Mechanical alloying of immiscible elements: Ag-Fe contrasted with Cu-Fe

Extended x-ray-absorption fine-structure analysis demonstrates that the Cu-Fe and Ag-Fe systems, both immiscible in equilibrium, exhibit contrasting alloying behavior when subjected to mechanical milling. While Cu-Fe undergoes atomic-level alloying forming solid solutions, Ag-Fe remains largely unreacted. The alloying behavior observed is explained based on a model for a dynamic system, combining both the effects of externally driven mixing and thermal evolution under the thermodynamic driving force prevailing in a ball-milled mixture.