A crystallographic orientation based model for describing the precipitation strengthening of stress-aged Al-Cu alloy

The effects of stress magnitude and crystallographic orientation on the mechanical properties of stress-aged Al-2Cu alloy single crystal specimens are investigated. The specimens with (1-, 1, 6) plane orientation were stress-aged under 0, 15, 40, and 60 MPa. Specimens with five different plane orientations ((1-, 2-, 6), (3, 1, 3), (1-, 3, 3), (1-, 1, 6), and (1-, 4-, 6)) were stress-aged under stress with the same magnitude of 40 MPa. The results of mechanical properties and TEM microstructure show that the yield stress of stress-aged specimens depends on the crystallographic orientation as well as the stress magnitude. A model based on crystallographic orientation describes the precipitation strengthening of stress-aged Al-2Cu alloy. The calculated yield stresses in the model fit well with the experimental observations. This model results not only provide important insight into solving the anisotropy problem attributed to precipitation strengthening, but also offer a benchmark for choosing the right range of stress in the manufacture of Al-Cu alloys.