Evaluation of Tribological and Fatigue Properties of a Near-β Titanium Alloy for Aerospace Applications

The aim of this investigation is to study the tribological and fatigue properties of Ti–10V–2Fe–3Al, a near-β titanium alloy for aerospace components subjected to cyclic loading and wear e.g. flap tracks. Uniaxial tensile and rotation bending tests were employed to study the mechanical response of the alloy to static and cyclic loads, and its wear resistance was assessed using a ball-on-disk configuration against AISI 52100 steel counterface at 0.8N–5N normal loads and 0.01m/min sliding speed for 5000 cycles (200m). The tests were also conducted on Ti–6Al–4V (α+β alloy, mill-annealed microstructure), the most widely used titanium alloy, under the same conditions for the purpose of comparison. It was found that Ti–10V–2Fe–3Al exhibited a 27% higher ductility and a 12% higher fatigue endurance limit compared with Ti–6Al–4V. Fractographic observations using a scanning electron microscope (SEM) revealed ductile type of failure in both alloys; however, fatigue cracks followed a tortuous path of propagation in Ti–10V–2Fe–3Al. In terms of tribological properties, Ti–10V–2Fe–3Al experienced lower wear rates. The SEM observations coupled with energy dispersive x-ray spectrometry (EDS) of wear tracks, counterface wear scars and wear debris particles indicated ploughing, delamination and oxidation at low loads (<5N) as well as material transfer from the counterface at high loads (5N). Cross-sectional observation of wear tracks using focused ion beam (FIB) milling technique revealed the formation of a mechanically mixed layer (MML) on the worn surfaces that was denser, thinner and well-bonded at the interface in Ti–10V–2Fe–3Al.