Hot-dip Aluminizing Fabrication of TiAl_3 Coating on TA15 Alloy and Its High Temperature Oxidation Behaviors

摘要

A TiAl_3-rich coating was developed by hot-dip aluminizing method and subsequent interdiffusion treatment on Ti-6.5Al-1Mo-1V-2Zr (mass %) alloy for high temperature resistance. Interrupted oxidation at temperatures from 973 to 1173 K and isothermal oxidation at temperatures from 923 to 1073 K of the TiAl_3-rich coating were conducted. The coating markedly decreased the oxidation rate in comparison with the substrate alloy at 1073 K and lower during the interrupted oxidation, and a layered structure of Al_2O_3/TiAl_3/TiAl2/TiAl/alloy from the outside to the inside formed after oxidation at 973 K without changing the main body of the TiAl_3-rich coating. The oxidation kinetics followed parabolic relations during the stable state stage of the isothermal oxidation; the activation energy for oxidation of the coating was calculated as 323 kJ mol~(-1). The hot-dip aluminizing coating provided high protective-ness for the Ti-6.5Al-1Mo-1V-2Zr alloy at 973 K and lower. The oxidation performance of the TiAl_3-rich coating was discussed in detail.