Characterisation of surface recrystallisation in a grit-blasted single-crystal superalloy

ABSTRACT

In this work, detailed experimental insights regarding the microstructural features on surface recrystallisation of a grit-blasted single crystal superalloy DD6 have been obtained by transmission electron microcopy (TEM), scanning transmission electron microcopy (STEM), scanning electron microscopy and electron backscattered diffraction (EBSD) techniques. The broadened diffraction ring arcs typical for micro-textures revealed the fragmented finer grains after surface grit-blasting. Energy dispersive spectroscopy analysis and STEM mapping confirmed the characteristic elements for differentiation of γ′ and γ phase, and the precipitated secondary or tertiary γ′ in the recrystallised region was characterised by dark field TEM. Moreover, the recrystallisation depth was feasibly revealed by ion-etching and further used for EBSD imaging without polishing. The resulted EBSD pole figures and misorientation profiles confirmed that the recrystallised region exhibited a rather random orientation, destroying the original single crystal type.

KEYWORDS:

• Single crystal superalloy
• grit-blast
• surface recrystallisation
• TEM
• EBSD

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Science and Technology Project of Shaanxi Province under [grant number 2016JQ5025]; Key Laboratory Foundation of Shaanxi Provincial Department of Education under [grant number 16JS064]; the National Natural Science Foundation of China under [grant number 51604223]; and Strong Industrial Base Project under [grant number TC160A310-18].