Interstitial-Boron Solution Strengthened WB${}_{3+x}$

Abstract

By means of variable-composition evolutionary algorithm coupled with density functional theory and in combination with aberration-corrected high-resolution transmission electron microscopy experiments, we have studied and characterized the composition, structure and hardness properties of WB${}_{3+x}$ ($x$ $<$ 0.5). We provide robust evidence for the occurrence of stoichiometric WB${}_3$ and non-stoichiometric WB${}_{3+x}$ both crystallizing in the metastable $hP$16 ($P{6}_3/mmc$) structure. No signs for the formation of the highly debated WB${}_4$ (both $hP$20 and $hP$10) phases were found. Our results rationalize the seemingly contradictory high-pressure experimental findings and suggest that the interstitial boron atom is located in the tungsten layer and vertically interconnect with four boron atoms, thus forming a typical three-center boron net with the upper and lower boron layers in a three-dimensional covalent network, which thereby strengthen the hardness.

5 pages, 5 figures

References in corpus (3)

• Intrinsic Correlation between Hardness and Elasticity in Polycrystalline Materials and Bulk Metallic Glasses
• Discovery of a superhard iron tetraboride superconductor
• New Superconducting and Semiconducting Fe-B Compounds Predicted with an Ab Initio Evolutionary Search

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