ION-BEAM-INDUCED COMPOSITIONAL CHANGES IN ALLOYS AT ELEVATED-TEMPERATURES

Near-surface compositional changes in alloys during ion bombardment ha ve been studied theoretically. The scheme employed ensures pressure re laxation of the target, and the effects of preferential sputtering, co llisional mixing, radiation-enhanced diffusion, and Gibbsian and radia tion-induced segregation are allowed for. High-fluence composition pro files were determined directly from a nonlinear integro-differential e quation by means of an efficient iteration procedure developed recentl y. The dependence of the composition profile on input parameters such as target temperature and defect mobility was examined for Ni-Cu and N i-Pd alloys.