(1. 南昌大学 机电工程学院，南昌 330031；
2. 桂林理工大学 材料科学与工程学院，桂林 541004)
摘 要: 本文以AZ31B Mg/6061-T6Al为研究对象，对界面添加锌、铜和银箔并采用超声波点焊进行焊接来考察接头性能。采用金相显微镜、SEM、XRD和拉伸试验机等研究了接头的显微组织和力学性能。结果表明： Mg/Al接头在焊接时间为1.1 s时接头温度达358.6 ℃，界面形成由Al12Mg17和Al3Mg2组成的连续IMC脆性层，降低了接头力学性能，断口为脆性解离断裂；添加锌箔能降低获得可靠接头的焊接时间，0.5 s时接头最大拉剪力为1154.4 N、撕裂力为146.9 N，断口表现出韧性断裂特征，随焊接时间延长锌箔的有效性降低；添加铜箔可有效阻隔Mg-Al系IMC的形成，但由于Mg/Cu焊接性差，导致接头力学性能较低；添加银箔亦能有效阻隔Mg-Al系IMC的形成，1.1 s时接头拉剪力达到最大值为1141.4 N，但撕裂力较小(72.2 N)，Mg/Ag界面断口呈现脆性断裂特征。
关键字: 超声波点焊；Mg/Al异质合金；金属间化合物(IMC)；金属箔片；力学性能
（1. School of Mechanical & Electrical Engineering, Nanchang University, Nanchang 330031, China;
2. School of materials science and Engineering, Guilin University of Technology, Guilin 541004, China）
Abstract:In this paper, AZ31B Mg/6061-T6 Al was used as the research object. The foils of Zn, Cu and Ag were added to the interface, respectively, and ultrasonic spot welding was used to inspect the joint performance. The microstructure and mechanical properties of the joints were investigated by metallographic microscope, SEM, XRD and tensile tester. The results show that when the welding time is 1.1 s, the joint temperature reaches 358.6 °C, and the interface forms a continuous IMC brittle layer composed of Al12Mg17 and Al3Mg2, which reduces the mechanical properties of the joint and the fracture is brittle dissociative fracture. Adding Zn foil to the interface can reduce the welding time for obtaining reliable joints. The maximum tensile shear force is 1154.4 N and the tear force is 146.9 N at 0.5 s. The fracture shows the characteristics of toughness, and the effectiveness of Zn foil decreases with the increase of welding time. The addition of Cu foil effectively blocks the formation of Mg-Al IMC, however, due to the poor weldability of Mg/Cu, the mechanical properties of the joint are very poor. The addition of Ag foil can also effectively block the formation of Mg-Al IMC. The tensile shear force of the joint reaches a maximum of 1141.4 N at 1.1 s, but the tearing force is small (72.2 N). The fracture of the Mg/Ag interface exhibits brittle fracture characteristics.
Key words: ultrasonic spot welding; Mg/Al heteroalloy; intermetallic compounds; metal foil; mechanical property
