Microstructural investigations into the low cycle fatigue deformation of a Cu-Cr-Zr-Ti alloy

Fully reversed axial strain controlled low cycle fatigue behaviour of a Cu-Cr-Zr-Ti alloy was investigated in the solution-annealed condition. Temperatures in the range, 300-900 K were employed for the tests which were carried out at a constant strain rate of 3×10−3 s−1. The cyclic stress response was found to vary as a function of the test temperature, with a strong secondary hardening occurring in the range, 673-773 K which was associated with the formation of Cr-rich precipitates. Prior thermal ageing served to shift the cyclic stress response upwards and caused disappearance of the secondary hardening regime. Further, the serrations in the stress-strain hysteresis loops observed at the test temperature of 900 K remained absent in samples tested after the prior ageing treatment. The results are explained on the basis of microstructural observations.