Role of chlorine in the oxidation resistance of Ti-45at.% Al-1.6at.%Mn intermetallic compound

In order to investigate the role of chlorine in the oxidation resistance of Ti-45at.%Al-1.6at.%Mn intermetallic compounds, specimens with and without chlorine were prepared by a reactive sintering and a remelting process, respectively, and then isothermally oxidized at temperatures of 800 to 1000°C. The oxidation resistance of reactive-sintered Ti-45at.%Al-1.6at.%Mn containing 0.02 wt.%Cl was superior to that of remelted specimens due to the formation of a protective Al2O3, layer. From the results of an EPMA line scan of a cross-section of the oxide layer, carbon and chlorine peaks were detected on the TiO2 layer of the reactive-sintered specimens suggesting that TiO2 can decompose to TiCl4 through the reaction with Cl2 and C (or CO). As a result of the chlorination of TiO2, the growth of TiO2 could be constrained and a protective A12O3 scale was easily formed on the reactive-sintered alloy.