A Ni-Ti-rare earth alloy and a method of processing a Ni-Ti-rare earth alloy

摘要

A superelastic Ni-Ti-rare earth alloy which comprises (in atomic %): about 35-65 % nickel, about 1.5-15 % in total of rare earth elements (preferably Er), boron up to about 0.1 %, with the balance being titanium. Up to about 14.9 atomic % of additional alloying elements may also be present. Also a method of processing said alloy with the composition (in atomic %) of: about 40-60 % nickel, about 1.5-15 % in total of rare earth elements, boron up to about 0.1 %, with the balance being titanium, by homogenizing to form spheroids of a rare earth-rich second phase in the alloy. The alloy is homogenized at a temperature below the incipient melting point (Tc) of the rare earth-rich second phase (e.g. in the range of about 750- 875 °C) for about 24-72 hours. The homogenized alloy can be heat-treated by thermal cycling, either between temperatures above and below Tcor between temperatures below Tc. Alternatively it can be water quenched, furnace cooled, cold worked to achieve at least 30% reduction in a dimension or hot-worked at a temperature in the homogenization range while an electric field is applied.