Anelastic creep and recovery in a Mg-Al-Zn alloy

Large stress reductions during high temperature steady-state creep of polycrystalline materials lead to a period of ‘negative’ or ‘anelastic’ creep during which the specimen contracts although still subjected to a tensile stress. Stress-change experiments performed during the anelastic creep period of a Mg-6%Al-1%Zn alloy suggest that the rate-controlling mechanisms are essentially the same as those controlling normal forward creep, that is the growth of dislocation networks to produce individual dislocation link lengths sufficiently long to act as slip sources. It is shown that the network theory of Davies and Wilshire can account for all stress-reduction phenomena observed during forward creep.