Matching time and spatial scales of rapid solidification: dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations. (5th December 2017)

• Record Type: Journal Article
• Authors: Perron, Aurelien; Roehling, John D; Turchi, Patrice E A; Fattebert, Jean-Luc; McKeown, Joseph T
• Is Part Of: Modelling and simulation in materials science and engineering. Volume 26:Number 1(2018)
• Publication Date: 2017-12-05
• Subjects: rapid solidification -- dynamic TEM -- phase-field -- CALPHAD -- Cu–Ni alloys; Materials -- Mathematical models -- Periodicals; Matériaux -- Modèles mathématiques -- Périodiques; Materials -- Mathematical models; Periodicals; 620.00113
• DOI: 10.1088/1361-651X/aa9a5b
• Languages: English
• ISSNs: 0965-0393

Abstract

Abstract: A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu–Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid–liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu–Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying from ∼0.1 to ∼0.6 m s −1 . After an 'incubation' time, the velocity of the planar solid–liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Finally, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid–liquid interface velocity) were consistent at similar time ( μ s) and spatial scales ( μ m).