title: Anomalous Stress Response of Ultrahard WB_{n} Compounds.
abstract: Boron-rich tungsten borides are premier prototypes of a new class of ultrahard compounds. Here, we show by first-principles calculations that their stress-strain relations display surprisingly diverse and anomalous behavior under a variety of loading conditions. Most remarkable is the dramatically changing bonding configurations and deformation modes with rising boron concentration in WB_{n} (n=2, 3, 4), resulting in significantly different stress responses and unexpected indentation strength variations. This novel phenomenon stems from the peculiar structural arrangements in tungsten borides driven by boron's ability to form unusually versatile bonding states. Our results elucidate the intriguing deformation mechanisms that define a distinct type of ultrahard material. These new insights underscore the need to explore unconventional structure-property relations in a broad range of transition-metal light-element compounds.
authors.affiliation: College of Materials Science and Engineering and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.|Department of Physics and High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154, USA.
authors.forename: Quan
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Physics and High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154, USA.|Laboratory of Clean Energy Technology, Changchun University of Science and Technology, Changchun 130022, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhou
authors.affiliation: College of Materials Science and Engineering and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
authors.forename: Weitao
authors.initials: W
authors.lastname: Zheng
authors.affiliation: College of Materials Science and Engineering and State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Physics and High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154, USA.
authors.forename: Changfeng
authors.initials: C
authors.lastname: Chen