First-principles study of helium behaviors in oxide dispersion strengthened nickel alloys

Abstract

• YAlO 3 (YAH) shows comparable elastic constants with Ni, suggesting potential deformation compatibility of the YAH strengthened Ni-based ODS alloys. • YAH can impede the He segregation towards Ni grain boundry by capturing the He atoms at the Ni/oxide interface with lower formation energy. • Once the interfacial traps are saturated, He atoms prefer to diffuse into the YAH bulk and separate individually in the octahedral sites. • For YAH trapped helium atoms, strong hybridization between the He-1s and surrounding O-2p orbitals can induce enhanced mechanical binding. Y-Al-O oxides are characterized to be primary nanoprecipitates in oxide dispersion strengthened (ODS) Ni-based alloys for Very High Temperature Reactor (VHTR). We reported a first-principles study to assess the mechanical properties and helium behaviors in YAlO 3 (YAH) strengthened Ni-based ODS alloys from the nickel grain boundary and YAlO 3 bulk to the Ni/ YAlO 3 interface. The results suggest that YAH shows a elastic manner and well deformation compatibility with the matrix. The oxide strengthened system is expected to inhibit the formation of helium bubbles by captuering helium atoms dispersedly in YAlO 3 bulk and Ni/ YAlO 3 interface and thus hinder the He induced embrittlement.These findings provide basic understandings of the helium behaviors in a Al-cotnaining Ni-based ODS alloy.