Influence of Aging Temperature on Precipitation Kinetics, Morphology and Hardening Behavior of Al-7475 Alloy

In this research, the precipitation hardening behavior of Al-7475 alloy is investigated by a comprehensive experimental study on the relationship between thermal aging and evaluation of the kinetics and hardening properties of the alloy. The investigation was carried out using X-ray diffraction analysis (XRD), differential scanning calorimetry, scanning and transmission electron microscopy investigations and Vickers hardness (HV) test. The XRD results show that increasing the aging temperature, from 273 to 620K, enhances the coarsening and evolution of precipitates which leads to an increase in the particle size. The thermal analysis shows the precipitation kinetics of the observed phases such as eta ', T ', and eta, based on the correlation between migration and diffusion of spread atoms in the Al matrix. In addition, the TEM micrographs indicate that needle-shaped precipitates distinguish the development of eta ' and/or T '- precipitates which at most contribute to the material strengthening. Moreover, the reaction order values of eta ' and eta-precipitate nucleation indicate that the developed phases are radially grown.