Stress-driven grain refinement in a microstructurally stable nanocrystalline binary alloy

Deformation-induced grain-growth in nanocrystalline materials is a widely-reported phenomenon that has been attributed to grain boundary (GB) processes. In this paper, we report on the opposite phenomenon, wherein stable (NC) Cu-Ta alloy undergoes further refinement of nano-grains during severe plastic deformation (SPD). SPD up 250% results significant grain-size reduction despite 350°C increase temperature caused by process. Experiments and atomistic-simulations show unexpected grain-refinement direct result well-dispersed Ta-nanoclusters throughout centers along GBs acting as kinetic-pinning agents suppressing GB processes occur recrystallization.