title: Phase transformation strengthening of high-temperature superalloys.
abstract: Decades of research has been focused on improving the high-temperature properties of nickel-based superalloys, an essential class of materials used in the hot section of jet turbine engines, allowing increased engine efficiency and reduced CO2emissions. Here we introduce a new 'phase-transformation strengthening' mechanism that resists high-temperature creep deformation in nickel-based superalloys, where specific alloying elements inhibit the deleterious deformation mode of nanotwinning at temperatures above 700 °C. Ultra-high-resolution structure and composition analysis via scanning transmission electron microscopy, combined with density functional theory calculations, reveals that a superalloy with higher concentrations of the elements titanium, tantalum and niobium encourage a shear-induced solid-state transformation from the γ' to η phase along stacking faults in γ' precipitates, which would normally be the precursors of deformation twins. This nanoscale η phase creates a low-energy structure that inhibits thickening of stacking faults into twins, leading to significant improvement in creep properties.
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Smith
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Esser
authors.affiliation: Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: N
authors.initials: N
authors.lastname: Antolin
authors.affiliation: FEI Company, Achtserweg Noord 5, Eindhoven 5651, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Carlsson
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: R E A
authors.initials: RE
authors.lastname: Williams
authors.affiliation: G.E. Aviation, Cincinnati, Ohio 45215, USA.
authors.forename: A
authors.initials: A
authors.lastname: Wessman
authors.affiliation: G.E. Global Research Center, Niskayuna, New York 12309, USA.
authors.forename: T
authors.initials: T
authors.lastname: Hanlon
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Fraser
authors.affiliation: Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: W
authors.initials: W
authors.lastname: Windl
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: McComb
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Mills