X-RAY-ABSORPTION SPECTROSCOPY AND DIFFRACTION STUDY OF MISCIBLE AND IMMISCIBLE BINARY METALLIC SYSTEMS PREPARED BY BALL-MILLING

A series of copper-based alloys (Cu-Ti, Cu-V, Cu-Mn, Cu-Co of equiatomic composition) were obtained by ball milling under a protective atmosphere with the aim of exploring the effect of milling on systems showing very different miscibilities in the solid state. The alloys were studied by means of X-ray spectroscopy (EXAFS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The mechanical treatment produces an amorphous phase in Cu-Ti. The other systems, displaying a positive heat of mixing, cannot be amorphized, although enhanced reactivity leads to the formation of supersaturated solid solutions. The effect of milling time has been studied on Cu50V50 following the increase in lattice parameters of both fcc and bcc solutions. The fragmentation of the crystallites to a size as low as 300 angstrom represents a necessary condition for the solid state reaction in Cu50V50.