Mg-Al-Zn三元金属间化合物对采用Al/Zn/Cu/Zn复合中间层的MB8/2024超声辅助钎焊接头的增强作用

Reinforcement effect of Mg−Al−Zn ternary IMC on MB8/2024 joints with Al/Zn/Cu/Zn multi-interlayer via ultrasonic-assisted brazing

研究采用Al/Zn/Cu/Zn复合中间层的MB8/2024超声辅助钎焊接头的显微组织演变规律。结果表明,在MB8母材与铜箔之间添加铝箔可实现这两者界面上的金属间化合物由Al_(3)Mg_(2)向AlMg_(4)Zn_(11)的转变。这个转变增强接头的力学性能,并且在超声作用22 s时获得最高剪切强度为85.26 MPa的接头。热力学分析表明,Al_(3)Mg_(2)和AlMg_(4)Zn_(11)的吉布斯自由能分别为-31.94 kJ/mol和-38.65 kJ/mol,这为该转变提供热力学基础。由于空化效应的影响,首次在超声辅助钎焊中发现Mg32(Al,Zn)_(49)准晶。

The evolution of microstructure in the MB8/2024 dissimilar alloy joints by using Al/Zn/Cu/Zn multi-interlayers via ultrasonic-assisted brazing was investigated.The results show that the addition of aluminum foil on the MB8 side realized the transformation of Al_(3)Mg_(2)binary intermetallic compounds(IMCs)to AlMg_(4)Zn_(11) ternary IMCs along the interface between copper foil and MB8 magnesium alloys.This transformation reinforced the joints and then the shear strength reached a maximum at 22 s(85.26 MPa).Thermodynamic analysis shows that∆GMg,Al,Zn of AlMg_(4)Zn_(11)(−38.65 kJ/mol)was smaller than that of Al_(3)Mg_(2)(−31.94 kJ/mol),which provided a basis for the IMC transformation.Mg32(Al,Zn)_(49)quasicrystal was found for the first time using ultrasonic-assisted brazing due to the cavitation effect.