Interdiffusion in B2 type intermetallic compound FeAl under high pressures

Abstract

Interdiffusion coefficient in the B2 FeAl phase at 46-50 at%Al has been measured in the temperature range from 1173 to 1473 K under the pressure from 0.1 MPa to 5 GPa. The activation volume for interdiffusion, ΔV̄, derived from the pressure dependence of interdiffusion coefficient is found to be 0.58-0.90Vm (Vm: molar volume of alloys), which is comparable to or larger than 0.4-0.6Vm for the monovacancy mechanism in bcc pure metals or random alloys. The value of ΔV̄ increases with increasing temperature and also with deviating from stoichiometry, suggesting that divacancy contributes to the diffusion in higher temperatures and in the region of off-stoichiometry.