Characterizing the radiation-induced defect behavior in Inconel 617 through molecular dynamics simulations

Abstract

Inconel 617, a nickel–chromium–cobalt–molybdenum superalloy, is a promising candidate for high-temperature nuclear applications due to its mechanical strength and oxidation resistance. Understanding its radiation response is crucial for evaluating its long-term performance. In this study, we employed molecular dynamics (MD) simulations with a modified embedded atom method (MEAM) potential to investigate defect formation and evolution in Inconel 617 with the composition Ni₅₂Cr_23.5Co_11.4Mo_9.7Fe_1.6Al_1.8, under single-cascade and successive overlapping cascade simulations up to 0.2 displacements per atom (dpa). Successive cascade simulations revealed that Inconel 617 exhibits a defect concentration comparable to values reported in the literature for equimolar NiCrCo. However, it forms fewer dislocations and smaller defect clusters, suggesting improved radiation resistance up to 0.2 dpa. To isolate the role of molybdenum (Mo), we also examined a comparable alloy (Ni_59.8Cr_27.1Co_13.1) without Mo. Our results show that, while Mo does not significantly affect the number of Frenkel pairs (FPs) produced in single 5 keV cascades, it suppresses the formation of large interstitial clusters during successive cascade overlap simulations, thereby enhancing radiation resistance. Tensile simulations indicate that irradiation-induced dislocations reduce both the yield strength and Young’s modulus. These findings provide insights into the radiation tolerance of Inconel 617 and highlight the critical role of Mo in defect dynamics.