Effect of different oxidation modes on the growth of oxide layer of TC11 titanium alloy

Abstract

In order to study the effect of isothermal oxidation and cyclic oxidation on the oxide layer growth process of titanium alloys, high-temperature oxidization tests were conducted on TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si）titanium alloy in air at 650 °C. After 300 h of oxidization, the isothermal oxidation causes the formation of a dense oxide layer, contributing to increased resistance to further oxidization. During cyclic oxidization, the oxide layer exhibits a needle-like feature, containing large pores. The thickness of the oxide layers formed by cyclic oxidation and isothermal oxidation are approximately 8.6 μm and 2.7 μm, respectively. Under specific temperatures and oxidizing times, the isothermal oxidation process is controlled by the diffusion mechanism of oxygen, whereas the cyclic oxidation process is controlled by a combination of the interfacial reaction control and the diffusion mechanism of oxygen. This results in greater diffusion coefficients and faster growth kinetics for cyclic oxidation.