Phase transitions in copper–silver alloys under high pressure torsion

Abstract

AbstractThe influence of high pressure torsion (HPT) on the formation and decomposition of solid solutions in the copper–silver system has been studied. The investigated Cu-8 wt.% Ag alloy was annealed at two different temperatures, 500 and 650°C, and quenched. The samples consisted of (Cu) solid solution in the matrix with (Ag) precipitates. During HPT a steady-state value of torsion torque was reached after about 1.5 anvil rotations. After HPT (5 anvil rotations) the composition of the (Cu) solid solution in both samples had become equal. In other words, the concentration of silver in the (Cu) matrix annealed at 650°C decreased and in the sample annealed at 500°C increased. Moreover, a similar process took place in (Ag) precipitates as well. The concentration of copper in (Ag) particles in the sample annealed at 650°C decreased and in the sample annealed at 500°C increased. Thus, the composition of (Cu) and (Ag) solid solutions reached at steady-state during HPT does not depend on that before HPT. The composition of the (Cu) and (Ag) solid solutions after HPT is as high as if the samples were annealed at a certain intermediate temperature about 600 ± 20°C.