Extended x-ray-absorption fine-structure studies on ball-milled powders of the immiscible system Cu-V.

Abstract

The extended x-ray-absorption fine structure (EXAFS) of mechanically alloyed ${\mathrm{Cu}}_{50}$${\mathrm{V}}_{50}$ and ${\mathrm{Cu}}_{30}$${\mathrm{V}}_{70}$, which were obtained from ball milling of a mixture of pure metallic copper and vanadium powders, has been studied. A significant change in the copper K x-ray-absorption spectra was observed as the milling time increased, while the basic oscillation pattern of the vanadium K EXAFS did not change so much. This indicates that a supersaturated solid solution is formed such that copper atoms enter into the bcc vanadium lattice in spite of their extremely limited dissolubility in the phase diagram. It was also observed that the destruction of the fcc structure of copper proceeds prior to the formation of the solid solution in the early stage of mechanical alloying.