Effects of Ag addition on mechanical properties and microstructures of Al-8Cu-0.5Mg alloy

The mechanical properties and microstructures of Al-8Cu-0.5Mg alloy with and without Ag addition were studied at both room- and elevated-temperatures. The results show that the alloy with Ag is strengthened by a homogeneous distribution of coexistent theta' and Omega precipitates on the matrix (00 1) and (111) planes, respectively, whereas the alloy without Ag by theta' precipitates only. The small size and high volume fraction of theta' and Omega precipitates in the Ag-containing alloy improve the tensile strength and yield strength, especially those at the elevated temperatures. However, it is also responsible for the decrease in elongation, compared with the alloy without Ag, which is due to the microcracks initiated from the inherent incompatibility between the particles and the Al matrix during deformation.