Phase transformation strengthening of high-temperature superalloys

T. M. Smith, B. D. Esser, N. Antolin, A. Carlsson, R. E. A. Williams, A. Wessman, T. Hanlon, H. L. Fraser, W. Windl, D. W. McComb, M. J. Mills

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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 CO2 emissions. 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.

Original languageEnglish
Article number13434
Number of pages7
JournalNature Communications
Volume7
DOIs
Publication statusPublished - 22 Nov 2016
Externally publishedYes

Cite this

Smith, T. M., Esser, B. D., Antolin, N., Carlsson, A., Williams, R. E. A., Wessman, A., Hanlon, T., Fraser, H. L., Windl, W., McComb, D. W., & Mills, M. J. (2016). Phase transformation strengthening of high-temperature superalloys. Nature Communications, 7, [13434]. https://doi.org/10.1038/ncomms13434