Understanding Shock Propagation and Structure in High Entropy Alloys Using Moving Window Concurrent Atomistic Continuum Method
Abstract
High entropy alloys (HEAs) comprise five or more primary elements in equiatomic or near equiatomic composition. HEAs can exhibit excellent high-temperature stability, mechanical properties, and resistance against oxidation and corrosion; making them promising materials for many engineering applications. HEAs also serve as promising candidates as armors in shock applications. While the quasi-static behavior of HEAs has received some attention recently, the high strain rate (HSR) response of HEAs and the role of microstructure remains relatively unexplored. Through this short term innovative research (STIR) project, the PI aims to study shock propagation and shock structure within HEAs. Specifically, the PI will study the evolving shock front structure and defect generation in face centered cubic (FCC) Cantor (CoCrFeMnNi) alloy and its subset FeCrNi. Cantor alloy was amongst the first HEAs that exhibited good tensile properties. Over the past few years, Cantor alloy and their subsets have been well studied under quasi-static loading and to some extent under HSR loading using plate impact experiments. While recent plate impact studies on Cantor subsets have revealed the importance of microstructure in shock induced defect evolution, specific questions such as shock front structure and mechanisms of defect evolution remain unanswered. In this work, the PI will leverage the moving window (MW) formulation of the concurrent atomistic continuum (CAC) method to study shock propagation and evolving shock structure in HEAs. The MW-CAC method was developed by the PI to track a moving shock wave within a moving domain of atomistic resolution embedded in a finite element region of continuum level resolution. This approach enables studying shock propagation in a much larger domain for a much longer time as compared to typical purely atomistic methods such as molecular dynamics (MD). Recently, the CAC method was extended to study multicomponent alloys such as HEAs using the A-atom approach. This work will incorporate the A-atom approach in MW-CAC framework to study shock front evolution in HEAs. The work will be divided into two tasks to be accomplished within a 9-month period by the PI and one graduate student. This work will a) enable development of validated and verified A-atom interatomic potentials which are critical for multiscale modeling of random alloys such as FeNiCr and CoCrFeMnNi, b) systematically develop and verify a 2D concurrent domain with random alloy in the atomistic region and A-atoms in the continuum region, and c) perform and validate 2D MW-CAC shock simulations on single crystal NiCrFe and CoCrFeMnNi to obtain anisotropic equation of state (EOS) parameters and study evolving shock structure. This work will also result in information critical for future studies focused on understanding the interaction of shock waves with microstructure (grain boundaries and phase boundaries), shock induced defect generation, role of nanoscale heterogeneities in HSR response, and shock scattering in HEAs.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 19, 2023
- Source ID
- W911NF2310120
Entities
People
- Vinamra Agrawal
Organizations
- Army Contracting Command
- Auburn University
- United States Army