arXiv subjects

Debashish Sur

Publications and source records attributed to Debashish Sur.

7 recordsLinked to original sources

arXiv2025

Revisiting the Influence of Sn in Cu-Al alloys: A Third Element Effect Enabling Stainless Steel Type Aqueous Passivation Behavior

The influence of Sn alloying additions on the aqueous passivation behavior of Cu-Al alloys was revisited and found to function as a new third element effect in acidified 0.1 M Na2SO4 solution. The role of each element during the process of aqueous passivation was investigated using electrochemical and surface-sensitive ex-situ and in-operando spectroscopic techniques. The connection between passivation and the atomic arrangements of atoms in the solid solution was supported by first principles based cluster expansion calculations and Monte Carlo simulations probing the chemical short-range order in the Cu-Al-Sn system. High purity Sn, like high purity Cu, did not passivate in the test environment, whereas high purity Al formed a passive film with a stable passive current density of 0.01 mA/cm^2. Cu-xAl-Sn solid solution alloys where x greater than 18 at.%, containing less than 3 at.% Sn additions exhibited lower corrosion rates than Cu-xAl alloys, brought by Al(III) and Sn(IV, II) unidentified complex oxides formation on the surface. A strong influence of Sn on Al(III) passivation was observed, i.e., strongly suggesting a third element effect type behavior. Possible governing processes explaining the stainless steel type corrosion behavior are discussed, providing insights for exploring novel synergies in the design of corrosion resistant alloys.

cond-mat.mtrl-sci↗

arXiv2025

Designing Corrosion-Resistant CoCrNi Medium Entropy Alloys via Short-Range Order Modification

Equiatomic CoCrNi medium entropy alloys are known for their unique properties linked to chemical short-range order (CSRO), crucial in both percolation processes and/or nucleation and growth processes influencing alloy passivation in aqueous environments. This study combines extended x-ray absorption fine structure, atomistic simulations, electrochemical methods, x-ray photoelectron spectroscopy, and transmission electron microscopy to explore CSRO evolution, passive film formation, as well as its characteristics in the as-homogenized CoCrNi condition, both before and after aging treatment. Results reveal a shift in local alloying element bonding environments post-aging, with simulations indicating increased Cr-Cr CSRO in 2nd nearest neighbor shells. Enhanced passive film formation kinetics and superior protection of the aged alloy in harsh acidified 3 mol/L NaCl solution indicate improved aqueous passivation correlated with Cr-Cr CSRO. This work establishes a direct connection between alloy CSRO and aqueous passivation in CoCrNi, highlighting its potential for tailored corrosion-resistant applications.

cond-mat.mtrl-sci↗

arXiv2024

An Assessment of Commonly Used Equivalent Circuit Models for Corrosion Analysis: A Bayesian Approach to Electrochemical Impedance Spectroscopy

Electrochemical Impedance Spectroscopy (EIS) is a crucial technique for assessing corrosion of a metallic materials. The analysis of EIS hinges on the selection of an appropriate equivalent circuit model (ECM) that accurately characterizes the system under study. In this work, we systematically examined the applicability of three commonly used ECMs across several typical material degradation scenarios. By applying Bayesian Inference to simulated corrosion EIS data, we assessed the suitability of these ECMs under different corrosion conditions and identified regions where the EIS data lacks sufficient information to statistically substantiate the ECM structure. Additionally, we posit that the traditional approach to EIS analysis, which often requires measurements to very low frequencies, might not be always necessary to correctly model the appropriate ECM. Our study assesses the impact of omitting data from low to medium-frequency ranges on inference results and reveals that a significant portion of low-frequency measurements can be excluded without substantially compromising the accuracy of extracting system parameters. Further, we propose simple checks to the posterior distributions of the ECM components and posterior predictions, which can be used to quantitatively evaluate the suitability of a particular ECM and the minimum frequency required to be measured. This framework points to a pathway for expediting EIS acquisition by intelligently reducing low-frequency data collection and permitting on-the-fly EIS measurements

cond-mat.mtrl-sci↗

arXiv2023

AutoEIS: automated Bayesian model selection and analysis for electrochemical impedance spectroscopy

Electrochemical Impedance Spectroscopy (EIS) is a powerful tool for electrochemical analysis; however, its data can be challenging to interpret. Here, we introduce a new open-source tool named AutoEIS that assists EIS analysis by automatically proposing statistically plausible equivalent circuit models (ECMs). AutoEIS does this without requiring an exhaustive mechanistic understanding of the electrochemical systems. We demonstrate the generalizability of AutoEIS by using it to analyze EIS datasets from three distinct electrochemical systems, including thin-film oxygen evolution reaction (OER) electrocatalysis, corrosion of self-healing multi-principal components alloys, and a carbon dioxide reduction electrolyzer device. In each case, AutoEIS identified competitive or in some cases superior ECMs to those recommended by experts and provided statistical indicators of the preferred solution. The results demonstrated AutoEIS's capability to facilitate EIS analysis without expert labels while diminishing user bias in a high-throughput manner. AutoEIS provides a generalized automated approach to facilitate EIS analysis spanning a broad suite of electrochemical applications with minimal prior knowledge of the system required. This tool holds great potential in improving the efficiency, accuracy, and ease of EIS analysis and thus creates an avenue to the widespread use of EIS in accelerating the development of new electrochemical materials and devices.

cond-mat.mtrl-sci↗

arXiv2023

Why is EXAFS analysis for multicomponent metals so hard? Challenges and opportunities for measuring ordering in complex concentrated alloys using x-ray absorption spectroscopy

Short range order is a critical driver of properties (e.g. corrosion resistance and tensile strength) in multicomponent alloys such as complex concentrated alloys (CCAs). Extended x-ray absorption fine structure (EXAFS) is a powerful technique well suited for quantifying this short range order.Here, we described in detail the characteristics of CCAs that make the already challenging task of analyzing EXAFS data even more difficult. We then illustrate novel paths towards robust and scalable quantitative SRO analysis which will accelerate the scientific understanding and development of CCAs.

cond-mat.mtrl-sci↗

arXiv2023

A High Throughput Aqueous Passivation Testing Methodology for Compositionally Complex Alloys using Scanning Droplet Cell

Compositionally complex alloy systems containing more than five principal elements allow exploring a wide range of compositions, processing, and structural variables with the hope for identifying unique properties. Such opportunities also apply to designing materials for improved corrosion resistance, regulated by a self-healing passive film. Such a rich landscape in reactivity and protectivity demands the search for high-throughput experimental testing workflows to uncover key metrics, indicative of superior properties. In this communication, one such methodology is demonstrated for evaluating passivation performance of a combinatorial library of Al0.7-x-yCoxCryFe0.15Ni0.15 thin film alloys in deaerated 0.1 mol/L H2SO4(aq), using a scanning droplet cell.

cond-mat.mtrl-sci↗

arXiv2023

An experimental high-throughput to high-fidelity study towards discovering Al-Cr containing corrosion-resistant compositionally complex alloys

Compositionally complex alloys hold the promise of simultaneously attaining superior combinations of properties, such as corrosion resistance, light-weighting, and strength. Achieving this goal is a challenge due in part to a large number of possible compositions and structures in the vast alloy design space. High-throughput methods offer a path forward, but a strong connection between the synthesis of an alloy of a given composition and structure with its properties has not been fully realized to date. Here, we present the rapid identification of corrosion-resistant alloys based on combinations of Al and Cr in a base Al-Co-Cr-Fe-Ni alloy. Previously unstudied alloy stoichiometries were identified using a combination of high-throughput experimental screening coupled with key metallurgical and electrochemical corrosion tests, identifying alloys with excellent passivation behavior. The alloy native oxide performance and its self-healing attributes were probed using rapid tests in deaerated 0.1 mol/L H2SO4. Importantly, a correlation was found between the electrochemical impedance modulus of the exposure-modified air-formed film and self-healing rate of the CCAs. Multi-element extended x-ray absorption fine structure analyses connected more ordered type chemical short-range order in the Ni-Al 1st nearest-neighbor shell to poorer corrosion resistance. This report underscores the utility of high throughput exploration of compositionally complex alloys for the identification and rapid screening of a vast stoichiometric space.

cond-mat.mtrl-sci↗