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Title:Strain around VNx dislocation core
Author(s):Mei, Antonio
Subject(s):Material Science
Abstract:Vanadium nitride, a Group-VB transition-metal nitride, has a long history of milestones as a material exhibiting extraordinary mechanical properties. Pioneering work on TiN/VN(001) superlattices demonstrated the first man-made superhard composites with hardness values exceeding values of individual TiN and VN components. Recent investigations reveal that VN exhibits reduced abrasion versus traditional hard coatings, including TiN, due to the formation of a naturally lubricious surface. Despite high hardness and low-friction surfaces, state-of-the-art VN coatings currently suffer when exposed to high stress conditions due to their brittleness. To enhance the toughness of VN coatings, first-principle calculations were employed to systematically screen for dopants and atomic configurations that would yield more compliant responses to stresses and allow for higher hardness values. Using the theoretical findings as guidance for experiments, we discover that understoichiometric VNx films display 20% higher hardness values and enhanced toughness compared to their stoichiometric counterparts. The image shows (a) a high-resolution transmission electron micrograph of a dislocation core in VNx. The core is highlighted in (b) and (c), which are Fourier-filtered and phase images of (a). Inserts (d)-(f) show εyy, εxx, and εxy strain fields, obtained from a geometrical phase analysis of (a), around the VNx dislocation core.
Issue Date:2015
Rights Information:Copyright 2015 Antonio Mei
Date Available in IDEALS:2015-04-23

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