Effect of rare earth elements on brazing process performance of Al-Si-Zn-Cu filler metal

In order to investigate the influence of Ce-La mischmetal on Al-Si-Zn-Cu brazing filler metal, the microstructure, mechanical properties and wettability of brazing filler metal with varying dosage of mischmetal addition were studied. Result shows that in Al-Si-3Zn-15Cu alloy, both tensile strength and wettability increase with the content of rare earth elements. The fundamental phase of Al-Si-3Zn-15Cu areα-Al/Al-Si/Al-Si-Cu/Si, the addition of La and Ce reduces the grain boundary segregation of impurity elements, decreases the crystallization rate and refines the grainsize. Besides, the strength and ductility are improved because of the modification effect of rare earth elements on the net structure of second phase particles.