Effect of low-temperature annealing on the creep of 1570 aluminum alloy

The effect of preliminary low-temperature annealing on the creep of a submicrocrystalline 1570 aluminum alloy fabricated by severe plastic deformation is studied. The creep rate is found to increase with the annealing time, but long-term annealing for 4 h decreases the creep rate to the value characteristic of the alloy not subjected to preliminary annealing. The increase in the creep rate of the alloy subjected to preliminary annealing is likely to be caused by an increase in the nonequilibrium excess volume in grain boundaries as a result of the dissolution of grain-boundary nanopores upon annealing and, hence, by an increase in the grain-boundary diffusion rate and the grain-boundary sliding rate.