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Monte‐Carlo study of short‐range order reactions with activated diffusion
Author(s) -
Pitsch Wolfgang,
Gahn Ulrich
Publication year - 1993
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199301058
Subject(s) - vacancy defect , monte carlo method , kinetic monte carlo , diffusion , chemistry , physics , kinetics , crystal (programming language) , crystallography , thermodynamics , condensed matter physics , materials science , mathematics , quantum mechanics , statistics , programming language , computer science
By Monte Carlo simulations of short‐range order reactions in a rigid f.c.c. A 75 B 25 computer crystal, applying two diffusion mechanisms either in‐ or excluding an activation barrier against the vacancy migration, it is found that in both cases the same final states are approached which are the thermodynamic equilibrium states. The reaction kinetics in dependence on the number of performed vacancy steps, however, are different. – The morphology of the vacancy path is the same for both mechanisms: this path is uniformly distributed in the crystal steadily filling up the crystal volume during the reaction, thus this path does not form separated compact regions. The explanation of this behaviour is deduced from the observation that for both diffusion mechanisms the vacancy visits preferentially those lattice sites the local short‐range order of which is lower than at the average whereas those sites with larger short‐range order are left unvisited. Since sites with a certain degree of local short‐range order are uniformly distributed over the crystal the vacancy path, following these sites, is spread in the same way.