(1. 南昌大學(xué) 機(jī)電工程學(xué)院，南昌 330031；
2. 桂林理工大學(xué) 材料科學(xué)與工程學(xué)院，桂林 541004)
摘 要: 本文以AZ31B Mg/6061-T6Al為研究對象，對界面添加鋅、銅和銀箔并采用超聲波點(diǎn)焊進(jìn)行焊接來考察接頭性能。采用金相顯微鏡、SEM、XRD和拉伸試驗(yàn)機(jī)等研究了接頭的顯微組織和力學(xué)性能。結(jié)果表明： Mg/Al接頭在焊接時(shí)間為1.1 s時(shí)接頭溫度達(dá)358.6 ℃，界面形成由Al12Mg17和Al3Mg2組成的連續(xù)IMC脆性層，降低了接頭力學(xué)性能，斷口為脆性解離斷裂；添加鋅箔能降低獲得可靠接頭的焊接時(shí)間，0.5 s時(shí)接頭最大拉剪力為1154.4 N、撕裂力為146.9 N，斷口表現(xiàn)出韌性斷裂特征，隨焊接時(shí)間延長鋅箔的有效性降低；添加銅箔可有效阻隔Mg-Al系IMC的形成，但由于Mg/Cu焊接性差，導(dǎo)致接頭力學(xué)性能較低；添加銀箔亦能有效阻隔Mg-Al系IMC的形成，1.1 s時(shí)接頭拉剪力達(dá)到最大值為1141.4 N，但撕裂力較小(72.2 N)，Mg/Ag界面斷口呈現(xiàn)脆性斷裂特征。
關(guān)鍵字: 超聲波點(diǎn)焊；Mg/Al異質(zhì)合金；金屬間化合物(IMC)；金屬箔片；力學(xué)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
