Effects of fluorined treatment on high temperature oxidation behaviors of γ-TiAl alloy

摘要

Intermetallic γ-TiAl can be used as large structure material in aerospace engines manufacturing, its working temperature limit is 700° C, and it was found that using plasma based ions injection (PBII) and chemical deposition method NH_4F solution on γ-TiAl alloy surface to meet the higher resistance with high temperature oxidation performance requirements, because of its prompting in alloy surface with rich fluorine layer, the treatment can improve the high temperature resistance performance of γ-TiAl alloy. In this paper, γ-TiAl samples were fluorined treated by NH_4F solution and CF_4 PBII. The high temperature oxidation behaviors at 850 °C and 900 °C, also the effect of F~+ concentration and on oxide layer microstructure of γ-TiAl alloy were investigated. The results show that the high temperature oxidation resistance of alloy treated by fluorined treatment is higher than that of untreated sample. The oxidation resistance of treated alloy increases with F~+ concentration at 850°C oxidation, while the oxidation resistance of treated alloy is independent with F~+ concentration at 900°C oxidation. According to SEM results, the microstructure of high temperature oxide layer of treated alloy is compacter than that of untreated sample. Fluoride treatments will play a positive role to improve the high temperature oxidation resistance of γ-TiAl alloy.