Breakdown of the power-law creep in a Class I Al-10 at % Zn alloy

The creep behaviour of Al-10 at% Zn at 573 K is divisible into three deformation regions; low stress region, intermediate stress region and high stress region. The creep characteristics of the low stress region and intermediate stress region are consistent with dislocation climb and viscous glide, respectively. In the high stress region, the stress exponent,n increases with stress, the activation energy is higher than those observed in the other two regions, the activation area is slightly decreasing with stress and the internal stress is almost negligible. Present analysis shows that these characteristics are consistent with the thermally-activated glide motion of dislocations as a rate controlling mechanism at high stresses.[/p]