EFFECTS OF RESIDUAL STRAIN ON DEFORMATION PROCESSES OF NEUTRON-IRRADIATED TI-NI AND TI-PD SHAPE-MEMORY ALLOYS

Ti-Ni and Ti-Pd shape memory alloys (SMA) reveals good workability and shape memory properties and these SMAs seem to be one of hopeful func tional materials in a severe irradiation field. The effects of irradia tion induced residual strain on the deformation processes of Ti-Ni and Ti-Pd SMAs after neutron irradiation with fluences (E > 1 MeV) up to 3.9 x 10(24) m(-2) at Japan Materials Testing Reactor (JMTR) were inve stigated by the remote controlled X-ray diffraction measurement. Resid ual strains of Ti-Ni SMAs took place over damage of 0.1 dpa and the st rains were not completely removed by post-irradiation annealing at 473 , 523 and 573 K. On the other hand, residual strains of Ti-Pd SMAs sca rcely occurred after irradiation, and furthermore, the Ti-Pd SMA seems to be an irradiation-resistant material. This may be explained by a d ifference between the irradiation response of a parent phase and that of a martensitic phase to neutron irradiation. Deformation processes o f SMAs are associated with stress fields generated by irradiation in a parent phase with B2 type ordered structure or in a martensitic phase with 2H and 9R type close-packed structures.