Precipitation behavior of stress-aged Al-Cu-Mg-Ag alloy bicrystals

The precipitation behavior of Al-Cu-Mg-Ag alloy bicrystals with (1-1 2) and (-3 1 3) orientations was investigated under stress conditions of 0 MPa, 50 MPa, and 100 MPa during aging at 180 degrees C for 53 h. The results indicate that the precipitates formed within the matrix were 52, S, and 0 ' phases. Considering the crystallographic anisotropy, orientations of stress-induced precipitates, and the interaction with stress-induced dislocations, we conducted a quantitative statistical analysis to evaluate the size and distribution of the precipitate phases. Calculations based on the precipitation strengthening model clearly demonstrate that stress aging treatment significantly enhanced the precipitation strengthening effect, with the 52 phase contributing over 90 % to this enhancement. Additionally, intragranular regions exhibited a higher precipitation strengthening effect compared to the regions adjacent to grain boundaries. However, with increasing stress, the difference in precipitation strengthening contributions between intragranular regions and those near grain boundaries progressively lessened. Stress loading further prompted grain boundary segregation, a phenomenon that intensified under higher stress levels, thereby influencing the distribution and volume fraction of the 52 phase to a certain degree. This investigation provides a reference for fabricating high-performance Al-Cu-Mg-Ag alloys through texture optimization and stress aging treatments.