Al2O3陶瓷/AlSiMg/1A95铝合金间接钎焊接头组织与性能的研究

采用Al-Si-Mg钎料制备了表面Mo-Mn化后镀Ni的Al2O3陶瓷与1A95铝合金真空钎焊接头,研究了钎焊温度和保温时间对钎焊接头组织和剪切性能的影响,并分析了接头的界面微观组织及断口形貌。研究表明,最佳钎焊工艺为580℃×20 min,接头的抗剪强度达到74 MPa,此时接头界面结构为Al2O3/Mo-Mn/Al3Ni/α-Al/1A95。随着钎焊温度的升高,界面处Al3Ni化合物厚度增加;随着保温时间的延长,界面处产生了Al12Mo化合物覆盖在Al3Ni化合物上方。接头的断裂形式均为脆性断裂:当钎焊温度较低保温时间较短时,断裂主要发生在靠近铝合金与钎料层的界面处。最佳工艺条件下,断裂一部分发生在钎料和镀镍层的反应区内,一部分发生在靠近铝合金与钎料层的界面处。随着钎焊温度或保温时间进一步提高,断裂主要发生在钎料和镀镍层的反应区内。

Study on microstructure and properties of indirectly brazed joint of Al2O3 ceramic/AlSiMg/1A95 aluminum alloy

The joint of 1 A95 aluminum alloy with Al2O3 ceramic that was coated with Ni after Mo-Mn superficial treatment was vacuum brazed with Al-Si-Mg solder alloy. The influences of brazing temperature and holding time on the microstructures and shear properties of brazed joint were studied,and the microstructures and fracture morphology of the joint were analyzed. The results show that the shear strength of the joint reaches to maximum value of 74 MPa at the brazing temperature 580 ℃ and holding time of 20 min. Under the optimized condition,the microstructures of the joint are Al2O3/Mo-Mn/Al3 Ni/α-Al/1 A95. With the brazing temperature increasing,the thickness of Al3 Ni compound at the interface increases. Moreover,with the holding time prolonging,the Al12 Mo compound forms at the interface and covers above the pre-formed Al3 Ni compound. The fracture mode of the joints is brittle fracture for all the cases. When the brazing temperature is relatively low and the holding time is relatively short,the fracture occurs mainly near the interface between the aluminum alloy and the brazing alloy. Under the optimum process,the fracture occurs both in the reaction zone of the brazing alloy/nickel plated layer,and near the interfacial zone between the aluminum alloy and brazing alloy. If the brazing temperature or holding time is further elevated,the fracture occurs mainly in the reaction zone of the brazing alloy and nickel plated layer.