Development of an Integrated Computational Materials Engineering-based property model library (application example of single crystal nickel superalloy design)

For thirty years CALPHAD has been applied to the accelerated development of new alloys. Over this period, the approach has evolved from modeling the underlying thermodynamics and phase equilibria of multicomponent alloys, to simulating diffusion controlled phase transformations and precipitation kinetics. CALPHAD is an important foundation to the Integrated Computational Materials Engineering (ICME) based approach, but further work is required to maximize the benefit of this integrated discipline.  This presentation describes ongoing work in support of ICME, for the development of property model libraries and also more flexible output options, such as 2D contour plots as a function of composition and processing variables.

As an application (illustrative) example, an overview of the computational design of a low-Re, high-performance advanced nickel single crystal superalloy (“QT-SX”) will be presented.  Liquid buoyancy modeling allowed for optimization of alloy processability (i.e., freckling, high/low angle boundary (HAB/LAB) formation, grain nucleation, and shrinkage/porosity), while modeling of precipitate (γ’) phase fraction and coarsening rate allowed for optimization of creep and oxidation resistance.  The design process was based on a systems-based approach that included modelling, targeted experimental validation and characterization, and accelerated scale-up and manufacturing.  Data from sub-scale and prototype-scale single crystal castings will be presented.