Effect of He on the structure and bonding properties of W: A first-principles computational tensile test

Using a first-principles computational tensile test (FPCTT), we have investigated the effect of helium (He) on the structure and bonding properties of tungsten (W), which is a promising plasma-facing material in nuclear fusion Tokamak. Density of states results reveal the underlying reason that the substitutional site for He is the most energetically favorable, while the tetrahedral interstitial site is more favorable than the octahedral interstitial one. The FPCTT shows that the ideal tensile strength is 29.1 GPa at the strain of 14% along the [0 0 1] direction for intrinsic W, while it decreases to 28.2 GPa at the same strain when one impurity He atom is introduced. A local bond-breaking region around He forms in the tensile process due to the presence of He, which suggests He will have a large effect on the bonding properties of W.