Low-cycle fatigue properties of ultrafine-grained zinc–22 wt.% aluminum alloy during room-temperature superplastic flow

Low-cycle fatigue behavior during room-temperature superplastic flow was investigated for ultrafine-grained Zn–22 wt.%Al alloy. This alloy exhibited a longer fatigue life and a lower crack propagation rate than other materials at high strain amplitudes above ±5%. In addition, many cavities and secondary cracks were observed near the tips of cracks. These are probably responsible for the apparent reduction in the crack propagation rate and the long fatigue lifetime of this alloy.