Primary creep and anelastic behaviour of aluminium at low strains and temperatures below 0-45T(m)

Using highly sensitive equipment for the measurement of small shear stains up to 1.5 x 10(-4) and their variation with time, the form of the primary creep curves for aluminium at low stresses has been determined. The extent and rate of recovery of these strains has also been measured to establish the pattern of anelastic behaviour, and best fit equations are presented. A unique activation enthalpy could not be identified for anelastic recovery, but a value for the activation enthalpy comparable with grain boundary or dislocation pipe diffusion was derived from primary creep when the strain exceeded 10(-5). The ratio of the anelastic recovery strain to the forward creep strain decreased logarithmically with time over most of its range, but reached a limiting value that was dependent on the forward creep stain. (C) 1996 The Institute of Materials.