Comparison of high temperature oxidation resistance of two different gradesof Gamma-TiAl advanced material

In the present research work, the high temperature oxidation resistance of two grades of -TiAl advancedalloy including Ti-48Al-2Nb-2Cr (at. %) and Ti-45Al-2Nb-2Mn-1B (at. %) was compared via isothermaloxidation test at 1123K for 200 hours. The isothermal oxidation test results indicate that industrial gradeof Ti-48Al-2Nb-2Cr (at. %) possesses a better oxidation resistance and more desirable oxide scalesadherence compared to Ti-45Al-2Nb-2Mn-1B (at. %) alloy. The detailed microstructural and phaseidentifications of the formed oxide scales on two different grades of -TiAl alloy were performed usingSEM and XRD techniques. According to the obtained results in this work, it is observed that the structureof oxide scales that formed on both types of -TiAl alloys contains two separate layers including an outerTiO2 layer and an inner layer of mixed TiO2+Al2O3. Additionally, it is observed that there is an Aldepletedzone under the inner layer which may be created due to the outward diffusion of Al from thesubstrate to the outer oxide scales. Also, it was observed that there is no void in the oxide scale formed onTi-48Al-2Nb-2Cr (at. %) alloy, while in Ti-45Al-2Nb-2Mn-1B (at. %) counterpart, several voids areobserved in the associated oxide scales. It seems that the relatively better oxidation resistance of Ti-48Al-2Nb-2Cr (at. %) industrial grade is owing to presence of Cr in this alloy.

Comparison of high temperature oxidation resistance of two different gradesof Gamma-TiAl advanced material Keywords:

-TiAl alloy , Isothermal oxidation , Oxide scales , Microstructure.