Quantifying the effect of oxygen on micro-mechanical properties of a near-alpha titanium alloy

TL;DR

This study investigates how oxygen affects the micro-mechanical properties of a near-alpha titanium alloy, using advanced microscopy and nanoindentation to relate oxygen ingress to hardness and microstructure changes.

Contribution

It provides detailed nanoscale insights into oxygen ingress mechanisms and their impact on mechanical properties in titanium alloys, combining multiple analytical techniques.

Findings

Oxygen ingress correlates with increased hardness.

Microstructure influences oxygen penetration pathways.

APT reveals oxygen accumulation at alpha/beta interfaces.

Abstract

Atom probe tomography (APT), electron probe microanalysis (EPMA) and nanoindentation were used to characterise the oxygen-rich layer on an in-service jet engine compressor disc, manufactured from the titanium alloy TIMETAL 834. Oxygen ingress was quantified and related to changes in mechanical properties through nanoindentation studies. The relationship between oxygen concentration, microstructure, crystal orientation and hardness has been explored through correlative hardness mapping, EPMA and electron backscatter diffraction (EBSD). The role of microstructure on oxygen ingress has been studied and oxygen ingress along a potential alpha/ beta interface was directly observed on the nanoscale using APT.