An investigation of thermal stability of structure and mechanical properties of Al-0.5Mg–Sc ultrafine-grained aluminum alloys

Abstract

This paper presents the results of studying the thermal stability of the grain structure, mechanical properties, and specific electrical resistivity of the Al-0.5 wt%Mg-xSc ultrafine-grained (UFG) alloys with varying scandium content (x = 0, 0.2, 0.3, 0.4, and 0.5 wt.%). The alloys were produced by induction casting and Equal-Channel Angular Pressing (ECAP). The alloys with Sc concentration above 0.3 wt% contained submicron Al3Sc primary particles, the amount of which increased with increasing Sc concentration. The decomposition kinetics of the Al–Sc solid solution in the UFG alloys was determined by the diffusion intensity along the dislocation cores in the lattice as well as at the grain boundaries. High thermal stability of the UFG structure in the alloys was ensured by ECAP at 225 оC whereas the recrystallization onset temperature was 375 оC. The UFG alloys exhibited high plasticity at the room and elevated temperatures and good combination of strength and electrical conductivity.