NUMERICAL STUDY OF COLLISIONAL MIXING - THE FELU SYSTEM REVISITED

We present a numerical study of the mixing of an FeLu alloy due to bom bardment by 5 keV Ar+ and Xe+ ions. A dual approach is used to calcula te the evolution of concentration profiles in a multi-component target with the fluence of irradiating ions. In a first step, Monte Carlo si mulation is used to calculate the atomic relocation in a collision cas cade set up by the bombarding ion. In a second step, the change of the concentration profiles due to atomic relocation is calculated using a finite-difference scheme. We check the numerical results using a diff usion approximation to the underlying evolution equations, and find go od agreement. The approximation shows that the concentration evolution can be determined analytically from the preferential relocation of ea ch species over the average relocation and the mean surface recession speed. For the FeLu system, we find that by varying one or several of the model parameters in our simulation - like the cutoff of the potent ial, or the displacement threshold - the preferential relocation, and hence the steady-state profiles, are changed. These changes can be und erstood qualitatively in terms of available analytical models. We comp are with published results on this system, and discuss the discrepanci es found.