THE HEAT-OF-MIXING EFFECT ON ION-INDUCED GRAIN-GROWTH

Irradiation experiments were conducted on multilayer (ML) and coevaporated (CO) thin films in order to examine the role that the heat-of-mixing (DELTA-H(mix) 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 DELTA-H(mix) 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 DELTA-H(mix) 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.