Phase transitions during high pressure torsion of CuCo alloys

•Severe plastic deformation by high-pressure torsion (HPT) changes the composition of phases in the Cu–4.9 wt% Co alloy.•The fully homogenized solid solution partly decomposed after HPT.•The Co particles precipitated from the matrix partly dissolved under the same HPT processing.•The steady-state composition of the matrix is Cu–2.5 wt% Co and does not depend on the starting state.

High-pressure torsion of Cu–4.9 wt% Co alloy has been studied, with Co fully dissolved in the Cu matrix and fully precipitated from the matrix. A steady-state was reached in both samples after 1–2 anvil rotations. The solid solution in the first sample partly decomposed. The Co precipitates in the second sample partly dissolved in the matrix. In both cases the Co precipitates surrounded by the Cu-based solid solution with about 2.5 wt% Co were formed.

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