Tracer diffusion of 65Zn, 110mAg and 88Y in QE22 metal matrix composite

Tracer diffusion of 65Zn, 110mAg and 88Y in QE22 metal matrix composite was measured by serial sectioning method in the temperature interval 646–728 K. The volume diffusion coefficients of Zn and Ag in the un-reinforced alloy follow Arrhenius dependences with frequency factors D0 = 9.5 × 10−5 and 6.0 × 10−3 m2 s−1 and the activation enthalpies 125.3 and 153.5 kJ mol−1, respectively. In the case of the reinforced alloy, the effective diffusion coefficients Deff were obtained and interface diffusion coefficients Di in the interface boundaries were estimated. Both temperature dependences of Deff and Di were not Arrhenius-type. This feature was explained by the large difference in coefficients of the thermal expansion of the metal matrix and the reinforcement. In the case of 88Y diffusion in un-reinforced QE22 alloy, it was found that yttrium diffuses along dislocations that act as paths of rapid diffusion. Diffusivity of 88Y along dislocations, a2sDd, was estimated.