Influence of magnesium additions on the low temperature recovery stages in neutron irradiated aluminium

Abstract

In order to investigate the interaction between interstitial defects and impurity atoms in aluminium, a series of dilute aluminium-magnesium alloys were neutron irradiated at 24K. The recovery of electrical resistivity shows that the addition of increasing magnesium concentrations decreases the high temperature part (32-55K) of stage I. The migration energy of a free interstitial has been found equal to 125+or-5 meV. Stage II (55-175K) is also modified by magnesium additions but two opposite effects are observed according to the temperature range. Below 100K, sub-stage II_A has a behaviour similar to that of stage I; its amplitude decreases with increasing magnesium content. This sub-stage appears to be the result of several recovery mechanisms which involve multiple interstitial defects. Inversely, above 100K, stage II_B, which does not exist in pure aluminium, appears and grows in importance for higher concentrations.