The characterisation and properties of chromised titanium alloys

Chromium enrichment of the surface of titanium alloys via fluid-bed reactor chemical vapour deposition (FBR-CVD) has been investigated. The coatings obtained on commercial purity (CP) titanium and a Ti6Al4V alloy were characterised using GDOES, BS-SEM, and XRD. It was revealed that the modified surface on both alloys consisted of a 5-20 μm thick porous deposition layer with >70 wt% chromium content and an inner 30-200μm thick low chromium-content diffusion zone. The surface hardness increased as a result of chromising and anodic polarisation testing revealed the general corrosion resistance is not compromised by chromium-enrichment. This surface treatment has the potential to improve the burn resistance of titanium alloys in aerospace application. © Institute of Materials Engineering Australasia Ltd.