Exploration of stable stoichiometries, ground-state structures, and mechanical properties of the W–Si system. Issue 10 (July 2020)

• Record Type: Journal Article
• Authors: Yan, Haiyan; Wei, Zhiting; Zhang, Meiguang; Wei, Qun
• Is Part Of: Ceramics international. Volume 46:Issue 10(2020)Part B
• Page Start: 17034
• Page End: 17043
• Publication Date: 2020-07
• Subjects: Tungsten silicides -- First-principles -- Electronic structure -- Mechanical strength; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.03.290
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Refractory tungsten silicides have been identified as typical high-temperature structural materials with excellent mechanical and thermal properties in various industrial applications. Here, we show the first extensive crystal structures search of W–Si system over a wide range of stoichiometries at ambient condition, using first-principles swarm intelligence structure search methods. Besides the well-known W5 Si3 and WSi2, three novel and unexpected stoichiometries of W2 Si, WSi, and W3 Si4 with tetragonal ground-state structures were firstly uncovered and suggested to be experimentally synthesizable according to the convex hull calculations. It is found that the high silicon content benefits the formation of the puckered double W–Si zigzag covalent chains in W m Si n, resulting in the enhanced resistance to shear deformation related to the macroscopic hardness. Results on the ideal tensile and shear strengths calculations indicated that the failure modes in the studied W m Si n are mainly dominated by the shear type along the (110) [ 1 1 ‾ 0 ] directions. Further analysis of atomic shear deformation demonstrates that the collapse of Si–W building blocks is responsible for the lattice stability and achievable mechanical strength of W m Si n .