NICKEL-TITANIUM-ZIRCONIUM(HAFNIUM) SHAPE MEMORY ALLOY IMPROVED IN WORKABILITY

摘要

PROBLEM TO BE SOLVED: To raise the initial inverse transformation temp. and to improve workability by incorporating specific amounts of B into an Ni-Ti-Zr(Hf) shape memory alloy. ;SOLUTION: This shape memory alloy has a composition consisting of, by atom, 45-50% Ni, 9-16% (in total, in the case of both) of either or both of Zr and Hf, ≤3% B, and the balance Ti and also has ≥100°C initial inverse transformation temp. (As point). Workability can be improved by adding specific amount of B to the Ni-Ti-Zr(Hf) ternary shape memory alloy. This effect can be observed from an additive quantity as small as about 0.1 atomic % and can be obtained sufficiently at an additive quantity of about 0.5 to 1.0 atomic %. In the region exceeding 1%, the effect of addition is gradually saturated. When the additive quantity exceeds 3%, the effect of raising inverse transformation temp. is reduced, and the purpose of providing an alloy having 100°C As point cannot be obtained.;COPYRIGHT: (C)1998,JPO