Enhancing the irradiation resistance of L12 intermetallics by incorporating multiple principal elements through computational modeling

Abstract

Ordered L12 γ′ Ni3Al intermetallics are essential strengthening components to maintain the high strength of Ni-based superalloys and recently developed high entropy alloys at elevated temperatures. Under service conditions, structural disorder is usually encountered in these intermetallics, resulting in significant loss of their strengthening functionality. Thus, retaining the degree of order of the L12 intermetallics is vital for their long-term reliability and serviceability. In this study, atomistic simulations and rate equation analysis are employed to highlight a notable enhancement in the reordering ability of L12 intermetallics by incorporating multiple principal elements. Specifically, we examine the effects of Co and Ti addition on the irradiation-induced disordering and kinetic reordering process of L12 intermetallics. Our results reveal that the incorporation of Ti in the Al sublattice can maintain comparable disordering resistance as Ni3Al. Better yet, the introduction of Ti or Co fosters vacancy migration, which accelerates the kinetic reordering rate during the defect diffusion stage. A synergistic effect of Ti and Co in promoting kinetic reordering is also observed. Our work thus suggests a promising approach for designing irradiation-resistant multicomponent intermetallics, which can retain a high degree of structural order under irradiation with chemical disorder contributed by desirable compositions.

Keywords

• L12 intermetallics
• Chemical disorder
• Structural order under irradiation
• Kinetic reordering by vacancy diffusion
• Molecular dynamics