Ta1/Ta8Ni30Cr20Cu42/0Cr18Ni9储能焊接头组织与性能

针对钽与钢之间因物化性能差异大，储能焊接头易产生脆性金属间化合物等问题，依据熔核金属高熵化技术思路，以等摩尔比的Ta₂₀Fe₂₀Ni₂₀Cr₂₀Cu₂₀合金为熔核目标成分，依据焊接过程两种母材熔合比折合得到Ta₈Ni₃₀Cr₂₀Cu₄₂中间层合金，将其用于Ta1/0Cr18Ni9的储能焊连接. 结果表明，熔核金属的高熵合金化可有效地抑制熔核中脆性金属间化合物的形成，Ta1/Ta₈Ni₃₀Cr₂₀Cu₄₂/0Cr18Ni9储能焊接头形貌完整，熔核呈规则的杯形，长径约0.6 mm，整体向钢侧发生了偏移. 熔核组织以简单FCC固溶体为主相，兼有少量BCC固溶体. 熔核中心凝固组织以细小的等轴晶为特征，熔核与两侧母材熔合区则形成了平行生长的柱状晶，熔核区与母材结合良好. 在焊接电压1 000 V，电容500 μF，电极力30 N工艺条件下，接头平均抗剪强度372 MPa.

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.