Theoretical tensile stress in tungsten single crystals by full-potential first-principles calculations

Fully self-consistent ab initio electronic structure calculation of theoretical tensile strength is performed for the first time using full-potential LAPW method. As a specific example, tensile strength of single-crystalline tungsten loaded uniaxially along the (001) and (111) directions is analyzed. Although tungsten is elastically nearly isotropic (C44 ≈ C′), theoretical tensile strength exhibits a marked anisotropy (σ001th = 0.289 Mbar, σ111th = 0.401 Mbar). This anisotropy is explained in terms of structural energy differences between bcc, fcc and simple cubic structures which occur on the calculated deformation paths. Theoretical results compare favorably with experimental value of 0.247 ± 0.036 Mbar obtained for tungsten whiskers grown along the (110) direction.