Ta1/0Cr18Ni9薄板储能焊熔核高熵化机理

High entropy mechanism of nugget in Ta1/0Cr18Ni9 sheetenergy storage welding

针对钽与钢之间物化性质差异大,焊接时易产生脆性金属间化合物而导致熔焊接头性能低下及裂纹等问题,按照熔核金属高熵化技术思路,利用基于密度泛函理论的热力学第一性原理设计出新型中间层合金Ta20Fe20Ni20Cr20Co20,结合熔合比得到适用于钽/钢储能焊中间层合金成分为Ta7Ni32Cr19Co42.采用真空电弧炉熔制纽扣合金锭,继而使用单辊急冷法制备出中间合金箔材,将其用于Ta1/0Cr18Ni9薄板的储能焊连接.结果表明,在储能焊条件下,Ta1/Ta7Ni32Cr19Co42/0Cr18Ni9搭接接头形成形貌规则、完整,长径约0.8 mm的扁球形熔核,熔核整体向钢侧发生了偏移.熔核组织由简单的FCC固溶体组成,无金属间化合物析出,具有典型的高熵合金特征,实现了熔核金属高熵化.在焊接电压1000 V,电容500μF,电极压力30 N下,Ta1/Ta7Ni32Cr19Co42/0Cr18Ni9储能焊接头平均强度可达到395 MPa.

In this paper,in view of the difference of physical and chemical properties between tantalum and steel,which is easy to produce brittle intermetallic compounds during welding,resulting in poor performance and cracks of fusion welded joints.According to the idea of high entropy technology of nugget metal, a new type of interlayer alloyTa20Fe20Ni20Cr20Co20 was designed based on the firstprinciples of thermodynamics based on density functionaltheory. Combined with fusion ratio, the composition ofintermediate layer alloy suitable for tantalum/steel energystorage welding is Ta7Ni32Cr19Co42. The button alloy ingotwas melted by vacuum arc furnace, and then the middle alloyfoil was prepared by single roll quenching method, which wasused for energy storage welding connection of Ta1/0Cr18Ni9sheet. The results show that under the condition of energystorage welding, Ta1/Ta7Ni32Cr19Co42/0Cr18Ni9 lap joint hasformed a flat spherical nugget with regular and completemorphology and about 0.8 mm long diameter, and the nuggethas shifted to the steel side as a whole.The nugget structureconsists of simple FCC solid solution and no intermetalliccompound precipitation. It has typical characteristics of highentropy alloy and realizes high entropy of nugget metal. Theaverage strength of Ta/Ta7Ni32Cr19Co42/0Cr18Ni9 energystorage welding joint can reach 395 MPa under the weldingvoltage of 1 000 V, capacitance of 500 μF and electrodepressure of 30 N.