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    Effects of heat treatment on the corrosion behavior and mechanical properties of aluminum alloy 2024
    (Elsevier, 2023) El Garchani, Fatima Ezzohra; Lgaz, Hassane; Kaya, Savas; Lee, Han-Seung; Ibrahim, Sobhy M.; Chafiq, Maryam; Ko, Young Gun
    Aluminum alloy, specifically 2024, is extensively utilized in the automotive and aerospace industries due to its light weight and superior mechanical properties. This study explores the corrosion behavior and mechanical characteristics of this alloy following quenching and aging heat treatments. Accelerated corrosion tests involved immersing samples in a salt spray chamber with a 5% NaCl solution, maintained at a temperature of 40 degrees C with a neutral pH. The alloy's microstructure and corrosion behavior were examined before and after the corrosion test, which included a heat treatment at 495 degrees C and aging for five days. Multiple tests, such as Vickers microhardness, optical microscopy, scanning electron microscopy (SEM), and tensile tests were performed. The surface characteristics, specifically the refined microstructure and residual stresses, were analyzed and their impact on localized corrosion was evaluated. The maximum strength value rose from 411 MPa to 512 MPa, and elongation increased correspondingly. Concerning corrosion sensitivity, a reduction was observed in the following order: AA2024-T3 (natural condition), AA2024-T3 (tempered condition), and AA2024-T3 (aged condition). The aged treatment appeared to enhance corrosion resistance, potentially due to the minimized size of corrosion products observed post-etching in various regions. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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    Unraveling Bonding Mechanisms and Electronic Structure of Pyridine Oximes on Fe(110) Surface: Deeper Insights from DFT, Molecular Dynamics and SCC-DFT Tight Binding Simulations
    (Mdpi, 2023) Lgaz, Hassane; Lee, Han-seung; Kaya, Savas; Salghi, Rachid; Ibrahim, Sobhy M.; Chafiq, Maryam; Bazzi, Lahcen
    The development of corrosion inhibitors with outstanding performance is a never-ending and complex process engaged in by researchers, engineers and practitioners. The computational assessment of organic corrosion inhibitors' performance is a crucial step towards the design of new task-specific materials. Herein, the electronic features, adsorption characteristics and bonding mechanisms of two pyridine oximes, namely 2-pyridylaldoxime (2POH) and 3-pyridylaldoxime (3POH), with the iron surface were investigated using molecular dynamics (MD), and self-consistent-charge density-functional tight-binding (SCC-DFTB) simulations. SCC-DFTB simulations revealed that the 3POH molecule can form covalent bonds with iron atoms in its neutral and protonated states, while the 2POH molecule can only bond with iron through its protonated form, resulting in interaction energies of -2.534, -2.007, -1.897, and -0.007 eV for 3POH, 3POH(+), 2POH(+), and 2POH, respectively. Projected density of states (PDOSs) analysis of pyridines-Fe(110) interactions indicated that pyridine molecules were chemically adsorbed on the iron surface. Quantum chemical calculations (QCCs) revealed that the energy gap and Hard and Soft Acids and Bases (HSAB) principles were efficient in predicting the bonding trend of the molecules investigated with an iron surface. 3POH had the lowest energy gap of 1.706 eV, followed by 3POH(+) (2.806 eV), 2POH(+) (3.121 eV), and 2POH (3.431 eV). In the presence of a simulated solution, MD simulation showed that the neutral and protonated forms of molecules exhibited a parallel adsorption mode on an iron surface. The excellent adsorption properties and corrosion inhibition performance of 3POH may be attributed to its low stability compared to 2POH molecules.