Comparison of the effects of Mg and Ga additions on defect production and recovery in aluminium, neutron-irradiated at 4.6K

Abstract

The influence of foreign atoms on the defect production rate, during reactor irradiation of aluminium at 4.6 K, has been studied by electrical resistivity measurements on a series of dilute Al(Mg) and Al(Ga) alloys. In high purity aluminium, the decrease of resistivity damage rate with increasing defect resistivity may be interpreted in terms of spontaneous recombination processes with a high incidence of dynamic effects. The presence of the addition element produces an increase of the low-dose damage rate and, for the most concentrated alloys, of the saturation value of the resistivity increment. These effects appear to be due to both deviations from Matthiessen's rule and enhanced defect production rates. During subsequent annealing, the alloys exhibit a decreased recovery with respect to the pure metal in the intrinsic stages I and IIA, and increases of recovery in the temperature ranges corresponding to stages IIB, III and III'. In the Al(Mg) alloys the extra recovery stages occur at slightly higher temperatures than in the Al(Ga) alloys; this indicates a stronger interaction of Mg atoms with interstitial defects and should be related to the larger size-effect of this element in the aluminium lattice.