title: Atomic scale modelling of hexagonal structured metallic fission product alloys.
abstract: Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)-making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance.
authors.affiliation: Institute of Materials Engineering , Australian Nuclear Science and Technology Organisation, Locked Bag 2001 , Kirrawee DC, New South Wales 2232, Australia.
authors.forename: S C
authors.initials: SC
authors.lastname: Middleburgh
authors.affiliation: Institute of Materials Engineering , Australian Nuclear Science and Technology Organisation, Locked Bag 2001 , Kirrawee DC, New South Wales 2232, Australia ; Department of Nanomaterials , University of Technology , Sydney, New South Wales, Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: King
authors.affiliation: Institute of Materials Engineering , Australian Nuclear Science and Technology Organisation, Locked Bag 2001 , Kirrawee DC, New South Wales 2232, Australia.
authors.forename: G R
authors.initials: GR
authors.lastname: Lumpkin
keywords: density functional theory; fission product; high-entropy alloy; nuclear fuel performance and safety