Phase Transformations and Microstructural Evolution: Modeling and Simulations
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Phase Transformations Committee
Program Organizers: Mohsen Asle Zaeem, Colorado School of Mines; Ramasis Goswami, Naval Research Laboratory; Saurabh Puri, VulcanForms Inc; Eric Payton, University of Cincinnati; Megumi Kawasaki, Oregon State University; Eric Lass, University of Tennessee-Knoxville

Wednesday 2:00 PM
March 2, 2022
Room: 255B
Location: Anaheim Convention Center

Session Chair: Vahid Tari, ATI

2:00 PM  
Atomistic Modeling of η-Fe2C Carbide Precipitation Kinetics in Fe-C System: Helena Zapolsky1; Felix Schwab1; Renaud Patte1; Gilles Demange1; Armen Khachaturyan2; 1Cnrs, Gpm, Umr 6634; 2Rutgers University NJ, USA
     Carbon steels are in widespread use in industry due to their beneficial combination of properties such as strength and hardness.These steels are Fe-C interstitial solid solution based on the low temperature bcc and high temperature fcc phase. Among its various forms, martensite obtained by quenching the fcc austenite is the one with the highest strength. However, iron-carbon martensite is not stable at room temperature but undergoes aging resulting in a re-distribution of carbon atoms, which form carbon-rich zones. 𝜂-Fe2C carbide is transition compound which observed in martensite during the initial stages of tempering. It crystal structure is well documented , however, precipitation kinetics pathway continues to be an open question. In this study, the Atomic Density Function theory has been employed to model the low temperature kinetics of carbon redistribution in martensite. Based on the simulation results, the transformation path between freshly formed martensite and 𝜂-Fe2C carbide is discussed.

2:20 PM  
An Molecular Dynamics Simulation Study of the Interface Migration Mechanism during B2-B33 Transformation in Ni50Zr50 Alloy: Huajing Song1; M.I. Mendelev2; 1Los Alamos National Laboratory; 2Ames Laboratory
    Molecular dynamics simulations using a Finnis-Sinclair potential for a stoichiometric com- pound Ni50Zr50 binary alloys were performed to determine the atomic mechanisms taking place during the migration of a B2/B33 interface. The free energy difference as a function of temperature between the B2 and B33 phases, which provided the driving force for boundary motion, was determined by a thermodynamic integration procedure. The boundary mobility was obtained and followed an Arrhenius behavior with an activation energy of 88 ± 9 kJ mol^−1, such value is much lower when comparing with other single element phase transformation. The element ordering in the stoichiometric compounds increased the difficulty for atom crossing the interface, which inflected in a higher activation energy comparing with the single element system. The interface growth mechanisms identified here may provide important insights into the mobility of more general incoherent interphase boundaries in stoichiometric compound binary alloys systems.

2:40 PM  
Modeling of Phase Transformation Kinetics in Ti-6Al-4V Alloy during Additive Manufacturing: Adrian Boccardo1; Xinyu Yang2; Damien Tourret3; Javier Segurado4; Mingming Tong2; Seán Leen2; 1Mechanical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland. I-Form Advanced Manufacturing Research Centre, National University of Ireland Galway, Galway, Ireland. IMDEA Materials Institute, Madrid, Spain; 2Mechanical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland. I-Form Advanced Manufacturing Research Centre, National University of Ireland Galway, Galway, Ireland; 3IMDEA Materials Institute, Madrid, Spain; 4IMDEA Materials Institute, Madrid, Spain. Universidad Politécnica de Madrid (UPM), Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos, Madrid, Spain
    Additive Manufacturing allows building metallic components of great topological complexity. However, the successive deposition and melting of material layers involves a convoluted thermal cycling with high heating and cooling rates, gradually decreasing as layers are added, which often results in multiple concurrent phase transformations. In this work, we study the phase transformations occurring in a Ti-6Al-4V alloy during fusion-based additive manufacturing (e.g. selective laser melting). These transformations include the transformation from a β phase into a metastable α’ martensite due to the rapid cooling after the layer deposition, followed by the α’ martensite decomposing (partially or totally) into an α+β structure during the cyclic temperature evolution. We combine different models (e.g. Avrami-based and phase-field) to simulate these solid-state transformations, paying special attention to the kinetics of martensite decomposition. Our simulation results are compared to experimental measurements to evaluate and discuss the accuracy, performance, and limitations of the models.

3:00 PM  
Phase Field Simulations of Microstructural Evolution Using the PRISMS-PF Framework: David Montiel1; Stephen DeWitt1; John Allison1; Katsuyo Thornton1; 1University of Michigan
    The PRISMS-PF framework is a powerful, massively parallel finite element code for conducting phase-field simulations of microstructural evolution. This framework features a simple interface for solving customizable systems of partial differential equations of the type commonly found in phase-field models. The framework’s performance is enabled by its use of a matrix-free finite element method for explicit time integration, advanced adaptive meshing, and multi-level parallelization. We demonstrate PRISMS-PF adaptability to simulate a wide variety of phenomena; many of which are featured in its 27 pre-built application modules, including recently released modules to simulate corrosion, alloy solidification and static recrystallization. We also introduce new added features to enhance its performance, ease of use, and integration with other computational tools. These features include a new implicit solver, a series of video tutorials and integration scripts with the PRISMS-Plasticity crystal plasticity finite element framework, and the Materials Commons information repository.

3:20 PM Break

3:40 PM  
A Strain-induced Austenite to Martensite Transformation Kinetics Law Implemented in Crystal Plasticity for Predicting Strain-path Sensitive Deformation of Stainless Steels: Marko Knezevic1; Zhangxi Feng1; 1University of New Hampshire
    Austenite to martensite phase transformation during deformation in stainless steels is primarily strain-induced featuring an intermediate epsilon phase. The transformation involves partial dislocations forming shear bands of epsilon phase, which after intersecting with other shear bands give rise to alpha phase. A phase transformation kinetics law reflecting the deformation mechanism physics of transformations is implemented in an elasto-plastic self-consistent crystal plasticity model for predicting the evolution of martensite phases and mechanical properties. The model is calibrated as a standalone code using a comprehensive set of experimental data for 304L and 316L consisting of stress-strain curves and phase fractions during tension and compression at different temperatures and strain rates. The model is then used in finite elements to predict the evolution of phases, texture per phase, and geometrical changes during several deformation paths including tension, compression, and impact. The implementation and insights from these predictions are discussed in this paper.