Internal friction study of the stress relaxation behavior in Cu–Ni–P alloys

The strain-amplitude dependence of internal friction in Cu–Ni–P alloys has been investigated to evaluate nondestructively the stress relaxation resistance. Annealing at 250 °C after cold rolling causes a suppression of the strain-amplitude dependence with increasing annealing time in the range between 10 and 104 s. It is revealed that the stress relaxation resistance linearly improves as the microplastic strain evaluated from the amplitude-dependent internal friction decreases.