Impression creep behavior of a Cu–6Ni–2Mn–2Sn–2Al alloy

Abstract

The impression creep behavior of the aging-treated Cu–6Ni–2Mn–2Sn–2Al alloy and its variants with separate additions of 0.3 wt.% Cr and 0.3 wt.% Zr was investigated in the temperature range 695–795 K and under constant punch stress in the range 300–900 MPa. It was shown that simple theory, based on a steady-state power-law creep equation, has the capacity to describe the impression creep data satisfactorily. The average stress exponents of about 4 together with the activation energies of 194–196.9 kJ mol−1, which are close to 197 kJ mol−1 for lattice self diffusion of copper, suggests that in all of the tested alloys the operative creep mechanism is dislocation climb controlled by lattice diffusion. The creep resistance of the base material was better than that of the Cu–0.3Cr–0.1Ag alloy reported in the literature. Further enhancement in creep resistance was achieved by incorporating Cr and Zr into the base alloy. This was achieved by the precipitation of Cr-rich and Zr-rich particles in the Cu matrix of the Cr- and Zr-containing alloys, which act as dispersion strengtheners in the present alloys.