Metallurgical and mechanical properties of continuous drive friction welded copper/alumina dissimilar joints
Metallurgical and mechanical properties of continuous drive friction welded copper/alumina dissimilar joints
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DOI：
10.1016/j.matdes.2017.04.093
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发表时间：
2017-08
影响因子：
8.4
通讯作者：
Peng Li;Jinglong Li;Honggang Dong;Cheng-zhong Ji
中科院分区：
文献类型：
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作者：
Peng Li;Jinglong Li;Honggang Dong;Cheng-zhong Ji
焊接和应力集中是影响铜/铝异种接头工程应用的主要问题。采用2.5mm厚的AA 1100铝合金作为中间层，进行了铜与氧化铝的连续驱动摩擦焊。研究了摩擦压力和摩擦时间对接头抗拉强度的影响，分析了界面组织演变和断口形貌。在氧化铝/铝和铝/铜界面处发生了明显的相互扩散，增强了润湿性并提供了冶金结合。由于焊接过程中的热力耦合作用，在氧化铝基体中形成了微裂纹。随着摩擦压力的增加和摩擦时间的延长，拉伸强度先增加后下降，达到峰值35 MPa。确定了最佳工艺参数为摩擦压力12 MPa，摩擦时间12 s。所有样品在铝/氧化铝界面处失效，在氧化铝基底上留下凹坑结构。纯铝中间层的应用是获得良好的铜/氧化铝接头的必要条件，通过减少应力集中和润湿氧化铝，最佳的残余铝层厚度约为0.47 mm。摩擦界面由氧化铝/铝过渡到内塑化铝层，再过渡到铝/铜，直至焊接过程结束。
Wettability and stress concentration are the main challenges affecting the engineering application of copper/alumina dissimilar joints. In this paper, continuous drive friction welding of copper to alumina was conducted using 2.5 mm thick AA1100 aluminum as interlayer. The effects of friction pressure and friction time on the tensile strength of joints were evaluated, and the interface microstructure evolution and fracture morphologies were also analyzed. Obvious mutual diffusion occurred at the alumina/aluminum and aluminum/copper interfaces, enhancing wettability and proving metallurgical bonding. Microcracks formed in alumina base due to thermo-mechanical coupling effect in welding. As increasing friction pressure and friction time, the tensile strength increased till reaching a peak value of 35 MPa, and then decreased. The optimized parameters were determined as friction pressure of 12 MPa and friction time of 12 s. All samples failed at the aluminum/alumina interface, leaving a pit structure on alumina base. The application of pure aluminum interlayer is essential to obtain sound copper/alumina joints by diminishing stress concentration and wetting alumina, and the optimized residual aluminum layer is about 0.47 mm thick. The friction interface transferred from alumina/aluminum to inner plasticized aluminum layer, and then moved to aluminum/copper till the welding process finished.