| Summary: | 碩士 === 雲林科技大學 === 機械工程系碩士班 === 96 === In the research, low-melting-point aluminum brazing filler metals based on Al-12Si were developed and used to join 6061 aluminum alloy. Moreover, the effects of the addition of copper, germanium, zinc and rare earth elements in Al-Si alloys upon the joining of aluminum alloys were investigated. By way of differential thermal analysis (DTA), the melting temperatures of Al-Si-Cu, Al-Si-Cu-Ge and Al-Si-Cu-Zn filler metals were determined. The results showed that the addition of 10-20 wt.% Cu into the Al-Si eutectic alloy causes decreasing its liquidus from 570℃ to 535℃. An addition of 10 wt.% Ge into the Al-Si-Cu ternary alloys causes their liquidus temperatures decrease about 22℃. An addition of 10 wt.% Zn and 0.1 wt.% Mm into the Al-Si-Cu ternary alloys have an average solidus temperature at about 502℃. Metallographic observations indicated that the addition of Cu and Ge into the Al-Si-Cu alloys would form Al2Cu intermetallic phase, Al-Si eutectic phase, silicon particles, Al-rich phase, and Si-Ge phase. An addition of 0.1 wt.% Mm into the Al-Si-Cu-Zn filler metals formed an Al-La intermetallic compound. Vacuum brazing results showed that using the Al-10.8Si-10Cu metal filler to join 6061 aluminum alloy the shear strengths increased with the increase of joining period. However, the shear strengths of 6061 aluminum alloy joints which the addition of Ge into the Al-Si-Cu ternary alloys were used showed obviously lower shear strengths. Using Al-Si-Cu-Zn filler metals to join 6061 aluminum alloys, the shear strengths were obviously higher than using of Al-Si-Cu and Al-Si-Cu-Ge alloys. The shear strengths of 6061 aluminum alloy joints using Al-8.4Si-20Cu-10Zn-0.1Mm metals fillers decreased with the increase of joining period. The average shear strength was 77 MPa for ten minutes joining.
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