Oxidation behavior of TiAl alloy treated by plasma surface chromizing process

TiAl–Cr alloy was prepared on surface of TiAl alloy by plasma chromizing process. The oxidation kinetics of the TiAl–Cr surface alloy and the bulk TiAl were examined. The morphology and constituent of the oxide scales were observed. The results indicated that the oxidation resistance of TiAl was improved significantly after the alloying treatment. The scale of TiAl–Cr surface alloy was mainly consisted of Cr2O3 initially, then combination of Cr2O3, Al2O3 and TiO2, and eventually the mixture of Al2O3 and TiO2. The oxide scale was dense and integrated throughout the oxidation process. The improvement is owing to the enhancing of scale adhesion and the preferential oxidation of aluminum brought by the alloying effects of chromium.

► Chromium as alloying elements was added in to TiAl at the surface.
► TiAl–Cr presented improved oxidation resistance.
► Oxide scale of bare TiAl delaminated and peeled off at early stage of the oxidation.
► Oxide scale of TiAl–Cr was integrated and compact throughout the oxidation process.