Influence of Surface Segregation on the Mechanical Property of Metallic Alloy Nanowires
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ace Segregation on the Mechanical Property of Metallic Alloy Nanowires Aditi Datta, Zhiyao Duan and Guofeng Wang MRS Proceedings / Volume 1424 / 2012 DOI: 10.1557/opl.2012.679
Link to this article: http://journals.cambridge.org/abstract_S1946427412006793 How to cite this article: Aditi Datta, Zhiyao Duan and Guofeng Wang (2012). Influence of Surface Segregation on the Mechanical Property of Metallic Alloy Nanowires. MRS Proceedings,1424, mrsf111424ss1537 doi:10.1557/opl.2012.679 Request Permissions : Click here
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Mater. Res. Soc. Symp. Proc. Vol. 1424 © 2012 Materials Research Society DOI: 10.1557/opl.2012.679
Influence of Surface Segregation on the Mechanical Property of Metallic Alloy Nanowires Aditi Datta, Zhiyao Duan, and Guofeng Wang a) Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 ABSTRACT The influence of surface segregation on the elastic properties of Pt-M (M = Ni, Co, or Fe) nanowires (NWs) are examined by comparing the predicted Young’s moduli of the segregated and non-segregated nanowires using density functional theory (DFT) calculations and the computed stress-strain curves under tensile loading using molecular dynamics (MD) simulation method. The moduli of the segregated NWs were found to be higher than that of the nonsegregated ones. It is believed that the surface segregation increases the number of Pt-M bonds across the outermost and second surface layers, and thus enhances the Young’s modulus of the segregated Pt-M nanowires. MD results confirm our DFT results and it is found that onset of plastic deformation could be altered by the surface segregation process, as well. INTRODUCTION Surface segregation is an intriguing phenomenon widely observable at the extended surfaces of metallic alloys and refers to the disparity of chemical composition at the surface from the composition in the bulk [1]. Surface segregation process was also predicted to occur in the nanostructured materials [2] and could be employed to enhance the catalytic properties of the materials [3]. In case of (111) and (100) surfaces of disordered Pt-Ni alloys, a sandwich surface structure, in which Pt strongly enriches the outermost and third surface layers while the Ni atoms are segregated to the second surface layer, is observed after annealing [4, 5]. Consequently, it is anticipated that surface segregation could change the surface energy and/or surfaces stress and hence modulate the mechanical deformation process of the Pt-Ni nanomaterials. Alloy nanowires are an important class of functional materials and the mechanical properties and the characteristics of elastic deformation process in the nanowires could be strongly affected by the surface properties [6, 7]. From molecular dynamics (MD) simulations with empirical potentials, it has been observed that the Young’s modulus of metallic nanowires depends strongly on the size [8, 9, 10], shape [11], orientation [9, 12, 13],
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