Computational Thermodynamics and Kinetics: Grain Boundary Properties and Kinetics
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Chemistry and Physics of Materials Committee, TMS: Computational Materials Science and Engineering Committee
Program Organizers: Nana Ofori-Opoku, Canadian Nuclear Laboratories; Eva Zarkadoula, Oak Ridge National Laboratory; Enrique Martinez Saez, Clemson University; Vahid Attari, Texas A&M University; Jorge Munoz, University of Texas at El Paso
Monday 8:30 AM
March 15, 2021
Room: RM 54
Location: TMS2021 Virtual
Session Chair: Reza Darvishi Kamachali, Federal Institute for Materials Research and Testing (BAM); Brandon Runnels, University of Colorado; Ian Winter, Lawrence Livermore National Laboratory; Nana Ofori-Opoku, Canadian Nuclear Laboratories
8:30 AM
Introductory Comments: Computational Thermodynamics and Kinetics: Nana Ofori-Opoku1; 1Canadian Nuclear Laboratories
Introductory Comments
8:35 AM
Extracting and Examining the Grain Boundary Diffusivity Tensor of Hydrogen in Nickel Using Atomistic Simulations: David Page1; Hadley Peay1; Katie Varela1; Oliver Johnson1; David Fullwood1; Eric Homer1; 1Brigham Young University
Grain boundaries have diffusive properties that can vary significantly from the bulk and from other grain boundaries. We detail methods to calculate the full diffusivity tensor for both bulk and grain boundary regions for the diffusion of hydrogen in nickel bicrystals using molecular dynamics simulations. We examine the trends of these tensor components over a range of 100-axis symmetric tilt grain boundaries and explore the meaning of the values as well as their dependence on the atomic grain boundary structure.
8:55 AM Invited
Elastic Interactions in Grain Boundary Phase Transformations: Ian Winter1; Robert Rudd1; Tomas Oppelstrup1; Timofey Frolov1; 1Lawrence Livermore National Laboratory
Grain boundaries influence many properties of engineering materials. Accurate prediction of their structure and possible transitions using atomistic modeling are important for strategies aimed at improving materials properties. Recently there has been a rapid growth in evidence suggesting that materials interfaces can exhibit first-order structural transformations in which the interface properties undergo discontinuous changes. Experiments have linked these transitions to abnormal grain growth, activated sintering and liquid metal embrittlement and raised fundamental questions concerning the atomic structures and kinetic properties of these interface phases. In this work, we model grain boundary phase transformations in tungsten using atomistic simulations. Specifically, we investigate the importance of elastic interactions on the kinetics of grain boundary phase transformations and develop a corresponding elastic theory that can enable the mesoscale modelling of GB phenomena. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
9:25 AM
Atomistic Modeling of Carbon Atom Redistribution in the Fe-C Martensite: Helena Zapolsky1; Felix Schwab1; Gilles Demange2; Frederic Danoix1; Renaud Patte1; Armen Khachaturyan3; 1Cnrs, Gpm, Umr 6634; 2Cnrs-University of Rouen Normandy; 3Rutgers University
The binary Fe–C system is of special importance for iron and steel industry and different stages of tempering kinetics have been investigated in details. However, all these studies do not allow to have a fully understanding of a sequence of structural transformations and atomic structure of transient phases formed at very early stages of tempering kinetics. In this study we employ the Atomic Density Function (ADF) theory to model the low temperature kinetics of carbon redistribution. The obtained solution of the microscopic ADF kinetic equation describes the temporal evolution of C atoms in atomic scale. It automatically describes the C atom reconfiguration in atomic and nano-scale that includes ordering within C atom clusters. The employed atomistic approach makes possible the direct comparison of simulation results with experimental data obtained by Atom Probe Tomography (APT) data.
9:45 AM Invited
Density-based Thermodynamics of Microstructure Defects: Lei Wang1; Reza Darvishi Kamachali1; 1Federal Institute for Materials Research and Testing (BAM)
Systematic microstructure design requires reliable thermodynamic descriptions and phase diagrams of each and all microstructure elements. While such descriptions are well established for most bulk phases, thermodynamic assessment of crystal defects is greatly challenged by their individualistic aspects. In this talk, we present a density-based thermodynamic concept [1] to describe defects based on available bulk thermodynamic data. Here dealing with grain boundaries (GBs), we apply this concept to compute GB (phase) diagram [2]. Applications to segregation engineering of GBs in bulk and nanocrystalline alloys will be presented. We further develop this model to include the effect of elastic interactions due to atom size mismatch and obtain the corresponding GB (phase) diagram for the ternary Al-Cu-Li system. References : [1] Darvishi Kamachali, R. A Model for Grain Boundary Thermodynamics. RSC Adv., 2020, 10, 26728-26741. [2] Wang, L., Darvishi Kamachali, R. Simple Density-based Phase Diagrams for General Grain Boundaries; Submitted.