On the addition of precipitation- and work-hardening in an Al–Sc alloy

Specimens of Al–0.2 wt.% Sc were solution heat treated and subjected to precipitation heat treatment. Precipitation-hardening response depended on storage time after solution heat treatment. An underaged condition and an overaged condition with equal strengths were found. Transmission electron microscopy indicates that the dislocations pass the precipitates by shearing in the underaged condition, and not in the overaged conditions. Analyses of stress–strain curves show significant differences in work-hardening behaviour between the two conditions.