Multiple oxidation mechanism of Al and Ti doping Haynes244 alloy under elevated temperature

Yating Li, Xiaolin Li, Yi He, Jiawei Yang, Xiangyu Gao, Ke Hua, Xiangtao Deng, Haifeng Wang

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of equimolar content Al, Ti and their co-addition on the oxidation behavior of Haynes244 alloy were investigated in air at 900–1100 °C for 100 h. The results show that Al and Ti co-addition alloy possesses the optimum oxidation resistance at 1000 °C and 1100 °C, while Al-added alloy exhibits excellent performance at 900 °C. In Haynes244 alloy, the oxidation resistance is mainly attributed to the protective Cr2O3 layer, which prevents the outward diffusion of the alloy elements and the inward diffusion of oxygen. At 1000 and 1100 °C, Cr2O3 produces the volatile CrO3, leading to the peeling of oxides layer, so that the spallation and degree of volatilization of Cr2O3 directly determine the oxidation performance. The diffusion rate of Cr3+ can be accelerated after addition of Ti by producing Cr vacancies, increasing the formation of Cr2O3 and degree of further volatilization. While the existence of Al2O3 formed at grain boundaries hinders the diffusion of Cr3+ and strengthens the adhesion of oxides, decreasing the volatilization and spallation. The co-addition of Ti and Al elements helps the quick formation of a dense Cr2O3 and obstacles destruction of the dense oxide layer caused by volatilization, collectively providing 1Ti1Al alloy excellent oxidation resistance. When temperature decreasing to 900 °C, Cr2O3 is difficult to largely form due to the low thermal diffusion rate of Cr and a dense Al2O3 layer can be only formed in the alloy doped with 2 at.% Al and prevent the further oxidization.

Original languageEnglish
Article number131826
JournalSurface and Coatings Technology
Volume498
DOIs
StatePublished - 15 Feb 2025

Keywords

  • Haynes244 superalloys
  • High temperature oxidation
  • Oxide scale spallation
  • Oxides formation
  • Trace elements

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