Reduction of grain size in metals and metal mixtures processed by ball milling

This study focuses on the microstructural refinement induced by ball milling in individual metals and Cu-based metal mixtures. A phenomenological model is developed to rationalize the kinetics of grain size reduction. A discontinuous change of the average grain size is predicted to occur in very small powder volumes during each collision. The final average grain size and the rate of grain size reduction are shown to vary with the composition depending on the difference in hardness between the metals.