Effect of creep annealing on the dimensional stability of dispersion strengthened copper alloy

Highlights: • Creep annealing (CA) improves dimensional stability of ADSC alloy dramatically. • CA reduces residual stress while increases micro-yield strength in treated alloy. • Residual stress reduction is mainly due to the decrease of dislocation density. • Micro-yield strength increases with the reduction of pores in CA treated alloy. -- Abstract: This study aims to enhance the dimensional stability of alumina dispersion strength copper alloy via creep annealing treatment. The microstructure, residual stress and micro-yield strength of alloys after different treatments were investigated. During creep annealing, the residual stress in the alloy was dramatically reduced due to the decrease of dislocation density. The nano-Al₂O₃ particles in the alloy did not coarsen or agglomerate during the high temperature treatment and retarded the growth of subgrains effectively, which played important roles in high micro-yield strength of creep annealed alloy. The pores were effectively reduced by the creep deformation during creep annealing, resulting in a more uniform residual stress distribution and an increase in micro-yield strength. Compared with extruded alloy, the residual stress of alloy creep annealed at 950 °C for 12 h was reduced by 88%, while the micro-yield strength increased by 9.7%, leading to a significant enhancement in dimensional stability of the alloy.