Effect of Ag Doping on Mechanical Properties of Cu6Sn5 Intermetallic Compounds

Cu6Sn5-xAg alloys (x = 0, 3, 6; %, mass fraction) were synthesized using Ag as a dopant through a high-temperature melting technique. The microstructure of the alloy was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and other equipment, while the hardness of the alloy was measured to investigate the impact of Ag addition on the structure and microstructure of the Cu6Sn5 intermetallic compound. This study explored the influence of varying Ag contents on the properties of Cu6Sn5 intermetallic compounds, with calculations based on first principles revealing the mechanical properties and density of states of eta '-Cu6Sn5 and its Ag-doped systems. The results indicated that Cu6Sn5-xAg alloys predominantly existed in three distinct forms, all exhibiting large masses without any impurities or precipitates. First-principle calculations demonstrated that Ag substitution in certain sites suppressed the anisotropy of the Young's modulus of Cu6Sn5, particularly in the Cu1, Cu3, Sn1, and Sn3 positions, while the effect was less significant at the Cu2, Cu4, and Sn2 sites. The introduction of Ag through doping enhanced the covalent bonding within the eta '-Cu6Sn5 structure, promoting the formation of a stable (Cu, Ag)(6)Sn-5 structure.