Equimolar solid solutions of Ag-Cu and Co-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 micro-scopy and differential scanning calorimetry. Large mixing enthalpies (ΔH = 6·8 kJ g-atom-1 and ΔH = 4·8 kJ g-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.

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