Diffusion of tungsten in chromium: Experiments and atomistic modeling

Abstract

The solute diffusion of tungsten at low concentrations in chromium has been investigated both by experiments and computational methods. From finite-source diffusion experiments measured with an Electron Probe Micro Analyzer at temperatures from 1526 to 1676K, it was found that the diffusivity of tungsten in chromium follows the Arrhenius relationship D=D0exp-QRT, where the activation energy was found to be Q=386±33kJ/mol. Diffusion of tungsten in chromium was investigated computationally with both the activation–relaxation technique (ART) and molecular dynamics (MD) using a hybrid potential. From ART, the effective diffusion activation energy was determined to be Q=315±20kJ/mol based on a multi-frequency model for a monovacancy mechanism. From MD, the square displacement of tungsten was analyzed at temperatures between 1200 and 1700K, and the diffusion activation energy was determined to be Q=310±18kJ/mol. In spite of possible complications arising due to experimental compositions away from the dilute limit, the agreement between experiments and simulations falls within the calculated uncertainties, supporting a monovacancy mechanism for diffusion of tungsten in chromium.