Effect of mixed rare earth and Sr on microstructure and brazability of Al-20Cu-5Si-2Ni filler metal

The objective of this study is to investigate the influence of adding tiny amount of mixed rare earth（La,Ce） and Sr to Al-20Cu-5 Si-2Ni filler metal,by analyzing the microstructure,wettability and mechanical properties of brazed joints.The results show tha with the addition of mixed rare earth（La,Ce） into Al-20Cu-5Si-2Ni alloy,the α-Al solid solution as well as CuAl₂（Ni） intermetallic compound phase significantly reduced,while more Al-Si eutectic phase and Al-Si-Cu ternary eutectic phase were produced.And as mixed rare earth（La,Ce） added in,the wettability of Al-20Cu-5Si-2Ni filler metal decreased,while the shear strength of the brazed joints increased.The addition of Minor Sr modificated Al-20Cu-5Si-2Ni filler metal,further reduced the CuAl₂（Ni） intermetallic compound phase,which was partially replaced Al-Si-Cu ternary eutectic phase.As a result,the tensile strength as well as the wettability of the filler metal was improved.