Snoek-type damping behavior of surface oxidation-treated Ti–Mo alloys

The Snoek relaxation damping behavior of surface oxidation-treated Ti–15 wt% Mo and Ti–40 wt% Mo alloys was investigated in this study. When compared to the untreated samples, both alloys exhibited higher damping capacities, higher peak temperatures, and broader peaks after the surface oxidation treatment. The broadening of peak was reflected by a lower activation energy obtained through fitting the peak than that obtained form frequency shift of the peak. The electron backscatter diffraction (EBSD) and hardness measurements were used to determine the composition of the dual phase zones and the hardness of each type of treated alloy, respectively. The oxygen distributions in both types of treated alloys were developed based on a diffusion model, and the thicknesses of the apparent oxygen solution zones (AOSZs) were determined to be 120 μm and 210 μm in the Ti–15 wt% Mo and Ti–40 wt% Mo alloys, respectively. The diffusion constants at a high oxidation temperature and at a low damping temperature were obtained for both alloys. The dependence of the damping capacity on the oxygen content in the Ti–40 wt% Mo alloys was much lower than that in the Ti–15 wt% Mo alloys. The contribution to the damping capacity from the AOSZ to the whole sample was estimated based on the law of mixtures. Estimating the contribution to the damping capacity from AOSZ is useful for future applications.