Microstructure and mechanical properties of Cu/Al joints brazed using (Cu, Ni, Zr, Er)-modified Al-Si filler alloys
(1. Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310023, China;
2. Engineering Research Center of Process Equipment and Remanufacturing, Ministry of Education, Zhejiang University of Technology, Hangzhou 310023, China;
3. College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China;
4. Innovation Research Institute of Zhejiang University of Technology (Shengzhou), Shengzhou 312400, China;
5. Taizhou Special Equipment Inspection and Testing Research Institute, Taizhou 318000, China)
2. Engineering Research Center of Process Equipment and Remanufacturing, Ministry of Education, Zhejiang University of Technology, Hangzhou 310023, China;
3. College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China;
4. Innovation Research Institute of Zhejiang University of Technology (Shengzhou), Shengzhou 312400, China;
5. Taizhou Special Equipment Inspection and Testing Research Institute, Taizhou 318000, China)
Abstract: To design a promising Al-Si filler alloy with a relatively low melting-point, good strength and plasticity for the Cu/Al joint, the Cu, Ni, Zr and Er elements were innovatively added to modify the traditional Al-Si eutectic filler. The microstructure and mechanical properties of filler alloys and Cu/Al joints were investigated. The result indicated that the Al-Si-Ni-Cu filler alloys mainly consisted of Al(s,s), Al2(Cu,Ni) and Si(s,s). The Al-10Si-2Ni-6Cu filler alloy exhibited relatively low solidus (521 °C) and liquidus (577 °C) temperature, good tensile strength (305.8 MPa) and fracture elongation (8.5%). The corresponding Cu/Al joint brazed using Al-10Si-2Ni-6Cu filler was mainly composed of Al8(Mn,Fe)2Si, Al2(Cu,Ni)3, Al(Cu,Ni), Al2(Cu,Ni) and Al(s,s), yielding a shear strength of (90.3±10.7) MPa. The joint strength was further improved to (94.6±2.5) MPa when the joint was brazed using the Al-10Si-2Ni-6Cu-0.2Er-0.2Zr filler alloy. Consequently, the (Cu, Ni, Zr, Er)-modified Al-Si filler alloy was suitable for obtaining high-quality Cu/Al brazed joints.
Key words: Cu/Al joint; brazing; Al-Si filler alloy; interface structure; joint strength