ELECTRON-IRRADIATION EFFECT ON PHASE-TRANSFORMATION IN TI-NI SHAPE-MEMORY ALLOY

The sensitivity of phase transformation in Ti-Ni shape memory alloy to electron irradiation has been investigated by means of HVEM at room t emperature. In the present study, the phase transformation of this all oy finally went to the amorphous phase. The amorphization process can be categorized according to the following three types. (1) The B2 phas e transformed to the amorphous phase successively with the increase of dose. (2) The martensitic phase transformed to the B2 phase at the be ginning of irradiation. The transformation to the amorphous phase prog ressed successively. (3) The martensitic phase transformed to the amor phous phase directly. The amorphization progressed irregularly. The cr itical dose for the amorphization in all three processes has been inve stigated. The critical doses for the amorphization were quite sensitiv e to the micro-chemical composition; the dose of the stoichiometric co mposition was relatively high.