Thermal stability of a nanostructured aluminium alloy

The microstructural changes taking place in a hydrostatically extrusion-processed nanostructured aluminium alloy during annealing were evaluated quantitatively, by measuring the size and shape of the grains. It was found that the grain size is stable up to an annealing temperature of 300 °C. Within this temperature range, the microstructural evolution proceeds through the annihilation of dislocations in the interior of the grains. At higher annealing temperatures, the recovered grains begin to grow and the microstructure becomes more homogeneous in terms of the grain size. The possibilities of an improvement of alloy thermal stability are discussed.