Abstract
The interplay between vacancies () and interstitial solutes (, N, and O) and its impact on thermodynamic properties of solid solutions are studied, starting from first principles calculations. A systematic comparison between the three solutes is performed, investigating , –, and – interactions. In the lattice, the strength of interactions is found to govern the dissolution properties. Next to vacancies, the competition between solute volume effects and interactions results in the preference of all the solutes to occupy off-centered sites. Low-energy configurations of small clusters are calculated for and up to 4. They are used to parametrize lattice interaction models at the atomic scale. A detailed analysis of the cluster properties suggests the relevance of many-body terms in these models. The accuracy of the resulting models is verified through their satisfactory prediction of vacancy-solute cluster properties beyond the fitting database. From these models, an entire set of clusters is generated with a new configurational space exploration method. Statistical treatment of the solid solution including these clusters is then achieved by means of low-temperature expansions, checked against Monte Carlo simulations in some specific conditions. Based on the calculation of equilibrium cluster distributions, it is shown that the solubility limit of oxygen in Fe, hardly measurable experimentally, is largely affected by the presence of small clusters.
8 More- Received 5 May 2014
- Revised 29 July 2014
DOI:https://doi.org/10.1103/PhysRevB.90.054112
©2014 American Physical Society