Brazing of 6061 aluminum alloy/Ti-6Al-4V using Al-Si-Cu-Ge filler metals

Al-8.4Si-20Cu-10Ge and mixed rare-earth elements (Re) containing Al-8.4Si-20Cu-10Ge-0.1Re filler metals were used for brazing of 6061 aluminum alloy/Ti-6Al-4V. The addition of 20 wt.% copper and 10 wt.% germanium into the Al-12Si filler metal lowered the solidus temperature from 586 degrees C to 489 degrees C and the liquidus temperature from 592 degrees C to 513 degrees C. The addition of 0.1 wt.% rare-earth elements into Al-8.4Si-20Cu-10Ge alloy caused remarkable Al-rich phase refinement and transformed the needle-like Al2Cu intermetallic compounds into block-like shapes. Shear strengths of the 6061 aluminum alloy/Ti-6AI-4V joints with the two brazing filler metals. Al-8.4Si-20Cu-10Ge and Al-8.4S-20Cu-10Ge-0.1Re, varied insignificantly with brazing periods of 10-60 min. The average shear strength of the 6061 aluminum alloy/Ti-6Al-4V joints brazed with Al-8.4Si-20Cu-10Ge at 530 degrees C was about 20 MPa. Rare-earth elements appeared to improve the reaction of the Al-8.45i-20Cu-10Ge filler metal with Ti-6Al-4V. The joint shear strength of the 6061 aluminum alloy/TI-6Al-4V with Al-8.4Si-20Cu-10Ge-0.1 Re reached about 51 MPa. (C) 2011 Elsevier B.V. All rights reserved.