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Suman Chabri

Publications and source records attributed to Suman Chabri.

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Information Entropy Based Crystal Structure Prediction of Chemically Disordered Alloys via Graph Convolutional Neural Networks

The phase prediction of chemically disordered alloys poses a significant computational challenge due to the combinatorial complexity of such materials. The high-throughput compositional exploration of chemically disordered alloys, including high-entropy alloys, requires an approach to efficiently explore the potential energy landscape of such complex materials. Additionally, a metric to quantify the potential energy landscape explored for phase prediction of the compositions needs to be defined. We propose an information-theoretic approach to phase prediction in chemically disordered alloys in the present work. We demonstrate the applicability of alchemical Monte Carlo sampling using an efficient Graph Convolutional Neural Network-Based machine learning model. We additionally demonstrate the applicability and limitations of the Bond Disproportion Vector (BDV) as a low-computational-cost descriptor and benchmark it against the state-of-the-art Smooth Overlap of Atomic Positions (SOAP) descriptor. We show the applicability of an information entropy-based metric for the phase prediction of binary (CoNi, MoW, FeNi and TaW), ternary (CoCrNi, CrFeNi), quaternary (CoCrFeNi) and quinary ($\mathrm{Al_x(CoCrFeNi)_{1-x}}$) alloys. Information entropy-based phase prediction can be applicable in challenging cases where conventional approaches are not feasible.

cond-mat.mtrl-sci

Edge Dislocation Mediated Anomalous Charge Transfer in Face Centered Cubic High Entropy Alloys

Charge transfer in concentrated alloys governs their structural stability and functional response, and can be strongly perturbed by lattice defects. In high-entropy alloys, the interaction between edge dislocations and volume misfit plays a central role in solid-solution strengthening models; however, the influence of dislocations on the local charge transfer has not been explicitly investigated. In this work, large-scale ab initio calculations are employed to examine the dislocation-mediated charge transfer in CoNi, CoCrNi and CoCrFeMnNi alloys. The calculations reveal an anomalous charge redistribution near edge dislocation cores, including deviation from the conventional electronegativity trend. The observed behavior is shown to originate from collective electronegativity equalisation effects rather than simple pairwise atomic interactions. Furthermore, the asymmetric atomic volume response within the compressive and tensile regions of the dislocation field is rationalised in terms of anomalous magneto-volume fluctuations. These results establish a direct coupling between dislocation-induced electronic redistribution and local volumetric response in chemically complex alloys. The demonstrated coupling between dislocation-mediated charge transfer and atomic volume fluctuations provides a pathway toward electronically informed solid-solutions strengthening models and defect-aware alloy design strategy for chemically complex alloys. These findings further suggest that local electronic redistribution near dislocation-cores can play a critical role in governing the deformation behavior and defect-enbergetics in high-entropy alloys.

cond-mat.mtrl-sci