Irradiation Damage Evolution Dependence on Misorientation Angle for Σ 5 Grain Boundary of Nb: An Atomistic Simulation-Based Study

Abstract Niobium as refractory element holds ability to arrest the primary radiation damage in reactor's fissionable conditions and can withstand high-temperature applications. We have inclined the investigation of irradiated Nb Σ 5 symmetric-tilt angled grain boundary (STGB) models at two high-angled grain boundary misorientation: 53.13 deg (Σ 5(2–10)/(120)) and 36.87 deg (Σ 5(3–10)/(130)), respectively. A hybrid of Ziegler–Biersack–Littmark (ZBL) and embedded atom method (EAM) potentials were superimposed to simulate radiation damage. Statistical averaging of the displacement cascades was conducted to study the dynamic evolution of the point defects and interstitial clusters at varying magnitudes of primary knock-on atom (PKA) energies, irradiation temperatures, and PKA directions. The irradiated grain bounary (GB) models were compared with an irradiated bulk Nb specimen, and the results of the study indicate that the irradiated Nb system with greater misorientation angle, i.e., Nb Σ 5 (ɵ = 53.13 deg) survived with lower number Frenkel pair defects as well as the population small-sized interstitial clusters. The point defect cluster analysis indicated the highest population of interstitial clusters survived in Nb STGB models were irradiated along <1 3 5> PKA direction and 100 keV recoil energies respectively.