In order to meet the requirements of marine gas turbine blade materials, a, new-type directional solidification Ni-based superalloy named DZ68 was developed. The alloy composition was designed by low segregation technology. Its nominal chemical composition (mass fraction, %) is C 0.05, Cr 12.0, Mo 1.0, W 5.0, Co 8.5, Al 5.3, Ti 0.5, Ta 5.0, Re 2.0, B 0.01, and balance is Ni. The microstructures of as-east DZ68 alloy and after heat treatment states were analyzed by OM, SEM and XRD. The tensile, rupture and hot corrosion resistance properties of DZ68 alloy were compared with DZ125 and IN738 alloys. Results show that the microstructure of as-cast DZ68 alloy is composed of gamma, gamma', (gamma+gamma') eutectics, MC type carbides and a few borides. After heat treatment, the microstructure of DZ68 alloy is composed of gamma, gamma' and carbides. The carbides are mainly MC and M23C6. The tensile strength of DZ68 alloy decreases slightly with the increase of temperature, and reaches its minimum value at 700 degrees C. When the temperature is higher than 700 degrees C, the tensile strength increases so evidently that reaches its maximum at once at 760 degrees C, But when the temperature is higher than 760 degrees C its tensile strength decreases obviously. It is well recognized the relationship of the tensile strength of DZ68 alloy with temperature is abnormal, similar to that of its yield strength but opposite to that of its plasticity. The tensile and rupture properties of DZ68 alloy are nearly the same as those of DZ125 alloy and its hot corrosion resistance property is nearly the same as that of IN738 alloy under the same conditions.
