Brazing of 6061 aluminum alloy with the novel Al-Si-Ge-Zn filler metal

• 6061 aluminum alloy is brazed with Al-Si-Ge-Zn filler metal for the first time.
• High-quality brazed joints can be achieved using the novel Al-Si-Ge-Zn filler metal
• Optimized shear strength of 138.2 MPa can be achieved.
• Brazed joint presents obvious ductile fracture characteristics.

The novel Al-Si-Ge-Zn filler metal was used for brazing 6061 aluminum alloy. Microstructure and properties of the filler metal and brazed joint were studied. The results showed that the main phases in the Al-Si-Ge-Zn filler metal as well as the brazed seam were α-Al, β-GeSi, and η-Zn phases. Compared with the common Al-Si-Ge and Al-Si-Zn filler metals, it had smaller and better dispersive β-GeSi solid solution phases without coarse primary Si phase. The melting temperature of Al-Si-Ge-Zn filler metal is 505.2~545.1 °C, and the narrow melting temperature interval is favorable for the brazing process. When this filler metal was used to braze the 6061 aluminum alloy, an optimized shear strength of 138.2 MPa was achieved. Observation of the fracture section showed that the brazed joints presented obvious ductile fracture characteristics.