First Principles Study on Effect of B Addition on Oxidation Resistance of MoSi₂-based Compound

Based on the first-principles calculation method, the influence of B addition on the oxidation behavior of compound pair MoSi₂/MoB was comprehensively investigated. The results showed that the oxygen adsorption energy at the interface of compound pair MoSi₂/MoB, and of the compound MoB itself is lower and the diffusion activation energy of oxygen atom passing through the interface MoSi₂/MoB is also lower, which may facilitate the rapid oxidation of the compound surface during the initial oxidation stage and enable the rapid formation of a protective oxide scale. When the oxidation process reached a stable state, a scale of borosilicate with 6%B (atomic fraction) may form on the compound surface with the lowest oxygen diffusion coefficient, namely, excellent oxidation resistance of the oxide scale. Therefore, precise control of B-doping is a promising strategy for designing MoSi₂-based compound Mo-Si-B of high oxidation resistance.