镁合金/铜双金属焊接件兼顾Mg、Cu的优异性能，在工程结构中，具有广阔的应用前景。但镁和铜的熔点相差较大，镁的活性强，物理、冶金相容性差，接头强度不足。因此，镁合金/铜异种金属接头的应用受到限制。根据本课题组之前的研究，本文以30 m的Al箔、Zn箔作为中间层，采用真空扩散钎焊炉，对AZ31B镁合金/T2纯Cu进行扩散钎焊实验，通过SEM、EDS、XRD、显微硬度、电子万能拉伸试验机等测试方法，研究了中间层扩散钎焊工艺参数与接头界面结构及力学性能之间的关系，并且分析了钎焊接头的形成过程。 首次以Al箔、Zn箔作为中间层，利用扩散钎焊方法实现了AZ31B/Cu异种金属的冶金结合，降低了AZ31B/Cu直接进行扩散钎焊的温度，分别降低了100℃、150℃。 以Al箔为中间层对AZ31B/Cu扩散钎焊接头，界面扩散区的宽度随着保温时间的延长而增加。在焊接温度450℃、保温时间120min、压力为2.5MPa的条件下，接头扩散区的宽度最高达到500 m。在接头AZ31B侧依次形成 -Mg、（ -Mg+ Mg12Al17）共晶组织、Mg12Al17金属间化合物，在Cu侧依次形成 -Cu固溶体，AlCu4金属间化合物。接头界面扩散区的硬度呈梯度分布，最高硬度达到了185HV。焊接接头的剪切强度随保温时间的延长呈现出先升高后降低的规律，当焊接温度为450℃、压力为2.5MPa、保温时间为90min的条件下，接头的剪切强度达到最大值65MPa，约为AZ31B镁合金母材的40%。焊接接头断口出现在中间扩散层区域，并且断口呈现出沿晶界断裂的解理混合型断口。 以Zn箔为中间层的AZ31B/Cu扩散钎焊接头，随着焊接温度和保温时间的的升高，扩散区的宽度越宽，共晶组织越细小。在焊接温度410℃、压力为2.5MPa、保温时间50min的条件下，接头扩散区的宽度达到最大值200 m。接头显微组织从AZ31B侧向Cu侧依次为先共晶相 -Mg、（ -Mg+MgZn+Mg2Zn11）共晶相、Mg-Zn金属间化合物、Cu5Zn8金属间化合物、 -Cu固溶体。接头界面扩散区的硬度呈现中间高、靠近母材两侧逐渐降低的分布规律，当焊接温度为410℃，保温时间为40min的条件下，接头的显微硬度达到最大为350HV。焊接接头的剪切强度随温度的升高和保温时间的延长，呈现出先升高后降低的分布规律，当焊接温度为410℃、保温时间为40min、压力为2.5MPa条件下，接头的剪切强度达到了最大值45MPa，约为AZ31B镁合金的26%。焊接接头断口出现在Cu基体一侧，并呈现脆性-韧性混合型断口。 扩散钎焊接头形成过程大致分为三个阶段，一固相扩散阶段，二产生共晶液相并铺展阶段，三凝固形成接头阶段。

Magnesium and magnesium alloys have the proportion of small, specific strength and specific stiffness, conductivity and thermal conductivity, good damping properties of a series of advantages, copper and copper alloy not only have excellent thermal conductivity, good ductility and corrosion sex, hot and cold processing performance, but also have a high resistance to oxidation and corrosion resistance, high strength. Magnesium and copper which make them excellent performance have been widely used in engineering, such as aerospace, defense and automotive, computer and other fields. In this paper, with Al foil ang Zn foil as interlayer, by means of SEM、EDS、XRD、testermicrohardness testing methods、electronic universal tensile，microstructure and properties of interfacial microstructure of the joint were researched, and the optimum technological parameters were identified with Al foil, Zn foil as interlayer for diffusion brazing of AZ31B/Cu. For the first time use the Al foil and Zn foil as intermediate layer, realizes the AZ31B/Cu dissimilar metal metallurgical bonding by diffusion brazing method, which reduces the AZ31B/Cu direct diffusion brazing temperature. The temperature were decreased by 100 ℃, 150 ℃. The diffusion brazing of AZ31B/Cu used Al foil as interlayer, the diffusion zone width of joint widen as the holding time increases. When soldering temperature reaches 420 ℃, holding time is 120min, the pressure is 2.5MPa, the diffusion width of the joint reached about 400 m. The phase structure on the AZ31B side are -Mg 、( -Mg+ Mg12Al17) eutectic zone、Mg12Al17 intermetallic compound, and the phase structure on the copper side are Al-Cu solid solution、Al-Cu intermetallic compound. The microhardness of the welded joint showing a gradient distribution. The maximum hardness reaches 185HV. The shear strength of welded joints shows the law of first increases and then decreases with holding time increasing. When soldering temperature is 450 ℃, pressure is 2.5MPa, the holding time is 90min,the maximum shear strength of the joint reaches 65MPa,which reaches approximately 40% AZ31B magnesium alloy. Welded joint fracture occurs in the middle region of the diffusion layer. Fracture of the joint showing mixed fracture of cleavage fracture along grain boundaries. The diffusion brazing of AZ31B/Cu used Zn foil as interlayer, when the temperature reaches 410℃，holding time is 50min, a pressure is 2.5MPa，the diffusion width of the joint reached about 200 m, and the composition of the diffusion layer is not uniform. Microstructure phase structure are mainly -Mg, rose-like （ -Mg+MgZn+Mg2Zn11）eutectic phase and Mg2Zn11 intermetallic compound, the metal compound of Cu5Zn8,Cu solid solution. Microhardness of diffusion zone presents the law that is high in the middle, the lower close to the base material. When the temperature is 410 ℃, holding time is 40min,the maximum hardness of the joint reaches 350HV. Shear strength of welded joints with temperature and holding time increasing, which shows the law of first increases and then decreased. When the temperature is 410 ℃, holding time is 40min, pressure is 2.5MPa, the maximum shear strength of the joint reaches 45MPa,which reaches approximately 26% AZ31B magnesium alloy. Welded joints fracture is in Cu substrate side, and showed brittle - ductile mixed fracture. The formation process of diffusion brazed joint is broadly divided into three phases, the first is solid phase diffusion stage, the second is generating and spreading of the eutectic liquid phase, the third that is phase solidify to form the joint.