Advances in Multi-Principal Elements Alloys X: Structures and Modeling: Structures and Modeling III
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Chiao Tung University; Jennifer Carter, Case Western Reserve University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; Gongyao Wang, Alcoa Technical Center
Tuesday 8:00 AM
March 1, 2022
Room: 251B
Location: Anaheim Convention Center
Session Chair: Chelsey Hargather, New Mexico Institute of Mining and Technology; Seungha Shin, University of Tennessee
8:00 AM
First-principles-based High-throughput Prediction of the Phase Stability of Refractory Complex Concentrated Alloys: Zhaohan Zhang1; Mu Li1; John Cavin1; Katharine Flores1; Rohan Mishra1; 1Washington University in St.Louis
The ability to predict the composition- and temperature-dependent stability of refractory complex concentrated alloys (RCCAs) is vital to the design of high-temperature structural alloys. We propose that pairwise mixing enthalpies are a key descriptor for predicting the formation enthalpy of multicomponent solid solutions and apply it to screen over 20,000 compositions. We develop a database that contains the pairwise mixing enthalpies of 17 refractory elements with density-functional-theory (DFT) calculations and use these data to fit thermodynamic models that accurately predict the mixing enthalpies of BCC RCCAs. By combining the enthalpy models with DFT-calculated intermetallic enthalpies from the Materials Project database and using convex hull analyses, we can predict the ground-state phase given alloy composition and temperature. The predictions in NbTiZr-V-(Mo, Ta, Cr) systems agree well with experimental observations. Finally, we use this model to predict phase evolution in NbVZr-Tix (0 < x < 1), which are confirmed using laser processing.
8:20 AM Invited
First-principles Exploration of Diffusion Activation Energy in CoCrNi and CoCrFeNiMn High-entropy Alloys, with Comparison to Creep Activation Energy: Christopher Lafferty1; Chelsey Hargather1; 1New Mexico Institute of Mining and Technology
High entropy alloys (HEAs) are potential candidates for high performance engineering material applications. Creep is permanent, time-dependent inelastic deformation under applied stress, and is often the failure mechanism for structural engineering alloys in service applications. Diffusion behavior is an important contribution to secondary creep behavior. In the present work, first-principles based calculations using density functional theory (DFT) are used to analyze activation energy for diffusion in the CoCrFeNiMn alloy and its constituent ternary systems. The relationship between creep activation energy and diffusion activation energy in well studied systems, such as CoCrNi, are explored. Special quasi-random structures (SQS) are employed, and complications related to structural complexity are discussed. Results are compared to known literature where available, and the importance of the calculations for novel alloy design are discussed.
8:40 AM Invited
Experimental, Theoretical, and Numerical Study for Dynamic Strain Aging in HfNbTaTiZr High-entropy Alloys: Yooseob Song1; Weidong Li2; Shuying Chen3; Ko-Kai Tseng4; Jien-Wei Yeh4; Peter K. Liaw2; 1University of Texas Rio Grande Valley; 2The University of Tennessee, Knoxville; 3Yantai University; 4National Tsing Hua University
In the present work, a systematic investigation of the mechanics of refractory high-entropy alloys with a focus on dynamic strain aging (DSA) is carried out through experimental, theoretical, and numerical approaches. The samples of single-phase body-centered cubic HfNbTaTiZr refractory high-entropy alloys are fabricated through an arc-melting process and tested at a wide range of temperatures to demonstrate the presence of dynamic strain aging. A new constitutive model is developed, considering several important strengthening mechanisms in this type of alloys, including lattice distortion and dynamic strain aging. Correspondingly, the finite element algorithm for the developed model is also presented in the current work via writing a user-defined subroutine. The proposed constitutive model and the corresponding finite element algorithm are validated using the experimental data. The mechanics of these alloys is further studied, employing the validated theoretical model and numerical algorithm.
9:00 AM Invited
Multiscale Dynamics of the Oxide Scale in High-entropy Alloys: Indranil Roy1; Jhalak2; Ganesh Balasubramanian1; Pratik Ray2; 1Lehigh University; 2Indian Institute of Technology Ropar
Oxidation of high-entropy alloys(HEAs) is a complex phenomenon involving a large number of competing oxides and spinels. Often, thermodynamically stable scales are preceded by multiple (transient) kinetically favored oxides. Assessment of the dynamics of the oxide scale requires prior knowledge of diffusivities of ionic species through the oxide, as well as the reactions occurring at the scale/alloy interface. In this talk, we shall present a model for the oxidation of alumina and chromium forming HEAs. We use Molecular Dynamics (MD) simulations to estimate the ionic diffusivities in the oxide scale. The anionic diffusion of oxygen is simulated by providing vacancy in the oxygen cites of oxide structures and calculating the mean square displacement (msd) of oxygen atoms after providing sufficient time for equilibration at the oxidation temperature. The slope of the msd with varying time at different temperatures provides the diffusivity and pre-exponential factor that matches with the experimental data.
9:20 AM Break
9:40 AM Invited
Developing Interatomic Potentials for High Entropy Alloys: Diana Farkas1; Alfredo Caro2; 1Virginia Polytechnic Institute; 2George Washington University
We discuss the development of Embedded Atom Method (EAM) model interatomic potentials is presented to represent a high entropy alloy with five components. The set is developed to resemble but not model precisely FCC near equiatomic mixtures of FCC complex alloys. The individual components have various atomic sizes and the heats of mixing of all binary equiatomic random FCC mixtures are also varied. We discuss cases that predict the random equiatomic FCC quinary mixture to be stable with respect to phase separation or ordering as well as cases where the precipitation of ordered phases is expected. The talk will discuss examples of the use of the potentials to better understand the role of compositional complexity in the mechanical and radiation resistance response of these complex alloys.
10:00 AM
Atomistic Modeling of Vacancy Concentration and Tracer Diffusion in Ni-CoCrFeMn Alloys
: Daniel Utt1; Karsten Albe1; 1Technische Universität Darmstadt
We explore the concentration dependent diffusional properties of multi-principle element alloys (MPEAs) in the prototypical Cantor (CoCrFeMnNi) system. Here, we aim to understand the effects of composition and chemical inhomogeneity on the equilibrium vacancy concentration and resulting tracer diffusivity. We study the equilibrium vacancy concentration in various (CoCrFeMn)xNi1-x alloys by lattice Monte Carlo (MC) simulations. Over 80,000 calculated vacancy formation energies yield statistical distributions, which are used in MC simulations to assess the effect of the configurational entropy on the vacancy concentration. Using a similar approach, the vacancy migration energy distributions are calculated for the same (CoCrFeMn)xNi1-x alloys. These are used as input for a novel kinetic MC model to tackle the chemical complexity in MPEAs. From this model we can obtain tracer diffusivities and tracer correlation factors for all atomic species and sample compositions.
10:20 AM Invited
Computational Study of Thermodynamic and Thermoelectric Properties of Al-Co-Cr-Fe-Ni and Al-Cu-Fe-Mn-Ni High-entropy Alloys: Md Abdullah Al Hasan1; Seungha Shin1; Xuesong Fan1; Peter Liaw1; Dustin Gilbert1; 1University of Tennessee
High-entropy alloys (HEAs) have been of great interest as novel types of alloys because of their unique microstructures and adjustable properties. However, their large configurational space has imposed challenges on the prediction of properties and material design. Computational approaches enable us to effectively study various properties of HEAs, addressing atomic details under systematically controlled conditions. In this presentation, we will introduce our recent computational studies on thermodynamic and thermoelectric properties of Al-Co-Cr-Fe-Ni and Al-Cu-Fe-Mn-Ni HEAs. We investigated these properties of HEAs with varied compositions and short-range orders, using first-principles calculations, molecular dynamics, and semi-classical Boltzmann transport theory. In addition, to effectively analyze a large size of data, we used modern data analytics, including correlation analysis and machine learning. Through this research, we have identified the effects of Al contents and short-range order on thermoelectric performance and thermodynamic properties in AlxCoCrFeNi and studied the thermodynamic properties of various structures of AlCuFeMnNi.