ° to the tensile axis, drastically reduced strength, but misalignment of less than 10 ° caused improved ductility without a significant reduction in strength. Five distinct types of fracture path were observed depending on the fibre orientation. The fracture surfaces were studied with a scanning electron microscope. The tungsten wires exhibited both brittle and ductile fracture. (70/3/54)
Initial recrystallization temperature of sintered silver-transition metal composites Pravoverov, N. L. and Tribunskaya, I. A. Soviet Powder Metallurgy, No 12, pp 1006 - 1011 (December 1969} Powder metallurgical techniques were used to prepare composites of silver with small additions of Ti, V, Mn, Fe, Co, or Cr. Specimens were annealed and then worked at r o o m temperature or liquid nitrogen temperature. The recrystallization temperature was then determined by metallographic observation, by x - r a y diffraction, and by micro-hardness measurements. The additions of Ti, V, Mn, Fe and Co lowered the recrystallization temperature from 170°C to between 100 and 160°C, whereas Cr increased it from 170 to about 200°C. (70/3/55)
Investigations of ThO2 -Ni and ZrO2-Mo eermets with additions of Cr (in German) Jangg, G. et al Berichte der Deutschen Keramischen Gesellschafl, Vol 47, No 9, pp 563 - 570 (September 1970) It was found possible to prepare low-porosity composites of ZrO2 particles dispersed in Mo and Mo-Cr alloys, both by hot pressing and by sintering. ThO2-Ni composites could only be satisfactorily prepared by hot pressing. The ZrO2-Mo composites had satisfactory transverse rupture strengths and thermal shock resistance. Their poor oxidation resistance was improved by additions of Cr. The ThO2 - N i composites had good oxidation resistance. Their poor strength was improved somewhat by additions of Cr. (70/3/56)
Mechanical properties of refractory metal wires for high temperature reinforcement Burwood-Smith, A. Fibre Science and Technology, Vol 3, No 2, p 105 (October 1970) The results of an investigation into the tensile and stress-rupture properties of
Deformation behaviour of continuousfiber metal-matrix composite materials Cheskis, H. P. and Heckel, R. W. Metallurgical Transactions, Vol 1, No 7, pp 1931 - 1942 (July 1970} X-ray diffraction techniques were used successfully to study the stress-strain behaviour of b o t h matrix and fibres in situ, during the tensile testing of aluminium reinforced with tungsten wires or boron fibres. The results indicated that the composites exhibited rule-of-mixture behaviour during deformation, provided that initial residual stresses in the composite were allowed for. The residual stresses were found to significantly influence the yield behaviour. Stresses produced by Poisson's ratio differences between matrix and fibre were negligible. (70/3[49)
The development of a pseudo-eutectie nickel based composite alloy Shen, Yuan-Shon and Griffiths, L. B. Metallurgical Transactions, Vol 1, No 8, pp 2305 - 2313 (August 1970) Directional solidification of a Ni-Cr-Be alloy produced a pseudo-eutectic microstructure, consisting of about 45 vol% of hard 'fibres' of nickel beryllide in a soft, Ni-Cr solid solution matrix. The tensile properties of the alloy were controlled by the hard phase. The work-hardening rate was greater than for commercial nickel alloys. Additions of A1, Mo and W improved the mechanical properties of the alloy, as did certain heat treatments. (70•3•50)
Experience with the heat processing of cermet components of complex shape Gurevich, V. G. et al Soviet Powder Metallurgy, No 9, pp 7 5 9 - 763 (September 1969}
384
COMPOSITES December 1970
Methods o f hardening a composite material, comprising carbon steel with 5% glass and prepared by powder metallurgy, were studied. It was found possible to quench components of simple shape from 870°C into water without cracks forming. F o r more complex shapes, satisfactory hardening with the minimum of cracking, was achieved by quenching from 8 2 0 + IO°C into a 20% aqueous solution of sodium hydroxide. (70/3/5 I)
Influence of certain technological factors on the strength and antifrietion properties of sulfided ferro-graphite (Part 1) Korkh, L. M. et al Soviet Powder Metallurgy, No 9, pp 751 - 753 (September 1969) The strength and wear properties were measured of antifriction materials, prepared by powder metallurgy and consisting of Fe containing 4% ZnS and 3% graphite. The wear against a rotating steel surface was measured as a function of speed of rotation and of the particle size of the original composite powder. The wear properties improved with decreasing particle size. (70/3/52)
Effect of some technological factors on the strength and antifriction properties of sulfidized iron-graphite materials (Part 2) Korkh, L. M., Pugina, L. I. and Mamykin, E. T. Soviet Powder Metallurgy, No 10, pp 8 2 4 - 828 (October 1969) The strength and anti-friction properties of a composite of iron containing 3% graphite and 4% ZnS and prepared by powder metallurgy, were studied as a function of the porosity and microstructure of the material, the porosity being between 1 and 20 vol%. The wear properties in dry wear tests improved markedly with reduction in porosity. The highest wear resistance was obtained for a microstructure containing up to 15% cementite inclusions. (70/3/53)
Influence of filament orientation and fabrication variables on the properties of fiber-reinforced metals Bhattacharyya, S. and Parikh, N. M. Metallurgical Transactions, Vol 1, No 5, pp 1437 - 1448 (May 1970} Composites of silver reinforced with 2 to 33 vol% of tungsten wires were prepared by an electroplating technique followed by pressing and sintering. Measurements were made of tensile properties on specimens with fibre orientations between 0 ° and 90 °
to the tensile axis. The observed strengths were in fair agreement with the law of mixtures. Fibre misalignmerit of greater than about 10 ° to the tensile axis, drastically reduced strength, but misalignment of less than 10 ° caused improved ductility without a significant reduction in strength. Five distinct types of fracture path were observed depending on the fibre orientation. The fracture surfaces were studied with a scanning electron microscope. The tungsten wires exhibited both brittle and ductile fracture. (70/3/54)
Initial recrystallization temperature of sintered silver-transition metal composites Pravoverov, N. L. and Tribunskaya, I. A. Soviet Powder Metallurgy, No 12, pp 1006 - 1011 (December 1969} Powder metallurgical techniques were used to prepare composites of silver with small additions of Ti, V, Mn, Fe, Co, or Cr. Specimens were annealed and then worked at r o o m temperature or liquid nitrogen temperature. The recrystallization temperature was then determined by metallographic observation, by x - r a y diffraction, and by micro-hardness measurements. The additions of Ti, V, Mn, Fe and Co lowered the recrystallization temperature from 170°C to between 100 and 160°C, whereas Cr increased it from 170 to about 200°C. (70/3/55)
Investigations of ThO2 -Ni and ZrO2-Mo eermets with additions of Cr (in German) Jangg, G. et al Berichte der Deutschen Keramischen Gesellschafl, Vol 47, No 9, pp 563 - 570 (September 1970) It was found possible to prepare low-porosity composites of ZrO2 particles dispersed in Mo and Mo-Cr alloys, both by hot pressing and by sintering. ThO2-Ni composites could only be satisfactorily prepared by hot pressing. The ZrO2-Mo composites had satisfactory transverse rupture strengths and thermal shock resistance. Their poor oxidation resistance was improved by additions of Cr. The ThO2 - N i composites had good oxidation resistance. Their poor strength was improved somewhat by additions of Cr. (70/3/56)
Mechanical properties of refractory metal wires for high temperature reinforcement Burwood-Smith, A. Fibre Science and Technology, Vol 3, No 2, p 105 (October 1970) The results of an investigation into the tensile and stress-rupture properties of