Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 4Citation - Scopus: 4Effect of Oxidation on Mechanical Properties of Copper Nanowire: a Reaxff (reactive Force Field) Molecular Dynamics Study(Aip Publishing, 2023) Aral, Gürcan; Islam, Md MahbubulNanostructures with high surface area to volume ratio, such as oxidized and coated Cu nanowires (NWs), exhibit unique mechanical properties due to their size and surface effects. Understanding the complex oxidation process of Cu NWs at nanoscale and quantifying its resulting effects on mechanical behavior and properties are significantly essential for effective usage of Cu NW devices in a wide range of applications in nanoelectronics. Here, we perform molecular dynamics simulations using ReaxFF (reactive force field) to investigate the oxidation process and mechanisms of [001]-oriented cylindrical Cu NWs and its contribution on the mechanical deformation behavior and material properties as a function of NW sizes. The relatively thin oxide CuxOy layer is formed on the surface of Cu NWs in an O-2 environment, creating a core/shell (Cu/CuxOy) NW structure that played a key role in governing the overall tensile mechanical deformation behavior and properties of Cu NW. The formation of oxide layer effects, including the resulting interface and defects, leads to a reduction in the initial dislocation nucleation barrier, which facilitates the onset of plasticity and stress relaxation, ultimately resulting in a negative impact on the tensile strength, Young's modulus, yield stress and strain, and flow stress when compared to pristine counterparts. It is worth noting that the tensile mechanical response and properties of the Cu NWs are highly dependent on the pre-existing oxide shell layer associated with the size of NW, determining the overall mechanical performance and properties of Cu NWs.Article Citation - WoS: 3Citation - Scopus: 3Atomic-Scale Investigation of the Effect of Surface Carbon Coatings on the Oxidation and Mechanical Properties of Iron Nanowires(Royal Society of Chemistry, 2021) Aral, Gürcan; Islam, Md MahbubulThe understanding of the complex atomistic-scale mechanisms of the oxidation process of carbon (C) coated iron nanowires (Fe NW) and also the resulting modulation of mechanical properties is a highly challenging task. We perform reactive molecular dynamics (RMD) simulations based on the ReaxFF force field to investigate the mechanisms of the oxidation process of [001]-oriented pristine cylindrical Fe NWs with and without a C coating in an O2 environment in order to obtain detailed insights into the influences of the surface C coating on the oxidation process at room temperature. Here, we show that the C-coated shell layer on the free surface of pristine Fe NWs partially controls the spontaneous oxidation when exposed to O2 molecules by hindering the absorption-dissociation of O2 molecules and diffusion of O ions into the shell layer. In particular, the surface modification of the pristine Fe NW with the C-coated shell layer has pronounced effects on the improvement of oxidation resistance by lowering the surface reactivity, which limits the formation of an oxide shell layer on the free surface of the NW. The formation of strong Fe-C bonds in the C-coated shell layer largely restrains the oxidation process. Furthermore, to examine the influence of the C-coated shell layer on the resulting modulation of mechanical properties of the pristine Fe NW, we systematically investigate the mechanical deformation processes and related properties of Fe NW with and without a C coating including their oxidized counterparts subjected to both uniaxial tensile and compressive loads at room temperature. The yield stress and strain (the elastic limit) of Fe NWs including the elastic and plastic deformation phase of the stress-strain relationship are found to be sensitive to the loading modes, the existence of the C-coated shell layer and the resulting formation of an oxide shell layer on the surface of the C-coated Fe NW.Article Citation - WoS: 8Citation - Scopus: 8Atomistic Insights on the Influence of Pre-Oxide Shell Layer and Size on the Compressive Mechanical Properties of Nickel Nanowires(American Institute of Physics, 2019) Aral, Gürcan; Islam, Md Mahbubul; Wang, Yun-Jiang; Ogata, Shigenobu; van Duin, Adri C. T.We used ReaxFF reactive molecular dynamics simulations to systematically investigate the effects of a pre-oxide shell layer on the mechanical properties of [001]-oriented nickel (Ni) nanowires (NWs) under the uniaxial compressive loading at room temperature. The pristine Ni NWs are considered as references to compare the mechanical properties of the oxide-coated NWs. We found that the mechanical properties of pristine Ni NWs under uniaxial compression are sensitive to both the diameter of the NWs and the pre-oxide shell layer, and their combined effect determines the overall stress and strain behaviors. The compressive strength of the pristine NWs decreases significantly with the decreasing diameter. We observe that the native defected amorphous pre-oxide shell layer with similar to 1.0 nm thickness leads to a lowering of the mechanical compressive resistivity of NWs and causes additional softening. Oxide-coated NWs exhibit a lesser size-dependent unique properties and a lower overall yield strength compared to their pristine counterparts. The reduction of the mechanical compressive yield stress and strain with the decreasing diameter is due to the substantial changes in plastic flow as well as correlated with the existence of the pre-oxide shell layer as compared to its pristine counterpart. Particularly, pre-oxide shell layers have pronounced effects on the initiation of initial dislocations to onset plastic deformation and consequently on the overall plastic response. Published under license by AIP Publishing.