FORMATION MECHANISM OF A CRYSTALLINE AG50PD50 SOLID-SOLUTION BY IMPACT BALL-MATERIALS INTERACTION

The formation of the crystalline Ag50Pd50 solid solution during mechan ical alloying under shock interaction of Ag and Pd metallic powders ha s been studied using electron microscopy and X-ray diffraction. The pr ocess involved for impact interaction occurs via the incorporation of the small Pd particles into the Ag matrix in which, under the action o f mechanical strain, the mutual diffusion of Ag and Pd leads to the fo rmation of two solid solutions, one rich in Ag and the other rich in P d. Further grinding allows the homogenization of the two Ag and Pd sol id solutions whose composition changes to finally reach the initial Ag 50Pd50 composition. The defects as dislocations generated by the impac t conditions may be responsible for the reaction mechanism.