Method of manufacturing high-temperature shape memory alloys

摘要

A method of manufacturing a high-temperature shape memory alloy includes the steps of cold-working a high-temperature shape memory alloy, in which a reverse martensite transformation start temperature (As) in a first heating after cold working reaches 350 DEG C. or above. Thereafter, the cold-worked alloy undergoes a first heat treatment for a period of time within the incubation time required for recrystallization or less, and at a temperature higher than a reverse martensite transformation finish temperature (Af). Finally, the resultant alloy is annealed with a second heat treatment, at a temperature which is not less than the plastic strain recovery temperature and not more than the recrystallization temperature. Specifically, the first heat treatment is performed for a period of three minutes or less at a temperature which exceeds 500 DEG C. and which is lower than the melting point of the alloy. The composition of the high-temperature shape memory alloy is Ti50Ni50-xPdx (x being 35 to 50 at %), Ti50-xNi50Zrx (x being 22 to 30 at %), Ti50-xNi50Hfx (x being 20 to 30 at %) or the like.