The heat-of-mixing effect on ion-induced grain growth

Abstract

Irradiation experiments were conducted on multilayer (ML) and coevaporated (CO) thin films in order to examine the role that the heat-of-mixing (ΔHmix) has in ion-induced grain growth. Room-temperature irradiations using 1.7-MeV Xe ions were performed in the High Voltage Electron Microscope at Argonne National Laboratory. The ML films (Pt-Ti, Pt-V, Pt-Ni, Au-Co, and Ni-Al) spanned a large range of calculated ΔHmix values. Comparison of grain growth rates between ML and CO films of a given alloy confirmed a heat-of-mixing effect. With the exception of the Pt-V system, differences in grain growth rates between ML and CO films varied according to the sign of the calculated ΔHmix of the system. Substantial variations in growth rates among CO alloy films experiencing similar displacement damage demonstrated that a purely collisional approach is inadequate for describing ion-induced grain growth. Therefore consideration must also be given to material-specific properties, such as cohesive energy.