Abstract:
Nano- and submicron-structured aluminium was produced by equal channel angular
extrusion with a total strain of ̴17. Large residual stress and strain energy were built up in the
extruded metal and subsequent heat treatments were applied to investigate the stability of the
nanostructures. X-ray diffractometry and transmission electron microscopy were performed to
evaluate the microstructural changes in the nanograin metal. It was found that the nanostructures
remained stable at temperatures up to 250°C. Above 250°C, changes in the major x-ray peak
reflections became evident, suggesting substantial grain growth had occurred. Electron microscopy
confirmed that at low annealing temperatures, the fine grain structures were stable and indeed
became more equiaxed and well defined.
