Chemo-elastic phase-field simulation of the cooperative growth of mutually-accommodating Widmanstätten plates

• Published in: Journal of alloys and compounds 2018-10, Vol.767, p.1141-1154
• Main Authors: Kubendran Amos, P.G., Schoof, Ephraim, Schneider, Daniel, Nestler, Britta
• Format: Article
• Language: English
• Subjects: Austenite decomposition; Austenitic transformations; CALPHAD; Chemo-elastic transformation; Computer simulation; Curvature; Ferrites; Manufacturing; Multiphase; Organic chemistry; Phase transitions; Phase-field model; Plates (structural members); Scanning electron microscopy; Self-accommodating plates; Steel; Transmission electron microscopy; Widmanstätten ferrite
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.07.138

A comprehensive understanding of the phase transformations is of primary importance to optimize the properties of a material. In the present study, a novel and thermodynamically consistent chemo-elastic multiphase-field model is formulated to simulate phase transformations which yield unique needle-like patterns, referred to as Widmanstätten structure. Owing to the critical role of the curvature in the growth of the Widmanstätten structure, the model is devised to recover the sharp interface solutions, despite the introduction of a diffuse interface. This condition is fulfilled by formulating the chemical and the elastic driving force based on the grand potential density and the mechanical jump conditions, respectively. Additionally, to render a quantitative chemical driving force, parameters from CALPHAD-database (TCFE8) are incorporated. The current work, through the multicomponent multiphase-field simulations, shows that at high temperatures, when the chemical driving force is insufficient to actuate the growth of a plate, the Widmanstätten structure evolves by the co-operative growth of self-accommodating plates. Furthermore, the growth of a single Widmanstätten plate at low temperature is also simulated, and the growth kinetics of the transformations are verified through existing analytical predictions. •A chemo-elastic multiphase-field model is presented.•The model is formulated to efficiently recover the physical laws and sharp interface solutions.•Chemically driven self-accommodating growth of Widmanstätten structure is simulated.•The evolution of the elastic strains which favours such transformations are elucidated.