Using “Microstructure Informatics” to Understand Abnormal Grain Growth Factors in Powder Metallurgy Ni-Based Superalloys

Advanced electron backscatter diffraction (EBSD) and electron dispersive spectroscopy (EDS) techniques were used to systematically quantify meso-scale microstructural descriptors in an advanced powder processed polycrystalline Ni-base superalloyNi-base superalloys containing elevated levels of refractory alloying additions. The microstructural changes of the alloy as a function of effective strain were tracked and related to the subsequent heat-treated microstructuresMicrostructure. This emerging field of “microstructure informaticsMicrostructure informatics” extends beyond the conventionally used metrics of grain and precipitatePrecipitates sizes and distributions. Due to the multidimensional nature of the data, manual microstructure characterizationMicrostructure characterization becomes virtually impossible, especially when a multitude of different material states must be considered. This motivated the development of an automated microstructure characterizationMicrostructure characterization procedure, which extracts useful geometric, crystallographic, and chemical microstructureMicrostructure features through a batch process. These features provide a level of microstructureMicrostructure detail that has not traditionally been demonstrated at a statistically significant scale capable of effectively capturing the level of intrinsic heterogeneity that is present in polycrystalline Ni-base superalloysNi-base superalloys. In this study, microstructural descriptors from the deformed material were evaluated and used to understand the grain growthGrain growth response during super-solvus heat treatmentHeat treatment. Compared to traditional qualitative and semi-quantitative approaches for characterizing microstructuresMicrostructure, the innovative methodology used in this investigation provide insightful, quantitative microstructureMicrostructure metrics that lead to the generation of new knowledge and scientific understanding.