Abstract
A new type of low melting point Al-Si-Cu (Ni) filler metal for brazed 6063 aluminum alloy was designed, and the microstructure and properties of the filler metal were systematically studied. The results show that when the content of Cu in the Al-Si-Cu filler metal increased from 10 wt.% to 20 wt.%, the liquidus temperature of the filler metal decreased from 587.8 °C to 533.4 °C. Its microstructures were mainly composed of the α-Al phase, a primary Si phase, and a θ(Al2Cu) phase. After a proper amount of Ni was added to the Al-Si-20Cu filler metal, its melting range was narrowed, the spreading wettability was improved, and the microstructure was refined. Its microstructure mainly includes α-Al solid solution, Si particles, and θ(Al2Cu) and δ(Al3Ni2) intermetallic compounds. The results of the shear strength test indicate that the shear strength of the brazed joint with Al-6.5Si-20Cu-2.0Ni filler metal was 150.4 MPa, which was 28.32% higher than that of the brazed joint with Al-6.5Si-20Cu filler metal.
Highlights
Accepted: 7 May 2021Brazing holds the advantages of low deformation of the weldment, high dimensional accuracy, and high production efficiency
As a light alloy material with excellent weldability and heat conductivity, 6063 aluminum alloy can be used as the main material of the heat exchanger [4,5,6]
To obtain excellent brazed joints, the brazing temperature must be higher than 595 ◦ C, which is close to the solid phase temperature of 6063 aluminum alloy, which may cause base metal grain growth or over-burning [2,4,7]
Summary
Accepted: 7 May 2021Brazing holds the advantages of low deformation of the weldment, high dimensional accuracy, and high production efficiency. As a light alloy material with excellent weldability and heat conductivity, 6063 aluminum alloy can be used as the main material of the heat exchanger [4,5,6]. To obtain excellent brazed joints, the brazing temperature must be higher than 595 ◦ C, which is close to the solid phase temperature of 6063 aluminum alloy (approximately 615 ◦ C), which may cause base metal grain growth or over-burning [2,4,7]. An excessive brazing temperature enhances the manufacturing cost and causes dissolution of the base metal, and the quality of the brazed joint obtained is poor [5,9]. It is becoming increasingly important to develop a new type of low melting point, aluminum-based filler metal for low-cost and high-quality aluminum alloy brazed joints
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