Abstract:

The liquidus and incipient melting temperatures of DD3 superalloy are about 23℃ and 60℃ higher than those of K3 alloy respectively. As Ti content decreases to 1.5%, the eutectic（γ+ γ'）in the alloy can be eliminated. This raises the liquidus and solidus temperatures 10℃ and 60℃ further.The effect of carbon on solidus and liquidus is far less than those of Zr and B. In some degree the influence of C is inferior to Ti. The DD3 superalloy with low C content and without eutectic（γ + γ'）has higher resistance to hot cracking.

Key words: nickel-base superalloys, isothermal solidification, pre- cipitation of primary phases, effbct of carbon and titanium