Elastic properties of disordered binary hcp-Fe alloys under high pressure: Effects of light elements

The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-random structure method. We found that the increase in the O content in hcp-Fe had a more pronounced effect on the sound velocity than Si, S, and C. The longitudinal wave velocity was decreased by ∼ 6% with 2% O content, which was a much greater decrease than the values of 0.6% and 2% induced by the same content of Si and S, respectively, under high pressures. Compared with the other three light elements, the longitudinal wave velocity of the Fe-C alloy exhibited the most gradual decreasing with increasing C content. In addition, the effects of different O and S contents on the anisotropy of hcp-Fe alloys strongly depended on the variation in pressure, whereas the pressure only slightly affected the anisotropy of Fe-Si alloy systems.