Electron Irradiation Induced Amorphization at Dislocations in NiTi

Abstract

Process of the crystalline-amorphous transition in NiTi induced by electron irradiation has been investigated by a combination of high voltage and conventional electron microscopy, with emphasis on the study of the initiation sites of the transition. At the beginning stage of irradiation, a localized amorphization takes place at dislocations so that a cylindrical amorphous region is formed along individual dislocation lines. Continued irradiation brings about the lateral growth of the cylindrical amorphous regions. This is the first time such a preferential transition at dislocations has been observed in metal crystals.