Silver diffusion in commercial QE22 magnesium alloy with Saffil fiber reinforcement

Abstract Diffusion of 110m Ag in commercial QE22 magnesium alloy with and without short Saffil fibers reinforcement is measured by the radiotracer technique in the temperature interval 648–728 K. The obtained diffusion coefficients D v in the experimental alloys without reinforcement allow to evaluate the influence of the interface between matrix and Saffil fibers on the effective diffusion coefficient D eff and estimate the interface diffusion coefficient D i of Ag in interphase boundaries. The results obtained for un-reinforced alloy show typical Arrhenius behavior. The pre-exponential factor D 0 = 6 - 3 + 5 × 10 - 3 m 2 s - 1 and activation enthalpy Q = 154 ± 3 kJ mol −1 are evaluated. It is observed that the temperature dependence of diffusion coefficients D eff and D i is not Arrhenius-like in the studied temperature interval. This behavior is attributed to relaxation of thermo-elastic stresses in the composite as an effect of large difference between coefficients of thermal expansion (CTE) of Saffil fibers and metal matrix. The maximum values of D eff and D i , respectively, lies close to 693 K, where CTE has a minimum.