Determination of Grain-Scale Effective Properties in a CM 247 LC Nickel-Based Superalloy Using Spherical Indentation and Bayesian Inference

Nickel-based superalloys achieve their remarkable high-temperature performance through a complex γ – γ ′ microstructure, but direct measurements of grain-scale elastic constants and critical resolved shear stress (CRSS) remain scarce. In this study, we measured the material response at the scale of individual grains in a polycrystalline Ni-based superalloy containing a γ – γ ′ microstructure, thereby obtaining the effective grain-scale behavior from which elastic constants and CRSS were estimated. The methodology integrates spherical indentation stress–strain protocols, crystal plasticity finite element simulations, symmetry-aware representation of the grain orientations in the face-centered cubic material sample via surface spherical harmonics (SSH), Gaussian process surrogate modeling, and Bayesian inference, with a refined analysis of the elastic regime ensuring that the indentation zone encompassed a representative γ – γ ′ microstructure. Applied to CM 247 LC, the framework yielded grain-scale elastic constants and CRSS values that fall within the expected range for related Ni-based superalloys, while also providing quantified uncertainties. This demonstrates that spherical nanoindentation, when combined with Bayesian inference, offers a robust pathway for establishing grain-scale effective properties in complex multiphase alloys.