Abstract Solute segregation at grain boundaries (GBs) changes mechanical properties of high-temperature materials. For example, it is known that a trace amount of boron added to nickel-based superalloys segregates at GBs and improves the creep rupture strength of the alloys, although its strengthening effect has not yet been quantified. Recently, it has been demonstrated that the computational method combining the Hillert’s grain-boundary phase model and CALPHAD (calculation of phase diagram) database is effective for predicting GB chemistry (equilibrium composition of random high-angle GBs) in multicomponent alloys. It has been shown that this method can predict the GB segregation of molybdenum and boron in nickel-based superalloys, the GB segregation of boron and phosphorous in an austenitic stainless steel, and GB segregation of nickel and manganese in a high-entropy alloy. By using this method, the GB chemistry of commercial polycrystalline nickel-based superalloys was computed, and its correlation with the creep rupture strength of the alloys was examined. A weak positive correlation was confirmed between the GB concentration of boron and the creep rupture strength. Furthermore, a linear prediction model of the creep rupture strength of nickel-based superalloys was proposed, where the computed GB concentrations of solute elements were used as explanatory variables. The trained model has a sufficient degree of prediction accuracy and clearly shows the importance of regulating the GB concentration of boron for improving the creep rupture strength of nickel-based superalloys. Grain Boundary Segregation and Creep Pupture Strength of High-Associate Professor, Department of Materials Science and Engineering, Session 2 ｜Yuhki Tsukada is an associate professor at Department of Materials Science and Engineering, Nagoya University, Japan. He received Bachelor’s, Master’s and Doctoral degrees in Engineering from Nagoya University, Japan in 2007, 2009 and 2011, respectively. He joined Nagoya Institute of Technology, Japan as an assistant professor in 2011. He moved to Nagoya University, Japan as an assistant professor in 2015, and was promoted to an associate professor in 2016. His main research area is the phase-field modeling of microstructure evolution during solid-state phase transformations. He is also interested in data assimilation methods that combine experimental data with a microstructure simulation model. He is serving as a subject editor of Science and Technology of Advanced Materials, and an associate editor of Science and Technology of Advanced Materials: Methods. NIMS Award Symposium 2023Temperature MNagoya University, Japan Yuhki Tsukada High-temperature Materialsaterials Invited Talk S2-3 31
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