Effect of Al2O3 layer on improving high-temperature oxidation resistance of siliconized TiAl-based alloy

Abstract TiAl-based specimens were siliconized with two different kinds of cementation respectively, one is 23 vol.% Si + 77 vol.% Al 2 O 3 , and the other is 23 vol.% Si + 77 vol.% ZrO 2 . SEM observation showed that a Ti 5 Si 3 -based layer, in which some Al 2 O 3 particles dispersed, formed on the surface after siliconization. Further observation showed that an extra outer Al 2 O 3 layer existed on the surface of specimens siliconized with 23 vol.% Si + 77 vol.% Al 2 O 3 , while no such Al 2 O 3 layer was found in specimens siliconized with 23 vol.% Si + 77 vol.% ZrO 2 . The cyclic oxidation test performed at 900 °C shows that the oxidation resistance was significantly improved by siliconizing. By comparison, the specimens that siliconized with 23 vol.% Si + 77 vol.% Al 2 O 3 exhibits a better oxidation resistance than that with 23 vol.% Si + 77 vol.% ZrO 2 . It was deduced that the extra outer Al 2 O 3 layer is beneficial to the oxidation resistance of siliconized TiAl-based alloy.