Dynamic grain coarsening in creep of pure Cu at 0.42Tm after predeformation by ECAP

Microcrystalline Cu99.99 produced by equal channel angular pressing and static recrystallization was deformed in tensile and compressive creep at 573 K. Discontinuous coarsening of grains led to dramatic changes of creep rate. These reflect general hardening as the grains coarsen, superimposed by transient net softening when grain boundary migration activity peaks. The strength at the first minimum of creep rate is modeled by treating the material as a composite of subgrain-free and subgrain-containing grains with different recovery kinetics.