(西安理工大学 材料科学与工程学院，西安 710048)
摘 要: 应用微型电容储能焊机对厚度约35~45 μm的Fe-60%Cu(质量分数)合金急冷箔进行点焊连接，观察接头的组织形貌，分析接头的冷却速率和温度梯度及其与熔核组织及接头性能的相关性。结果表明：应用电容储能焊瞬间放电所产生的高能量可以实现急冷合金箔的连接，获得直径34 mm、高30 mm、形状较规则的扁球状熔核；接头冷却速率达106 K/s，熔核组织具有明显的快速凝固特征；熔核在快速凝固过程中产生液相分离，富Fe相的小液滴在温度梯度驱动的Marangoni对流作用下向熔核中心移动，并不断凝并长大，最终形成一种第二相向中心偏聚的组织结构；随着温度梯度的增大，富Fe相液滴的运动速度呈线性增大；点焊接头的剪切强度较高，达241 MPa。
关键字: 合金箔；储能焊；点焊接头；相分离；快速凝固
（School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048, China）
Abstract:The spot welding of rapidly solidified Fe-Cu alloy foils with 35−45 μm in thickness was conducted using a mini-type capacitor discharge welder. The microstructure of nugget was observed. The cooling rate and the temperature gradient of nugget were analyzed theoretically and the relationship between the microstructure and property of the joint was investigated. The results indicate that the capacitor discharge welding can realize the spot weld of rapidly solidified Fe-Cu alloy foils, and a regular oblate spheroid nugget with 34 mm in diameter and 30 mm in thickness forms. The cooling rate of nugget is up to106 K/s, and the microstructure of nugget is characterized by rapid solidification. The liquid separation takes place in micro nugget during rapid solidification. The Fe-rich droplets move toward the center of the nugget resulting from Marangoni migration driven by temperature gradient, leading to the formation of microstructure of second phase segregating in the nugget center. With increasing temperature gradient, the growth velocity of the droplets increases linearly. The shearing strength of the joint is up to 241 MPa.
Key words: alloy foil; capacitor discharge welding; spot weld joint; phase separation; rapid solidification
