γ′ Thermodynamic Simulation and Experimental Validation of Phase Stability in Ni-Based Superalloys

Abstract

There is a constant push for higher efficiencies, lower cost, and increased power in power-generating and propulsion gas turbines. In order to meet these requirements, hot section materials with higher temperature capabilities are needed. Ni-base superalloys are selected for these applications. In this study, commercially available and model Ni-based superalloy compositions were simulated with thermodynamic calculations using Thermo-Calc software, which were then experimentally evaluated. Previously, alloy development campaigns have relied heavily on preparing many heats of alloys to examine the effect of various alloying additions and various levels to down-select a single alloy. Methods like PHACOMP have used understanding of partitioning behavior for alloy design. More recent studies have utilized regression analysis of empirical data to inform new alloy design. Physical models can be used to improve upon these methods. The ability to use computational materials science approaches to reduce the number of heats processed in an alloy development program was explored. By validating database sensitivity to compositional changes, future alloy development work can be performed precisely, leading to faster alloy development, validation, and implementation. Model alloys were optimized for phase stability, cost, and density. Continued experimental validation of thermodynamic prediction databases will create a more robust system for alloy property prediction and development.