Effects of different pack aluminizing fillers on the aluminide coatings of Ti-6Al-4V alloy and their high-temperature oxidation behaviors

The aluminide coating process of Ti-6Al-4V alloys with different fillers(100wt.% Al_2O_3,50wt% Y_2O_3+50wt.% Al_2O_3 and 100wt.% Y_2O_3) for improvement of the oxidation resistance were investigated.The results show that the filler does not only participate in the aluminizing process,but also has much effect on the coating composition.The XRD analysis reveals that the aluminide coating with filler Al_2O_3 is predominant with TiAl_3 and TiAl phases;while the aluminide coatings with filler Y_2O_3+Al_2O_3 are predominant with Ti_3Al phase.The oxidation kinetics shows that different fillers affect greatly the oxidation resistance of aluminide coating,and the oxidation resistance of aluminized specimens with pack aluminizing filler Al_2O_3 are about 5-8 times than that of the aluminized specimens with other pack aluminizing fillers.