On the Effect of Super-Solidus Heat Treatment on the Microstructure and Creep Properties of a Third-Generation Single Crystal Ni-Based Superalloy

A Super-Solidus Hot Isostatic PressingHot isostatic pressing, SSHIPSuper-Solidus Hot Isostatic Pressing (SSHIP), heat treatmentHeat treatment has been developed and applied to the third-generation Ni-based single crystal superalloyNi-based single crystal superalloy CMSX-4 PlusCMSX-4 plus. The aim of this new type of heat treatmentHeat treatment is to significantly reduce the solution heat treatmentSolution heat treatment time and improve the mechanical propertiesMechanical properties compared to those resulting from subjecting the single crystalSingle crystal to conventional heat treatmentHeat treatment routes. The partial melting of the regions with the lowest solidus temperatures during SSHIPSuper-Solidus Hot Isostatic Pressing (SSHIP) results in the acceleration of the diffusional processes, while the control of the cooling rate after SSHIPSuper-Solidus Hot Isostatic Pressing (SSHIP) results in the optimum precipitationPrecipitation of the fine γ/γ′ microstructureMicrostructure. This innovative type of heat treatmentHeat treatment, which can significantly reduce the economic penalties associated with lengthy high-temperatureHigh-temperature solution treatments while having a positive effect on the final mechanical propertiesMechanical properties, could be applied to other complex single crystalSingle crystal Ni-based superalloysNi- based superalloy containing large amounts of refractory elements (like rhenium, tungsten and tantalumTantalum), showing strong dendritic segregationSegregation and/or a large volume fraction of eutectics in the as-cast state.