IRRADIATION RESISTANCE ESTIMATION METHOD BY CRYSTAL LATTICE DISTORTIONS FAST CALCULATION FOR NI, CoCrFeNi AND CoCrFeMnNi FCC-ALLOYS

Abstract

Bulk materials, pure Ni, CoCrFeNi, and CoCrFeMnNi, were deposited by arc melting with subsequent cold-rolling till 85% thickness reduction and annealing at 1150°C. They were irradiated by 40 keV He2+ and 280 keV Kr14+ low-energy ions to the fluences of 2 × 1017 cm–2 and 5 × 1015 cm–2, respectively. Estimation of the distortions in the alloys was by calculating the normalized distortion parameter, which tends to increase with the increment of alloy complexity and atomic radii mismatch. x-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis showed a common superiority of CoCrFeNi over pure Ni in radiation resistance (less lattice deformation, no blistering). In both Ni and CoCrFeNi after ion irradiation, signs of tension microstress remained positive and the magnitudes showed similar responses, CoCrFeMnNi microstresses became compressive-negative; the dislocation density also showed decrease after Kr-irradiation compared with non-irradiation. Mn addition to the ternary alloy changed its behavior radically.Normalized distortion parameter calculation can be performed for quick simple comparative theoretical analysis comparison of the radiation resistance, but will not give full information about the difference between stoichiometries investigated.