The influence of Cr on He trapping behavior and the coupling effect of Cr/He on the mechanical behavior of the C14-Laves Fe2W phase: First–principle and quasi-harmonic approximation studies

Abstract

The influence of chromium (Cr) on the thermal properties of C14–Laves Fe2W phase were studied in detail based on the quasi–harmonic approximation. The effect of Cr on the helium (He) trapping behavior of the C14–Laves Fe2W phase was also investigated based on the defect formation energy with density functional theory (DFT). The results indicated that Cr could not only decrease the values of the Gibbs energy and bulk modulus of the C14–Laves Fe2W phase, but could also increase the thermal expansion coefficient of the C14–Laves Fe2W phase. In addition, Cr could reduce the capacity of the C14–Laves Fe2W phase to trap He. The coupling effect of Cr and He on the mechanical behavior of the C14–Laves Fe2W was studied, wherein both Cr and He could reduce the tensile strength that was aligned to the [0001] of C14–Laves Fe2W phase. The relation between the mechanical behavior of the C14-Laves Fe2W or Cr doped Fe2W phases and their thermal properties were also discussed. The fracture mechanisms of the C14–Laves Fe2W phases, with or without Cr/He–doping, along the (0001) grain plane was analyzed based on the charge density and partial densities of states (pDOS).