| Summary: | The low-temperature α-CoSn3 intermetallic compound (IMC) doped with Ni is an important component at the interface between Sn-based solder and printed circuit boards, which largely controls the mechanical properties of solder joints. However, the structure and elastic properties of α-CoSn3 doped with Ni are not well understood. In this work, first-principle calculations and nano-indentation have been performed to explore the influences of additional Ni on elastic properties of α-CoSn3 IMC. By means of nano-indentation, the Young’s modulus and hardness were recorded for α-CoSn3 and α-(Co,Ni)Sn3 to be 149.9 ± 8.6 GPa and 6.14 ± 0.96 GPa, and 142.5 ± 7.6 GPa and 5.84 ± 0.76 GPa, respectively. Systematic works of first-principle calculations indicated that the doped Ni weakened the mechanical properties while strengthened the ductility and elastic anisotropy of α-CoSn3. The calculated electronic structures demonstrated that the bonding energies of α-CoSn3 were obviously decreased with the doping of Ni, which led to the degeneration of mechanical properties. Keywords: Intermetallic compound, Nano-indentation, First-principles calculations, Mechanical properties
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