Effect of projectile mass on amorphization of CuTi

Various intermetallic compounds are shown to be amorphized by electron and ion irradiations below a critical temperature. The critical temperature for amorphization is higher for ion irradiation than for electron irradiation. In the present work, the effect of projectile mass is studied in amorphization of CuTi with electron, Ne⁺, Kr⁺ and Xe⁺. The critical temperature was found to increase monotonically with projectile mass from 185K for electron to 543K for Kr⁺ and Xe⁺. The kinetics of crystalline to amorphous transition was studied by measuring the integrated intensity of diffuse rings on electron diffraction patterns. The analysis of the results of this measurement by Gibbons model indicated that the direct amorphization occurs in a single damage zone with Kr⁺, while overlapping of three damage zones is required for amorphization with Ne⁺. In the light of these observations, the relation between the structure of irradiation damage and the crystalline to amorphous transition, and the projectile mass dependence of the critical temperature for irradiation-induced amorphization will be discussed.