铝/镁复合板电致塑性连接界面接合机制研究

Cladding aluminum on a magnesium alloy plate provides an effective way to improve the plate’s toughness and corrosion resistance, thus broadening its applications. In this project, an innovative continuous rolling technology assisted with high-frequency alternating & low-frequency pulsed currents is proposed to fabricate such Al/Mg alloy clad plates. The focus of this study is on the bonding mechanism of electro-plastic bonding interface. The proximity effect and skin effect of high-frequency alternating current at the Al/Mg bonding interface will be investigated along with the discharge phenomena and oxide film removing mechanism at the heterogeneous interface. Joule heating and electro-plastic effect in contact zones and plastic deformation bonding mechanism in pressurized regions will also be studied. Effects of currents on dislocation motion, texture behavior, and plastic flow stress will be examined, as well as low-frequency pulsed current’s influence on bonding interfacial morphology. The effect of synergy between the applied currents on plastic deformation behaviors at the Al/Mg bonding interface will be analyzed. A mathematical model will be developed to elucidate the thermodynamic and kinetic behaviors at the heterogeneous bonding interface under the electro-plastic effect, thus to further understand the interfacial bonding mechanism of the Al/Mg clad plate. The microstructure, strength, and other macroscopic mechanical properties of the bonding interface of the Al/Mg clad plate will also be characterized. This proposed research can enrich the laminated clad plate fabrication theory and the bonding technology of heterogeneous metals, providing a theoretical basis for the industrialization of metal-based clad plates.

覆铝镁基复合板材是改善镁合金强韧性和耐蚀性，拓展镁合金应用的有效途径。本项目提出“高频交流+低频脉冲”电流作用实现铝/镁层状复合板材的连续轧制连接技术，重点研究其电致塑性连接界面接合机制。探索高频交流电在铝/镁连接表面的邻近效应和趋肤效应，异质界面会合区的放电现象和双侧氧化膜破碎去除机制；探究接触区的焦耳热效应、电致塑性效应及压力区的塑性连接机理。揭示复合电流作用对铝/镁材料的位错运动、织构行为及塑性流变应力的影响机理，低频脉冲电流对连接界面形貌的影响规律；剖析铝/镁连接界面的协调塑性变形行为，阐释其对界面接合的重要贡献。创建数值模型阐明电致塑性效应作用下异质连接界面的热力学和动力学行为，进而揭示铝/镁复合板连接界面的微观接合机制。进一步表征连续轧制铝/镁复合板材界面微观组织、接合强度和宏观力学性能。该研究将丰富层状复合板的制造理论和异质材料连接技术，为金属基复合板材产业化提供理论基础。

为了改善镁合金材料强韧性和耐蚀性的不足，进而拓宽镁合金材料的应用领域。本项目提出了采用“高频交流+低频脉冲”电流辅助轧制铝/镁层状复合板材的连接技术，重点研究了连接界面的接合机制。.本项目搭建了电流辅助轧制铝/镁合金复合板的电流加载装置，采用数值模拟方法阐释了不同电流加载位置、加载方式，复合板连接界面及横截面的电流密度和温度场分布。.采用脉冲电流辅助轧制在大气环境下实现了铝/镁合金复合板的制备。研究发现：与传统热轧复合对比，复合板宏观形貌呈现平直，镁合金板材侧无明显边裂；复合板横截面的连接界面处有明显的局部母材熔融金属挤出的金属液珠，连接界面的微观形貌呈现明显的“齿状”结构，抗拉强度达到260 MPa，界面剪切强度最高达到27.87 MPa。.对铝/镁合金复合板连接界面的结合机理分析，可归纳为：镁/铝连接界面的局部高温导致界面微区部分母材金属熔化和原子互扩散的冶金结合机理。分析其原因一方面是异种金属连接界面待复合微区的局部接触电阻增大，导致连接界面局部高温；另一方面是高频脉冲电流在待连接界面微区的集肤和邻近效应导致的连接界面局部温度升高并达到Mg-Al相图共晶点以上。.本项目提出的“高频+低频”脉冲电流辅助轧制方法是一种有效地制备高性能铝/镁合金复合板的方法，为镁合金材料更高使用要求的安全服役提供了一定的技术支持与可靠数据参考。.共发表相关学术论文13篇，申请国家发明专利5项，已授权3项。