Microstructure and properties of Ta1/Ta₈Ni₃₀Cr₂₀Cu₄₂/0Cr18Ni9 energy storage welding joint

In order to solve the problem of brittle intermetallic compounds in energy storage welding joint due to the great difference of physical and chemical properties between tantalum and steel, Ta₂₀Fe₂₀Ni₂₀Cr₂₀Cu₂₀ alloy with equal molar ratio was used as the target composition of nugget according to the high entropy technology of nugget metal, Ta₈Ni₃₀Cr₂₀Cu₄₂ intermediate layer alloy was obtained according to the fusion ratio of two base metals in welding process, which was used for Ta1/0Cr18Ni9 energy storage welding connection. The results show that the high entropy alloying of nugget metal can effectively inhibit the formation of brittle intermetallic compounds in nugget. The morphology of Ta1/Ta₈Ni₃₀Cr₂₀Cu₄₂/0Cr18Ni9 energy storage welding joint is complete, and the nugget is regular cup-shaped, with a length of about 0.6 mm, and the overall shift to the steel side. The structure of nugget is mainly composed of simple FCC solid solution and a small amount of BCC solid solution. The solidification structure in the center of nugget is characterized by fine equiaxed grains. Columnar grains grow parallel to the fusion zone between the nugget and the base metal on both sides. Under the conditions of U = 1 000 V, C = 500 μF, F = 30 N, the average shear strength of the joint reaches 372 MPa.