Y.Z. Liu

TEM observation of oxide scale formed on a Ti–Al–Zr alloy oxidized at 360°C in alkaline steam

Ti–Al–Zr alloy has been oxidized at 360°C in alkaline steam at a pressure of 10.3 ± 0.7 MPa. Cross-sectional transmission electron microscopy (TEM) observations indicated that the oxide scale of Ti–Al–Zr alloy was composed of outer and inner subscales, in which the outer layer consists of anatase-TiO2 and the inner layer a mixture of TiO and Ti2O. The thickness of the Ti2O, TiO and anatase-TiO2 were approximately 50, 100 and 400 nm, respectively. These results were confirmed by X-ray energy dispersive spectrometry (EDS) measurements. The enhanced corrosion of titanium alloys in LiOH solution is attributed to a high hexagonal Ti2O to tetragonal TiO2 phase transformation rate induced by the substitution of Li+ for Ti4+ in the oxide layer.

Surface Characteristics and Corrosion Behavior of Ti-4Al-2V Alloy Implanted with Al and Nb

A Ti-Al-V alloy was implanted with Al and Nb to flounces ranging from 1 × 1017 to 1 × 1018 ions cm-2. Glancing Angle XRD measurement revealed α-Ti on Al-implanted samples and (α+β)-Ti on Nb-implanted samples. The (α+β)-phase samples exhibit better corrosion resistance. In the aerated solution with pH = 10, all the implanted surfaces are passive. Enhanced reoxidation was confirmed on implanted surfaces by Auger electron spectroscopy and X-ray photoelectron spectroscopy analysis. The corrosion in the solution with pH = 10 was governed predominantly by a TiO2 surface film.