A new low thermal expansion nickel-based superalloy has been developed for high-temperature applications ranging from 760 °C to 816 °C. Traditional Invar-type alloys suffer from limited service temperatures due to magnetic phase transitions and poor oxidation resistance. To overcome these limitations, the present study builds upon the Ni–Cr–Mo–W system, incorporating γ′ and γ ″-forming elements such as Al, Ti, and V to enhance mechanical strength and thermal stability. Three experimental alloys were produced and evaluated through microstructural characterization, differential scanning calorimetry, tensile testing, and thermal expansion measurements. Results show that the addition of Al promotes the formation of P and µ phases, refining grain structure and improving ductility at elevated temperatures. Despite reduced Ni 2 M content in Al-bearing alloys, high strength and high ductility were observed. All experimental alloys exhibited lower coefficients of thermal expansion than Waspaloy while maintaining equivalent or superior high-temperature mechanical performance. These findings suggest that tailored precipitation of P, µ , γ′ , and Ni 2 M phases can enable the design of superalloys with enhanced strength, ductility, and thermal stability for extended service at elevated temperatures.
Zhou et al. (Tue,) studied this question.