Brazing of IC10 superalloy with Ni-based brazing fillers using Hf and Zr as melting-point depressants

Three Ni-based brazing fillers were designed using Hf, Zr and Hf+Zr as melting-point depressant respectively with the addition of a certain amount of Cr, Co, and Mo.The liquidus-temperature, hardness and spreadability of three fillers were measured.The results signify that Hf can decrease the hardness and improve the spreadability of filler more effectively than Zr.But as to the capability of depressing the liquidus-temperature, Zr is superior to Hf.The tensile strengths at 900℃ of the joints bonded with three fillers were also tested.It shows that the strength of joint brazed with the filler using Hf+Zr as melting-point depressant is higher than the others.In particular, Zr-containing filler presents the lowest joint strength.Furthermore, the high-temperature strength of the joint can be improved by adding a certain amount of Zr to Ni-Hf filler.