Production of recrystallized nano-grains in a fine-grained Cu-Zn alloy

A fine-grained Cu-30% Zn alloy sheet was rolled at 77K to induce ultrafine mechanical twins. Subsequent annealing of the rolled alloy at temperatures up to 543K led to the uniform appearance of recrystallized ultrafine grains (UFGs), which contained numerous annealing twins. Average grain sizes of 150 similar to 300 nm were produced in this way. The formation of such UFGs during annealing is attributed to the high nucleus density associated with the fine initial grain size as well as to the high densities of mechanical twins and dislocations produced by cryorolling. The high driving force for recrystallization enabled the use of relatively low annealing temperatures, which limited the subsequent grain growth.