Effects of Ga Content on Microstructure Evolution and Mechanical Response of Heterostructured Dual-Phase Ag-49Cu Alloys

Dual-phase heterostructured metals have excellent mechanical properties. This study systematically evaluated the impact of varying Ga concentrations on the microstructural evolution and mechanical response of dual-phase heterostructured Ag-49 wt.%Cu-xGa (x = 0, 5, 7, and 10 wt.%) alloys. The study utilized scanning electron microscopy (SEM) and nanoindentation experiments to analyze the structure evolution and hardness changes in Ag-Cu-Ga alloys. The results revealed that the volume fraction of the hard domains (Cu-rich phases) and the hardness increased as the Ga content increased. This increase in Ga content led to a greater degree of mechanical incompatibility between the soft and hard domains, ultimately enhancing the mechanical properties of Ag-Cu-Ga alloys. Through the implementation of a loading–unloading–reloading (LUR) test, it was shown that the Ag-49Cu-7Ga specimens exhibited higher levels of hetero-deformation-induced (HDI) stresses compared to the Ag-49Cu specimens that did not contain Ga elements. This difference can be attributed to the solid solution strengthening effect of Ga. Through the use of digital imaging technique (DIC), it has been discovered that the introduction of Ga element into the Ag-Cu-Ga specimen results in the formation of dispersed strain bands on the surface. These strain bands effectively absorb and distribute the applied strains, resulting in the Ag-49Cu-7Ga specimen exhibiting both high strength and good plasticity.