Filling the Material Property Data Gaps with CALPHAD Based Predictions for More Accurate ICME Simulations

The publication by the National Academies in 2008 on Integrated Computational Materials Engineering (ICME) highlighted the need for better multiscale materials modeling to capture the process-structures-properties-performance of a material. To describe these links we need models, but many of these models need data, specifically materials data, a lot of which is often not known.

Material properties and behavior are strongly dependent on the chemical composition of the material and variations in processing conditions. Handbook data typically exists only for the most common materials and does not capture differences arising from composition variations or processing conditions. Where this knowledge is missing, tools are needed to fill the gaps and make predictions of material behavior throughout the materials life cycle.

CALPHAD, allows for the prediction of the thermodynamic properties and phase stability of an alloy, under stable and metastable conditions. Additionally, the CALPHAD approach can also be extended to model atomic mobilities and diffusivities in a similar way. By combining thermodynamic and mobility data, kinetic reactions during solidification and subsequent heat treatment processes can be simulated. Recently, CALPHAD based models for thermophysical properties such as thermal/electrical conductivity, viscosity, and surface tension have also been developed. This enables composition and temperature dependent data to be incorporated into finite element and computational fluid dynamics simulations. Such simulations provide better understanding of the material, processing route, and service conditions on resultant structure properties and performance.

This presentation will highlight new developments and give examples where CALPHAD tools have been applied to aerospace materials in the areas of additive manufacturing, coatings and alloy development.