Self-diffusion in fcc metals

M. GARCÍA ORTEGA; S. RAMOS DE DEBIAGGI; A. M. MONTI

Minneapolis

Congreso; March Meeting 2000; 2000

American Physical Society

It is well known that several fcc metals exhibit an upward curvature in the Arrhenius plot of the self-diffusion coefficient at high temperatures. Three reasons have been proposed to explain it [1]: the contribution of more than one diffusion mechanism, the temperature dependence of the involved enthalpies and entropies, and the contribution of vacancy multiple jumps. In this work, we report the temperature dependence of the vacancy diffusion coefficient over a wide temperature range using molecular dynamics simulations and embedded atom interatomic potentials for Ni and Al. We investigate the details of the involved atomic jumps, paying particular attention to multiple ones and considering also the contribution of divacancies, within the limits imposed by the potentials. We compare our results to experimental data and previous results obtained through static calculations [2]. [1] G. De Lorenzi and F. Ercolessi, Europhys. Lett. 20 (4), 349 (1992). [2] S.B. Debiaggi, P.M. Decorte and A.M. Monti, Phys. Stat. Sol. (b) 195, 37 (1996).