Electron-microscopy investigation on nanocrystal formation in pure Fe and carbon steel during ball milling

Investigations on ball milled pure iron and Fe–0.89C spheroidite alloy powders indicated that the formation of nanoscaled dislocation cells and/or subgrain boundaries is responsible for the grain refinement to nanocrystals. The possible recovery and/or recrystallization due to adiabatic heating induced by high-strain rate is suggested to aid this process.