Formation of nano-phase Co3Fe7 intermetallic and its strengthening in Au80Sn20/CrMnFeCoNi solder interface

As one of the High entropy alloys, CrMnFeCoNi shows excellent mechanical properties. It is of great value to explore the joining behavior of CrMnFeCoNi in order to expand its application fields. In this paper, we have fabricated the Au80Sn20/CrMnFeCoNi solder joint using vacuum soldering. The results indicate that Au80Sn20 eutectic alloy wets CrMnFeCoNi high entropy alloy well. Vickers hardness of the intermetallic compounds (IMCs) is about 300HV, higher than Au80Sn20 solder; the shear strength of solder joint reaches 67.52 MPa, 1.5–2 times stronger than that soldering with Kovar alloy and pure nickel. The distribution of novel nanoscale Co3Fe7 particles in the IMCs layer significantly enhances the shear strength of solder joint. The results motivate a multi-elements strategy to enhance mechanical performance of joints, thus showing great potential in industrial application.