Mechanical alloying of immiscible elements: Experimental results on Ag‒Cu and Co‒Cu

Abstract

Abstract Equimolar solid solutions of Ag[sbnd]Cu and Co[sbnd]Cu were prepared by mechanical milling of the elements. The structure and the thermodynamic properties of the resulting phases were analysed by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Large mixing enthalpies (ΔH = 6–8kJg-atom−1 and ΔH = 4–8kJg-atom−1 for Ag-Cu and Co-Cu respectively) were measured in the alloyed phases. It is clear that the solid solution forms through a process of grain refinement down to the nanometre scale and is assisted by an atomic-scale dissolution. The possible role played by coherent interfaces in substantially increasing the energy of the solid solutions is discussed.