The r phase transformation in Ti-49Ni(at.%) shape memory alloy ribbons fabricated by melt spinning

The B2(cubic)-R(rhombohedral) transformation in Ti-Ni alloys has been known to be very attractive for its small transformation hysteresis and superior thermal cycling characteristics. Many methods for inducing the B2-R transformation were developed, that is, thermo-mechanical treatments(annealing at intermediate temperature after cold working) of near equiatomic Ti-Ni alloys, aging of Ni-rich Ti-Ni alloys, substitution of Fe, Al for Ti in near equiatomic Ti-Ni alloys and thermal cycling. Recently, the present authors found that Ti-rich Ti-Ni binary alloy ribbons produced by melt spinning exhibited the B2-R transformation. Until now, only thermo-mechanical treatments and thermal cycling have been known to induce the B2-R transformation in Ti-rich Ti-Ni binary alloys. Therefore, rapid solidification process by melt spinning was thought to be a new method for inducing the B2-R transformation in Ti-rich Ti-Ni binary alloys. The purpose of the present study is to investigate transformation behavior of Ti-rich Ti-Ni binary alloy ribbons produced by melt spinning.