Focused ion beam–SIMS oxygen assay of the surface of titanium alloys prepared by the shot peening process

Authors


Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.

E-mail: meurig.thomas@sheffield.ac.uk

Abstract

Shot peening introduces subsurface residual compressive stresses in titanium alloys to depths of up to 500 µm. Although the microhardness method is established as a method for determining interstitial oxygen concentration gradients of such alloys, the near surface plastic deformation arising from shot peening is a source of measurement unreliability. An alternative method based on negative ion, focused ion beam–SIMS has been trialed for a shot peened Ti-834 alloy thermally exposed for times and temperatures comparable with service conditions in the ‘hot-end’ compressor stages of a modern gas-turbine aero-engine. Focused ion beam–SIMS measurements successfully measured enhanced oxygen ingress into the topmost 100 µm of the shot-peened Ti-834 after prolonged thermal exposure. Copyright © 2012 John Wiley & Sons, Ltd.

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