Anti-Oxidation Property and Reaction Diffusion Process of Pre-Sulfidized TiAl Alloy

摘要

The oxidation resistance and degradation processwere investigated in air at 1173K for up to 1.44 Ms for the TiAlalloy, which has been pre-sulfidized at 1173K in a H2-H2S gasmixture to form a TiAl3(+TiAl2) layer with 20 micron thickness onthe alloy surface. And the reaction diffusion process of the TiAl3-TiAl2-TiAl system was computer-simulated.The TiAl3 layer with very good oxidation resitance changedquickly into a TiAl2 at 80 ks, which agreed well with the calculatedone. The TiAl2 layer transformed slowly to a TiAl, indicating goodoxidation resistance for up to 810 ks, while with further oxidationit degraded significantly at 1.44 Ms, in contrast to the calculatedtime of 4 Ms. This is due to a localized oxidation along alloy grainboundaries, and the degradation mechanism was proposed.