(西安理工大學 材料科學與工程學院，西安 710048)
摘 要: 應用微型電容儲能焊機對厚度約35~45 μm的Fe-60%Cu(質量分數(shù))合金急冷箔進行點焊連接，觀察接頭的組織形貌，分析接頭的冷卻速率和溫度梯度及其與熔核組織及接頭性能的相關性。結果表明：應用電容儲能焊瞬間放電所產(chǎn)生的高能量可以實現(xiàn)急冷合金箔的連接，獲得直徑34 mm、高30 mm、形狀較規(guī)則的扁球狀熔核；接頭冷卻速率達106 K/s，熔核組織具有明顯的快速凝固特征；熔核在快速凝固過程中產(chǎn)生液相分離，富Fe相的小液滴在溫度梯度驅動的Marangoni對流作用下向熔核中心移動，并不斷凝并長大，最終形成一種第二相向中心偏聚的組織結構；隨著溫度梯度的增大，富Fe相液滴的運動速度呈線性增大；點焊接頭的剪切強度較高，達241 MPa。
關鍵字: 合金箔；儲能焊；點焊接頭；相分離；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
