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Diffusion by vacancy mechanism in Ni, Al, and Ni 3 Al: Calculation based on many‐body potentials
Author(s) -
Debiaggi S. B.,
Decorte P. M.,
Monti A. M.
Publication year - 1996
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221950105
Subject(s) - vacancy defect , diffusion , intermetallic , atom (system on chip) , relaxation (psychology) , thermodynamics , materials science , arrhenius equation , jump , self diffusion , condensed matter physics , chemistry , crystallography , activation energy , physics , metallurgy , alloy , quantum mechanics , psychology , social psychology , self service , business , marketing , computer science , embedded system
The self‐diffusion coefficients for the monovacancy mechanism, described in terms of the Arrhenius law, are calculated for Ni, Al, and the intermetallic compound Ni 3 Al by computer simulation techniques. Many‐body interatomic potentials, based on the embedded atom model, are used together with the static relaxation method to study the static and dynamic properties of vacancies. The defect formation and migration energies, their corresponding relaxation volumes and vibration entropies, are evaluated. Special interest is devoted to the results obtained for Ni diffusion in Ni 3 Al. The present calculations predict that simple vacancy‐Ni atom interchange jumps (both of ordered and disordered types) are energetically more favourable than the correlated six‐jump cycles. Even though a difference in energies of δ = 0.35 eV favours migration via ordering jumps with respect to disordering jumps, the entropy factors behave in an opposite way suggesting that both types of jumps contribute to the Ni diffusion. Only for low temperatures ( T ≤ 770 K) disordering jumps can be neglected. For this case, a pre‐exponential factor D 0 = 0.2 × m 2 s −1 is obtained.