A comparative study of fatigue properties of two face-centered-cubic metals

Fatigue tests were performed on two sets of specimens made of aluminum and nickel. The cyclic stress strain curve (CSSC) of aluminum exhibited a cyclic hardening response, in which the saturation stress increased with plastic strain amplitude, whereas the CSSC of nickel exhibited cyclic hardening in two stages: a stage at which saturation stress increases with plastic strain amplitudes and a second stage, which exhibits a semiplateau showing a slight increase in saturation stress with plastic strain amplitudes. Transmission electron microscopy (TEM) analysis of both materials showed that nickel contains elongated dislocations and persistent slip bands, while aluminum contains dislocation cells.