Diffusion of zinc in commercial Al-Zn alloys under high pressure

Abstract

The effective interdiffusion coefficients of zinc in commercial Al-Zn alloys are obtained within the temperature range 773 to 883 K under pressures from 0 to 0.41 GPa. From the temperature dependence of the effective interdiffusion coefficients, the activation energies for the 701, 703 and 705 alloys are evaluated to be 125, 124 and 127 kJ/mol respectively, and their pre-exponential factors are 3.0 × 10−5, 4.0 × 10−5, and 3.9 × 10−5 m2/s respectively. The activation volumes, ΔV, for diffusion of zinc in the commercial Al-Zn alloy are 8.30 × 10−6, and 8.60× 10−6 m3/mol at 823 and 883 K, respectively. The ratios of the activation volume to the molar volume of aluminum, ΔV/V0, are 0.83 at 823 K and 0.86 at 883 K. This means that the diffusion of zinc in the commercial Al-Zn alloys occurs predominantly by the monovacancy mechanism at 823 and 883 K.