|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Phase Transformations and Microstructural Evolution
||Understanding the Initial Development of γ/γ' Microstructures in Cobalt-based Superalloys
||Andrea Jokisaari, Eric Lass, Peisheng Wang, Peter Voorhees, Olle Heinonen
|On-Site Speaker (Planned)
Novel γ/γ' cobalt-based superalloys are promising potential replacements for nickel-based superalloys. Experimental investigations have largely targeted creep behavior and γ' coarsening, while theory has mostly focused on the thermodynamics of increasingly complex alloy compositions. However, relatively little work has been performed to understand the initial development of the γ/γ' microstructure. While it is generally assumed that γ' forms via nucleation and growth, data from atom probe investigations of as-quenched and briefly annealed samples hint at spinodal decomposition. We take a combined theory/experiment approach to study the formation of γ' from the solutionized state in the Co-Al-W system, including CALPHAD-based thermodynamic modeling, the phase field method, and TEM characterization. This approach will shed light on thermodynamic and kinetic aspects, such as the free energy landscape and the change in lattice parameters due to changing solute concentrations, that control the initial phase transformation and the development of the characteristic γ/γ' microstructure.
||Planned: Supplemental Proceedings volume