Atomistic modeling of radiation-induced disordering and dissolution at a Ni/Ni3Al interface. Issue 9 (20th January 2015) - Lee, Tongsik
Abstract: Abstract : L12 -ordered γ′ precipitates embedded in a fcc γ matrix impart excellent mechanical properties to nickel-base superalloys. However, these enhanced mechanical properties are lost under irradiation, which causes the γ′ precipitates to disorder and dissolve. We conduct an atomic-level study of radiation-induced disordering and dissolution at a coherent (100) facet of an initially ordered γ′ Ni3 Al precipitate neighboring a pure Ni γ matrix. Using molecular dynamics, we simulate collision-induced events by sequentially introducing 10 keV primary knock-on atoms with random positions and directions. In the absence of thermally assisted recovery processes, the ordered Ni3 Al layer disorders rapidly within 0.1–0.2 dpa and then gradually dissolves into the adjacent Ni layer at higher doses. Both the disordering efficiency and mixing parameter calculated from the simulations lie within the range of values found by experiments carried out at room temperature, where thermally activated diffusion is insignificant.