First principles calculation of elastic properties of Fe–C alloys: Effect of interstitial and substitutional carbon element

Abstract

The effect of different incorporation mechanisms on the elastic properties of hcp Fe–C alloys at high pressures is investigated using density functional theory combined with Monte Carlo special quasi-random structure method. It is found that the different incorporation mechanism has little effect on the bulk modulus B and the compressional wave velocity Vp of hcp Fe–C alloys. However, the values of the shear modulus G and the shear wave velocity Vs in substitutional doping form are generally larger than those in interstitial doping form, which are 17% and 8% higher than G and Vs in interstitial doping form at 250 GPa and 2.5 wt% carbon content. Interestingly, the elastic properties of Fe–C alloy are almost unaffected by interstitial doping sites (octahedral central site and tetrahedral central site) below 250 GPa.