Microstructure and properties of 6061 aluminum alloy brazing joint with alsizn filler metal

Abstract

Ternary AlSiZn filler metals were designed in order to join the 6061 aluminum alloy. The microstructure, phase constitution and fracture morphology of the brazed joint were investigated. Results of the microstructure observation showed that eutectoid α(Al) + η(Zn), α(Al) solid solution, as well as Si particles formed in the filler metal. The melting points of these filler metals are much lower than Al12Si alloy. The ×(Zn), α(Al) solid solution, and the primary Si particles were found in the 6061 Al brazing seam when using Al0.2Si78Zn and Al2Si62Zn filler metal, while the AlSi eutectic were found when using Al6.5Si42Zn alloy. Results also indicate that the tensile strength of the 6061 Al brazed joints using Al0.2Si78Zn, Al2Si62Zn and Al6.5Si42Zn is 101, 109, 129 MPa, respectively. The fracture morphology of the brazed joints showed intergranular fracture mode while some transgranular fracture could be found in the joint of Al6.5Si42Zn filler metal. © 2012 The Japan Institute of Metals.