Effects of Sb and rare earth on properties of Zn-10Al based brazing filler metals and brazed joints

Adding elements of Sb and rare earth to Zn-10Al-5Cu based brazing filler metals, using vacuum furnace, universal material testing machine, metallographic and scanning electron microscope equipment, the influence of Sb and rare earth additions on the microstructure, properties of Zn-10Al-5Cu based brazing filler metals and properties of brazed joints were studied. The results show that the spreading area of brazing filler increases rapidly with the addition of Sb element, and then tends to be stable. The tensile strength increase with the addition of Sb increased steadily increased. The structure of brazing filler is formed by mixing eutectoid and eutectic structure. Adding rare earth LaNd in selected Zn10Al5Cu1.5Sb brazing filler, the wettability of filler metal has been further improved, when the dosage is 0.15%, the wettability of brazing filler at best, In this case, the dendrite structure of grey and coarse tree and the black layer block tissue are reduced, gray and black lamellar microstructure increase and become small, the based tissue is maximally refined, the strength of the filler metal and brazed joints reaches the maximum. continue to increase of the amount of rare earth, the wettability of brazing filler and the shear strength of brazed joints decreased instead.