Abstract: The peak at 1135-1160℃ on the DTA curve during heating corresponds to the melting range of Ni5Hf phase as its volume fraction is greater than 1 %.The formation of the Ni5Hf phase induced the incipient melting of Hf-bearing cast nickel-base superalloy. A distinct segregation of Ni5Hf phase between the top and the bottom of the directionally solidified ingots was noticed, and consequently their sensitivities to incipient melting are quite different. It was found that more Ni5Hf phases were formed in the low-carbon or carbon-free zone of the alloy DZ22 and promoted incipient melting of the alloy.By means of a pretreatment at 1150℃ for 8h, Ni5Hf phase can be eliminated and therefore the final solution treatment temperature can be raised nearly 50℃ which brings about a homogenezing effect and further increase in the stress-rupture properties of the alloy at 1040℃.