Interfacial reactions and oxidation behavior of A1_2O_3 and A1_2O_3/Al coatings on an orthorhombic Ti2AlNb alloy

摘要

The uniform and dense A1_2O_3 and A1_2O_3A1 coatings were deposited on an orthorhombic Ti2AlNb alloy by filtered arc ion plating. The interfacial reactions of the A1_2O_3/Ti_2AlNb and A1_2O_3/Al/Ti_2AlNb specimens after vacuum annealing at 750℃ were studied. In the A1_2O_3/Ti_2AlNb specimens, the A1_2O_3 coating decomposed significantly due to reaction between the A1_2O_3 coating and the O-Ti_2AlNb substrate. In the A1_2O_3/Al/Ti_2AlNb specimens, α γ-TiAl layer and an Nb-rich zone came into being by interdiffusion between the Al layer and the O-Ti_2AlNb substrate. The -y-TiAl layer is chemically compatible with A1_2O_3, with no decomposition of A1_2O_3 being detected. No internal oxidation or oxygen and nitrogen dissolution zone was observed in the O-Ti_2AlNb alloy. The A1_2O_3/Al/Ti_2AlNb specimens exhibited excellent oxidation resistance at 750℃.