Ultrafine-grained CuAg7Zr0.05 alloy with fully recrystallized microstructure

A CuAg7Zr0.05 alloy was processed by high-pressure torsion (HPT) for 10 revolutions, and subsequent annealing resulted in a fully recrystallized ultrafine-grained (UFG) microstructure. A minimum mean grain size of 117 nm was successfully achieved, which is quite uncommon via conventional deformation and annealing process. Tensile tests indicate that these recrystallized UFG specimens possess ultrahigh yield strength up to 917 MPa and notable ductility of 14%. However, the uniform elongation was sensitive to the grain size, and there was a sharp improvement when the grain size increased from 334 nm to 444 nm. Mechanisms for the sharp transition were explored.