Formation of metastable solid solutions by mechanical alloying of immiscible Ag and Bi

This work investigates the effects of the Vickers micro-hardness of Ag powders on the alloying process undergone by Ag90Bi10 powder mixtures submitted to ball milling. The transformation kinetics has been studied by quantitative X-ray diffraction. The experimental findings indicate that Bi gradually dissolves into Ag, finally forming a crystalline solid solution in which thermodynamic solubility limits are largely exceeded. It is shown that the rate of Bi dissolution, and the solubility degree, decrease as the Vickers micro-hardness of Ag powders increases.