Properties and microstructure of nickel and nickel-alloy wire produced by working sintered blanks
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A study was made of the mechanical properties of 3-,2-, and 1-mm-diameter wires (reductions of ε = 35, 55, and 75%, respectively) in unalloyed nickel and nickel alloys, produced by powder-metallurgy techniques from carbonyl nickel powder.
The mechanical properties (σV,σS,δ, and number of bends n) of such wire in the work-hardened condition are determined by its degree of cold deformation: The maximum values of strength (σV andσS) and the minimum values of ductility characteristics (δ and n) correspond to the highest value ofε, i.e., 75%.
The elongation and number of bends of wires of all diameters gradually improve as the annealing temperature is raised from 500 to 700°C, which can be ascribed to both propagation of recrystallization processes and a slight refining of metal brought about by annealing in a hydrogen atmosphere with a dew point of between −35 and −40°C.
The mechanical properties of 1-mm-diameter wire (ε = 75%) in alloys with fine oxide inclusions vary within a narrow range and, in spite of substantial differences in recrystallization temperature, depend only little on alloy composition, which is due to the severe deformation of the materials and the effect that such deformation has on dispersion-hardened alloys.
A Ni + 4% W alloy has a high recrystallization temperature, and, because of this, wire in this alloy retains its high strength and low ductility properties right up to an annealing temperature of 700°C.
Unalloyed-nickel and nickel-alloy wires produced by cold-working sintered blanks can be successfully used in either the work-hardened or annealed condition. Heat-treatment parameters must be chosen individually for each specific type of operation.
KeywordsNickel Ductility Oxide Inclusion Cold Deformation Nickel Powder
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- 1.B. A. Borok et al., Poroshkovaya Met., No. 4 (1968); No. 12 (1969).Google Scholar
- 2.M. V. Stepanova et al., Izv. Vysshikh Uchebn. Zavedenii, Tsvetn. Met., No. 6, 144 (1972).Google Scholar
- 3.M. V. Stepanova et al., Izv. Vysshikh Uchebn. Zavedenii, Tsvetn. Met., No. 1, 150 (1973).Google Scholar
- 4.D. V. Lebedev et al., Probl. Prochnosti, No. 7 (1970).Google Scholar