Effect of deformation schedules and initial states on structure and properties of Cu–0.18% Zr alloy after high-pressure torsion and heating

Abstract

Structure, microhardness and electrical resistivity of the Cu–0.18% Zr alloy after high pressure torsion (HPT) were investigated for different initial states (hot-pressed, annealed, quenched) and deformation schedules. It is shown that HPT leads to formation of submicrocrystalline structure with the grain size of 200–250nm. Studying of electrical resistivity of the Cu–0.18% Zr alloy showed that during HPT it increases with increasing the strain in comparison with initial not deformed state. It can be connected with changes of grain and subgrain structure, and also with processes of dissolution of particles of the second phase Cu5Zr during deformation. Decreasing of electrical resistivity values of Cu–0.18% Zr alloy after HPT during heating in the temperatures range of 250–400°C and preservation or increase of microhardness values in this temperature interval reveal aging processes with allocation of Cu5Zr particles and confirm the fact of partial supersaturation of solid solution of copper with zirconium during deformation. Аpplication of quenching, HPT and subsequent aging allows to achieve the maximum strengthening of the alloy.