Investigation of the recrystallization of low temperature deformed highly pure types of aluminium

Abstract

The energy release of aluminium samples deformed by torsion under liquid nitrogen, were studied during heating up in a low temperature calorimeter. Complementary measurements of the electrical residual resistance, the flow stress and hardness, as well as optical and electron microscopic structural studies, and X-ray texture examination were carried out. Calorimetrically two reaction maxima were observed. While the maximum at the higher temperature correlates with the change from “hard” (deformed) to “soft” (recrystallized), the low temperature reaction does not affect the mechanical parameters. It may be associated with the recovery of vacancies. For the high temperature region the following holds: the stored energy and the transformation temperature clearly depend on purity, degree of deformation and deformation in temperature. The reaction rate follows an Arrhenius law with an activation energy averaging 73 kJ/mol. From the results, we conclude that during the high temperature peak essentially primary recrystallization occurs.