The structure and energy of symmetric tilt grain boundaries in tungsten

Considering the limitations of experiments and the necessity for improving the radiation resistance of materials based on the grain boundary (GB) engineering, more complete results on underlying GB properties are not yet available, and the correlations between such properties remain to be figured out. Here, we constructed a sys-tematical database of the basic properties of 113 distinct symmetric tilt grain boundaries (STGBs) with (100), (110), and (111) axes in tungsten, including the GB energy, work of separation, excess volume and a single vacancy/interstitial segregation energy, calculated by molecular statics simulations with six interatomic po-tentials. Then, the correlations between these parameters were systematically investigated. We found that although the magnitude of GB properties yielded by these potentials is different, the correlations between these parameters are consistent with each other. According to the analysis of dislocations in these STGB's stable structures, we divided these STGBs into two categories, namely GBs consisting of discrete and overlapping dislocations (DDGBs vs. ODGBs), and identified the dislocation type, i.e., (100), (110), and 1/2(111) disloca-tions, and threshold angles. For DDGBs, the work of separation and excess volume are negatively and positively proportional to the GB energy, respectively, while the minimal vacancy/interstitial segregation energy is close to a constant value for the STGBs consisting of the same dislocations. For ODGBs, there is no obvious correlation between these parameters. In addition, we found that the main contribution to the excess volume is within 5 angstrom around the GB, and the minimal vacancy/interstitial segregation energy of (110) STGBs is lower than (100) and (111) STGBs, showing a greater capture ability for vacancies/interstitials. We also confirmed that, in Fe and W, STGBs with the same crystallography have strongly correlated energies, which can be scaled by the cohesive energy or different shear moduli, depending on the chosen potential.