Interstitial point defects play a key role in the microstructural evolution of irradiated alloys, however, their thermodynamic and kinetic properties in multi-component systems are largely unknown. First-principles electronic structure techniques are powerful tools for obtaining insight into interstitial properties that cannot be resolved experimentally, such as solute-interstitial binding enthalpies. In this paper, first-principles methods are used to calculate formation and binding enthalpies of interstitials in the nickel (Ni)-chromium (Cr) binary system for different Cr configurations and concentrations. This work reveals that the dumbbell interstitial is the most stable configurations for interstitials with 0, 1, or 2 Cr present in the local environment. However, the and interstitial dumbbells become increasingly stable with increasing Cr concentration, which could reduce the rotation barriers for Ni-Cr and Cr-Cr dumbbells and thereby enhance interstitial diffusion. Strong binding is observed for 1-3 Cr in or near the dumbbell and configurations with Cr in the dumbbell are most stable. The Ni-Cr mixed dumbbell and Cr-Cr dumbbell have binding enthalpies of 0.50 and 0.92 eV, respectively. These high binding enthalpies are expected to hinder dissociation of the Cr-interstitial complex, suggesting that even isolated Cr solutes could serve as temporary traps for interstitials. Temporary trapping of interstitials could aid in recombination with vacancies in the system and reducing radiation assisted microstructural changes. This trapping mechanism is reinforced with an additional Cr atom present in the local environment, which strengthens the Cr-interstitial binding and will further hinder dissociation of the solute-interstitial complex.
[1]
Stefano Curtarolo,et al.
Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys
,
2005,
cond-mat/0502465.
[2]
G. Ceder,et al.
The Alloy Theoretic Automated Toolkit: A User Guide
,
2002,
cond-mat/0212159.
[3]
G. Ceder,et al.
Automating First-Principles Phase Diagram Calculations
,
2002,
cond-mat/0201511.
[4]
G. Kresse,et al.
From ultrasoft pseudopotentials to the projector augmented-wave method
,
1999
.
[5]
Burke,et al.
Generalized Gradient Approximation Made Simple.
,
1996,
Physical review letters.
[6]
Kresse,et al.
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.
,
1996,
Physical review. B, Condensed matter.
[7]
Blöchl,et al.
Projector augmented-wave method.
,
1994,
Physical review. B, Condensed matter.
[8]
Hafner,et al.
Ab initio molecular dynamics for liquid metals.
,
1995,
Physical review. B, Condensed matter.
[9]
W. Schilling.
Self-interstitial atoms in metals
,
1978
.
[10]
R. Johnson.
Point-Defect Calculations for an fcc Lattice
,
1966
.