Effects of thermal treatments on the residual stress and micro-yield strength of Al2O3 dispersion strengthened copper alloy

The microstructure, residual stress, and mechanical properties of a Cu-0.05wt%Al2O3 dispersion strengthened alloy in different treatment states were investigated. The alloy was cold forged with a reduction of 60%, followed by either normal annealing or creep annealing at 600 degrees C for 6 h. Compared with the cold forged alloy, the micro-yield strength and the residual stress of the creep annealed alloy were reduced by 8.2% and 80.3%, respectively. The significant decrease in residual stress after creep annealing could result from the elimination of voids and defects and the reduction of dislocation density in the sub-grains during heat treatment. The high micro-yield strength of the creep annealed alloy can be attributed to the well dispersed nano Al2O3 particles effectively pinning the sub-grain boundaries at the elevated temperature. (C) 2018 Elsevier B.V. All rights reserved.