High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond II: Theory and Modeling II
Sponsored by: TMS Alloy Phases Committee, TMS Mechanical Behavior of Materials Committee
Program Organizers: Michael Gao, National Energy Technology Laboratory; Xingbo Liu, West Virginia University; Peter Liaw, University of Tennessee; Jian Luo, University of California, San Diego; Yiquan Wu, Alfred University; Yu Zhong, Worcester Polytechnic Institute; Mitra Taheri, Johns Hopkins University; Amy Clarke, Los Alamos National Laboratory
Wednesday 2:00 PM
October 20, 2021
Room: B131
Location: Greater Columbus Convention Center
Session Chair: Stefano Curtarolo, Duke University
2:00 PM Invited
To Mix, or not to Mix: Progresses in Entropy Descriptors: Stefano Curtarolo1; 1Duke University
Critical understanding of large amount of data leads to new descriptors for discovering entropic materials. The presentation illustrates the ladder of disorder descriptors including the ideal and spectral scenarios and the LTVC method for miscibility gaps.
2:30 PM Invited
Development of Interatomic Potentials for Highly Concentrated/Entropy-stabilized Systems: Ridwan Sakidja1; Andrew Duff2; Bikash Timalsina1; Tyler McGilvry-James1; 1Missouri State University; 2Daresbury Laboratory
We presented a statistically driven, high-entropy-based approach to develop interatomic-potentials designed for high-entropy and concentrated systems. By utilizing the Reference-Free MEAMFIT (RF-MEAMFIT) potential parameterization code, we sampled energy, force, and stress data extracted from the ab-initio molecular dynamics (AIMD) simulations on the HEAs. The method allows us to include samplings from additional compositions, within the vicinity of that of HEAs, to optimize the interatomic potentials further toward the concentrated alloys such as advanced Ni-based alloys. The approach can also be utilized to develop interatomic potentials designed for advanced ceramics including high-entropy stabilized diborides. The supports from NETL-DOE Grant No. FE0031554 (Crosscutting Research Program) and NSF Grant No. 1902069 (Advanced Manufacturing Program) are gratefully acknowledged.
2:50 PM Cancelled
First-principles Predictions of Chemical Short-range Order in High Entropy Alloys: Michael Widom1; 1Carnegie Mellon University
Interaction preferences among different chemical species create short-range chemical order in even in nominally disordered high temperature phases. These interactions can even drive order-disorder transitions and phase separation as temperature is lowered. This talk will present hybrid Monte Carlo/molecular dynamics simulations, and calculations that incorporate short-range order within the Coherent Potential Approximation, in order to identify patterns of ordering in body-centered cubic multicomponent alloys.
3:20 PM Break
3:40 PM Invited
Temperature-dependent Configurational Entropy Calculations for Refractory High-entropy Alloys: Chiraag Nataraj1; Axel van de Walle1; Amit Samanta2; 1Brown University; 2Lawrence Livermore National Lab
The cluster expansion formalism for alloys is used to construct surrogate models for three refractory high-entropy alloys (NbTiVZr, HfNbTaTiZr, and AlHfNbTaTiZr). These cluster expansion models are then used along with Monte Carlo methods and thermodynamic integration to calculate the configurational entropy of these refractory high-entropy alloys as a function of temperature. Many solid solution alloy design guidelines are based on the ideal entropy of mixing, which increases monotonically with N, the number of elements in the alloy. However, our results show that at low temperatures, the configurational entropy of these materials is largely independent of N, and the assumption described above only holds in the high-temperature limit. This suggests that alloy design guidelines based on the ideal entropy of mixing require further examination.
4:00 PM Invited
Phase-field Modelling of Transformation Pathways and Microstructural Evolution in MPEAs (Multi Principal Element Alloys): Kamalnath Kadirvel1; Jacob Jensen1; Zachary Kloenne1; Rajarshi Banerjee2; Hamish Fraser1; Yunzhi Wang1; 1Ohio State University; 2University of North Texas
Multi Principal Element Alloys with multiple phases have very good structural and functional properties. The recently developed refractory MPEA, AlMo0.5NbTa0.5TiZr, shows an interesting microstructure with ordered phase (B2) being the matrix and disordered phase (A2) being the precipitate, unlike the conventional Ni-based superalloys where the ordered phase (𝛾′) is the precipitate and the disordered phase is the matrix (γ). It becomes crucial to understand the transformation pathway leading to this microstructure in order to tailor the microstructure for specific engineering applications. We proposed a transformation pathway for the MPEA, AlMo0.5NbTa0.5TiZr, which has superior mechanical properties, and employed phase-field method to simulate the microstructural evolution which follows the pathway. The simulation results are compared with experimental observations. We also explored the role of modulus mismatch between the phases and the volume fraction of B2 phase in determining the topology of the microstructure. This work is supported by AFOSR under grant FA9550-20-1-0015.
4:20 PM
Now On-Demand Only: Atomistic Simulations of the Structure and Mechanical Properties of Grain Boundaries in High Entropy Alloys: Fadi Abdeljawad1; 1Clemson University
Owing to the non-dilute compositions of their elements, High entropy alloys (HEAs) exhibit unique combinations of properties that are not typically encountered in conventional alloys. Motivated by recent experiments on HEAs demonstrating that grain boundaries (GBs) act as nucleation sites for deformation twinning, herein, we leverage atomistic simulations to examine the role of GBs in the deformation behavior of the equiatomic CoCrFeMnNi HEA (i.e., Cantor alloy). A series of atomistic Cantor alloy bi-crystals with symmetric twist GBs are constructed, and then deformed in tension. Simulation results reveal that plastic deformation proceeds by the nucleation of partial dislocations from GBs, which then grow in the bulk crystals with further loading leaving behind stacking faults. Variations in the nucleation stress exist as function of the twist angle. Our results provide future avenues to explore GBs as a microstructure design tool to develop HEAs with tailored properties.