Low cycle fatigue behavior of precipitation-strengthened Cu-Cr-Zr contact wires

The low cycle fatigue behavior (Delta epsilon(t)/2 = 0.4-1.0%) of a Cu-Cr-Zr alloy strengthened with nanoscale precipitates has been tested at room temperature. The results showed that cyclic softening occurs under all Delta epsilon(t)/2 after cyclic hardening. However, the Cu-Cr-Zr alloy exhibited secondary cycle hardening after a brief softening at high Delta epsilon(t)/2 (0.8%, 1.0%). In strong contrast to the fatigue fracture surface at Delta epsilon(t)/2 = 0.4%, Delta epsilon(t)/2 = 1.0% was characterized by multiple fatigue sources and obvious fatigue striations. Moreover, a sawtooth-like feature formed and the fracture mode was mainly brittle with few regions of ductile aspects. Compared with the original characteristics, the microstructure after different values of Delta epsilon(t)/2( )was markedly different, and the dislocation density gradually increased with the increases of Delta epsilon(t)/2.