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Zhang M.,Nanjing University of Aeronautics and Astronautics | Zhang M.,Huaiyin Institute of Technology | Xue S.,Nanjing University of Aeronautics and Astronautics | Ji F.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2011

Cu/Al dissimilar metals were brazed with Zn-Al filler metals by torch-brazing technology, and the effects of Al on the spreadability and microstructure of Zn-Al filler metal were investigated separately. Moreover, the strength and microstructure of the brazed joint were also studied. Results indicate that the strength of the brazed joints achieves the optimum status when the Al content of filler metals is 15%. SEM and EDS are used to study the microstructure and phase constitution of the filler metals and brazed joints respectively. Experimental results show the microstructures of brazed joints are mainly consisted of Zn-based solid solution when Al content is low. However, CuAl2 intermetallic compounds can form in the brazing seam region with increase of Al content. When Al content is 22 wt.%, CuAl2 intermetallic compounds become coarse, and the strength of brazed joint decreases. Source


Dai W.,Nanjing University of Aeronautics and Astronautics | Xue S.,Nanjing University of Aeronautics and Astronautics | Lou J.,Zhejiang Xinrui Welding Material Co. | Wang S.,Zhejiang Xinrui Welding Material Co.
Materials and Design | Year: 2012

To develop new aluminum filler metals used for brazing 6061 alloy, the microstructure and properties of Al-6.5Si-42Zn-xSr alloys with different Sr content were studied. The results showed that the melting point of Al-6.5Si-42Zn alloy is around 520 °C, and Sr addition did not change the melting point of the filler metals, yet trace amounts of them greatly improved the microstructure of the alloys. As Sr content increased, the number of primary Si particles decreased and the eutectic Si changed from acicular to fine fibrous morphology in the Al-6.5Si-42Zn-xSr alloys. Meanwhile, Sr also refined the β-Fe intermetallic compound in the alloy. The wettability of the Al-6.5Si-42Zn-xSr brazing alloys improved with increasing Sr content, in addition, it was found that Sr addition also modified the microstructure of the brazing joints. From the tensile test results, the strength of the lap joints and the butt joints could be increased by 14% and 11%. © 2012 Elsevier Ltd. Source


Dai W.,Nanjing University of Aeronautics and Astronautics | Xue S.,Nanjing University of Aeronautics and Astronautics | Lou J.,Zhejiang Xinrui Welding Material Co. | Wang S.,Zhejiang Xinrui Welding Material Co.
Materials Transactions | Year: 2012

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. Source


Ji F.,Nanjing University of Aeronautics and Astronautics | Xue S.,Nanjing University of Aeronautics and Astronautics | Liu S.,Nanjing University of Aeronautics and Astronautics | Lou J.,Zhejiang Xinrui Welding Material Co. | Lou Y.,Zhejiang Xinrui Welding Material Co.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2013

The creep behavior of Zn-22Al and Zn-22Al-0.03Ti filler metals at room temperature were studied by nanoindentation in this paper, and constant loading rate method was used to calculate the creep stress exponent. The results indicate that, both the Zn-22Al and Zn-22Al-0.03Ti produced obvious creep deformation under holding load. Both the depth and creep displacement of Zn-22Al-0.03Ti were less than that of Zn-22Al, and the maximum difference were 15.68% and 26.87%, respectively. Under the constant time, the filler metals produced different creep displacement with different loadings. The creep stress exponents of two filler metals at room temperature were obtained by fitting method. Zn-22Al-0.03Ti had a higher creep stress exponent than Zn-22Al filler metal, which implied that Ti-bearing filler metals had better creep resistance than Zn-22Al alloy. The grain of Zn-22Al filler metal could be refined remarkably with the Ti addition, which might result in the increase of grain boundary and finally enhanced the creep resistance of alloy. Source


Zhang S.,Nanjing University of Aeronautics and Astronautics | Xue S.,Nanjing University of Aeronautics and Astronautics | Yang J.,Nanjing University of Aeronautics and Astronautics | Lou J.,Zhejiang Xinrui Welding Material Co. | Wang S.,Zhejiang Xinrui Welding Material Co.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2013

The effect of P on the spreadability, micro-structure of Al-Si-Zn filler metal and the mechanical properties of brazed joints were studied. Results show that the spreadability of the Al-Si-Zn filler metal was improved by the addition of P, and furthermore, both the plate shape primary silicon and needle shape eutectic silicon of the filler metal were refined effectively. Tensile tests indicate that the fracture position of lap joints locates at the base metal and butt joints locates at brazing seam respectively, and the tensile strength of the butt joint brazed with Al-Si-Zn filler metal increased firstly, and then decreased with the increasing of P addition. When the content of P was about 0.06%, the comprehensive properties of the Al-Si-Zn filler metal were the best. Source

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