Microstructure evolution and strength degradation mechanisms of high-strength Al–Fe wire

Abstract

The strengthening mechanisms and the strength degradation behaviors of the high-strength Al–Fe wire were investigated in this study. The dispersed nano-scale precipitates, the texture and the fine grains in the radial section of the Al–Fe wire are the three main strengthening factors, i.e., precipitation strengthening, texture strengthening and grain-boundary strengthening. Besides, during the annealing process, the strength degradation behaviors of the Al–Fe wires due to the coarsening of precipitates and grains as well as the texture evolution were quantitatively calculated. Finally, the strength degradation mechanisms were divided into three stages by the annealing temperatures. In stage I (0–90 °C), the slight decrease of strength is attributed to the recovery of defects including vacancies and dislocations. In stage II (90–200 °C), the loss of strength is mainly caused by the coarsening of precipitates leading to a decrease of precipitation strengthening. In stage III (200–300 °C), the grain growth is responsible for the strength degradation of the Al–Fe wire. Besides, the thermo-stability of grain increases to 150 °C in the Al–Fe wire due to the precipitates formed at the grain boundaries.