Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr
- National Research Center “Kurchatov Institute,” (Russian Federation)
- Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)
The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.
- OSTI ID:
- 22617229
- Journal Information:
- Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 1 Vol. 123; ISSN JTPHES; ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
APPROXIMATIONS
BCC LATTICES
BINARY ALLOY SYSTEMS
CHROMIUM COMPOUNDS
CONCENTRATION RATIO
COPPER COMPOUNDS
CORRELATIONS
FCC LATTICES
INTERACTIONS
IRON COMPOUNDS
MANGANESE COMPOUNDS
MEAN-FIELD THEORY
MONTE CARLO METHOD
NICKEL COMPOUNDS
SELF-DIFFUSION
STATISTICAL MODELS
VACANCIES