为实现镁合金AZ31B与铜的可靠连接, 采用铝作为中间层, 在450 ℃保温30～120 min的条件下进行扩散钎焊试验, 研究了保温时间对接头组织、显微硬度和剪切强度的影响。结果表明：保温时间为30 min时, 接头无法实现过渡液相扩散连接; 当保温时间为60 min时, 铝中间层完全溶解, 接头中形成了宽约150 μm的扩散区, 从镁合金侧到铜侧, 扩散区的组织依次为镁基固溶体、共晶组织和Cu3Al2Mg2金属间化合物; 保温不同时间后, 从扩散区的镁合金侧到铜侧, 显微硬度均呈阶梯式升高; 随着保温时间延长, 铜侧过渡层的显微硬度显著增加, 接头的剪切强度先增大后降低, 并在保温90 min后达到最高, 为68.2 MPa; 断裂发生在靠近铜侧的扩散区。

To achieve reliable bonding between AZ31B magnesium alloy and copper, diffusion bonding tests for AZ31B magesium alloy and Cu with Al interlayer were carried out at 450 ℃ for 30-120 min, and the effects of holding time on microstructure, microhardness and shear strength of the joint were studied. The results show that the transient liquid phase bonding for the joint could not be achieved when holding time was 30 min. When holding time was 60 min, Al interlayer completely dissolved, and a diffusion zone with width about 150 μm formed in the joint, the microstructures of diffusion zone were magnesium-based solid solution, eutectic structure and Cu3Al2Mg2 intermetallic compound, in turn, from magnesium alloy side to Cu side. After holding for different times, microhardness increased in a stepped form from magnesium alloy side to Cu side in diffussion zone. With the increase of holding time, microhardness of Cu side in fussion zone increased remarkably, shear strength of the joint increased firstly and then decreased, and up to the maximun value of 68.2 MPa when holding time was 90 min. Fracture occurred at diffusion zone near Cu side.