Co-Based Superalloy Morphology Evolution: A Phase Field Study Based on Experimental Thermodynamic and Kinetic Data
Carelyn E. Campbell, Ursula R. Kattner, Jonathan E. Guyer, James A. Warren, Wenkun Wu, Peter Voorhees, Olle Heinonen
Cobalt-based superalloys with gamma/gamma prime microstructures off er great promise as candidates for next-generation high-temperature alloys for applications, such as turbine blades. It is essential to understand the thermodynamic and kinetic factors that influence the microstructural evolution of these alloys in order to optimize the alloy compositions and processing steps with a goal to improve their coarsening, creep and rafting behavior. We are using a continuum phase fi eld approach to study the diffusion process and to predict the equilibrium shapes of Co-Al-W gamma prime precipitates. In order to obtain quantitatively predictive capabilities, we extract chemical free energies for the gamma/gamma prime phases based on CALPHAD thermodynamic data and diff usion mobilities for Co alloys based on CALPHAD kinetic data. We also use experimental or fi rst-principles data for other quantities, such as mini t strain and interface information, for the parameterization of our model. A particular focus of our study is to understand how diff erent energy balances, mis t strain and kinetics a ffect the coarsening and rafting behavior of gamma prime precipitates, and the sensitivity of the final precipitate shape to materials parameters. We find that the equilibrium shape of the precipitate results from a delicate competition between chemical, interfacial, and elastic energies, and it is very sensitive to changes in model parameters. We examine how modeling input parameters aff ect the equilibrium shape of precipitates and relate these parameters to experimentally available values.
, Kattner, U.
, Guyer, J.
, Warren, J.
, Wu, W.
, Voorhees, P.
and Heinonen, O.
Co-Based Superalloy Morphology Evolution: A Phase Field Study Based on Experimental Thermodynamic and Kinetic Data, Acta Materialia, [online], https://doi.org/10.1016/j.actamat.2022.117978, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933370
(Accessed December 10, 2023)