6th World Congress on Integrated Computational Materials Engineering (ICME 2022): Multi-Scale Modeling II
Program Organizers: William Joost; Kester Clarke, Los Alamos National Laboratory; Danielle Cote, Worcester Polytechnic Institute; Javier Llorca, IMDEA Materials Institute & Technical University of Madrid; Heather Murdoch, U.S. Army Research Laboratory; Satyam Sahay, John Deere; Michael Sangid, Purdue University
Tuesday 10:30 AM
April 26, 2022
Room: Regency Ballroom AB
Location: Hyatt Regency Lake Tahoe
10:30 AM
First Principles Prediction of Al-Cu, Al-Li and Al-Cu-Li Phase Diagrams: Sha Liu; Wei Shao1; Javier Llorca1; 1Universidad Politécnica de Madrid & IMDEA Materiales Institute
A strategy is presented to predict the phase diagram of metallic alloys by means of first principles calculations in combination with the cluster expansion formalism and statistical mechanics. The ground state phases for each alloy were determined from first principles calculations of the different lattice configurations in the whole compositional range. In addition, the contribution of lattice vibrations to the free energy was included in the cluster expansion by a bond stiffness vs. bond length relationship obtained from the length-dependent transferable force constants. This information was used to fit a cluster expansion Hamiltonian which was used to determine the partition function and thermodynamic grand potential of each phase by means of Metropolis Monte Carlo simulations. Thus, the phase transitions as a function of temperature were ascertained from the thermodynamic grand potential and the Gibbs free energies of the phases. The strategy was applied to determine the phase diagram of Al-Cu, Al-Li, Al-Cu-Li alloys and the computed phase diagrams were compared with the current experimental phase diagrams in the literature. Overall, the calculated phase diagrams were in good agreement with the currently accepted experimental phase diagrams and, moreover, they provided new insights and information that is sometimes missing in the experimental phase diagrams due to the limitations imposed by the kinetics of phase changes. This additional information can be very important to optimize microstructure of these alloys by means of heat treatments.
10:50 AM
Formation of Crystalline Defects in Rapid Solidification: Tatu Pinomaa1; Sami Majaniemi1; Matti Lindroos1; Nikolas Provatas2; Anssi Laukkanen1; 1VTT Technical Research Centre of Finland; 2McGill University
Rapid solidification leads to formation of various crystalline defects, including vacancy trapping, formation of high dislocation densities, formation of metastable pre-precipitates, and gradients and splitting of crystalline orientation. These crystalline defects critically affect material's mechanical properties, and ultimately contribute to more complex material performance features such as high-cycle fatigue resistance. Therefore it is important to understand the formation mechanisms of the aforementioned defects, and how they depend on the solidification conditions and alloying, in order to better predict and control their formation for designing better and more reliable structural materials. To illuminate the formation mechanisms of these microstructural features, we conduct a multiscale modeling analysis consisting of bond order potential based molecular dynamics (MD), phase field crystal (PFC) method, and sequentially coupled thermomechanical phase field - crystal plasticity scheme. We discuss how the atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models.
11:10 AM
Using CASM for Development of Computational Software Tools
: Brian Puchala1; John Thomas2; John Goiri2; Anton Van der Ven2; 1University of Michigan; 2University of California, Santa Barbara
CASM is an open source statistical mechanics software package that automates the construction and first-principles based parameterization of effective Hamiltonians that can be used to calculate finite temperature thermodynamic and kinetic properties of multi-component crystalline materials. CASM can construct cluster expansion effective Hamiltonians of mixed discrete and continuous degrees of freedom, enabling treatment of strain, displacements, magnetic spin, and user defined degrees of freedom. CASM includes a C++ library with modules for crystallography, symmetry analysis, generating and evaluating cluster expansion basis functions, generating input structures for density functional theory (DFT) calculations, and Monte Carlo calculations. CASM includes Python packages for fitting cluster expansion coefficients and managing DFT calculations, and visualizing results. In this talk we will introduce using CASM as a library for developing new computational software tools and provide example use cases.
11:30 AM
Investigation of Liquid-Assisted Void Healing in Solders: Georg Siroky1; Elke Kraker2; Dietmar Kieslinger3; Ernst Kozeschnik4; Werner Ecker2; 1Technical University Vienna / Materials Center Leoben ; 2Materials Center Leoben Forschung GmbH; 3ZKW Electronics GmbH; 4Technical University Vienna
This work discusses a framework for modelling liquid-assisted healing in low melting solder alloys. Damage evolves due to inelastic deformation in a unified creep-plasticity framework. The total void volume arises from nucleation and growth of single voids. Nucleation depends on the stress triaxiality and initial nucleation sites. The void growth equation includes a creep and plastic growth term to account for a general unified model. The size dependency of void healing is modelled by means of a void collective, which introduces the void size distribution. The size evolution of a void in a locally liquid medium is given by the Rayleigh-Plesset equation. The healing model combines physically motivated variables, such as liquid viscosity, surface tension, liquid- and void pressure. Furthermore, microstructural parameters, such as e.g. permeability or liquid film thickness, obtained from X-ray tomography images are also included. The sensitivity of healing with respect to model parameters is discussed.