MONTE CARLO STUDY OF THE VACANCY MECHANISM IN DILUTE FCC BINARY ALLOYS

The vacancy mechanism is simulated by means of Monte Carlo (MC) method. In this model, the impurity diffusion occurs by migration of substitutional atoms B via the exchange with vacancies whose frequencies near a solute atom differ from a free vacancy. Whenever a defect leaves the lattice, periodic boundary conditions are made to bring it into the lattice. The solute concentration profiles are given using a technique developed by Murch which has been shown to be equivalent to a finite source. The fit of these profiles allows the comparison between our results and analytical solutions. The parameters extracted from a Gaussian function fit which agrees well with numerical profiles are in very good quantitative agreement with theoretical predictions.