鋁合金/低碳鋼點(diǎn)焊界面反應(yīng)物生長機(jī)制

鋁合金/低碳鋼點(diǎn)焊界面反應(yīng)物生長機(jī)制Growth mechanism of reactants at spot welding interface between aluminum alloy and low carbon steel

采用電阻點(diǎn)焊對(duì)鋁合金與低碳鋼進(jìn)行焊接，分析了接合界面區(qū)反應(yīng)層形貌及分布等顯微組織特征。結(jié)果表明：在接合界面上觀察到反應(yīng)物層的生成，其厚度隨位置的變化而變化；界面反應(yīng)物是由靠近鋁合金側(cè)的反應(yīng)物為FeAl3和靠近鋼側(cè)反應(yīng)物為Fe2Al5構(gòu)成；FeAl3的生成歸結(jié)于其生成自由能較低，而Fe2Al5的生長主要因其結(jié)構(gòu)上在c軸方向存有大量Al原子空位而造成的各向異性擴(kuò)散。

Aluminum alloy and low carbon steel sheets were welded by resistance spot welding. The interfacial characterization was observed and analyzed. The results show that a reactant layer forms at the welding interface; its thickness varies with the position at the welding interface. A reactant layer consisting of Fe2Al5 adjacent to steel and FeAl3 adjacent to aluminum alloy forms in the welding interface. Low free energy of FeAl3 is considered to be the reason for its formation at the welding interface, whereas anisotropic diffusion, which resulted from large number of aluminum vacancies along the c-axis of the orthorhombic structure of Fe2Al5, is a reason for the growth of Fe2Al5.

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