Tribological Properties of γ-TiAl Alloy Fretting against Nickel-Based Superalloy at Elevated Temperature

The tribological properties of γ-TiAl alloys under sliding condition have been well established, but the mechanisms for fretting wear, especially at elevated temperature, remain to be further clarified. In the present study, the tribological behaviors and mechanisms of a γ-TiAl alloy were investigated under an elevated temperature fretting condition. The wear scars, debris, and tribolayers were studied with scanning electron microscope, energy dispersive spectrometer, and Raman spectrometer. The structural and mechanical properties of the tribolayers were investigated utilizing transmission electron microscope and nanoindentation tests. The results demonstrated that the severe adhesive wear, delamination, and abrasive wear in the early stage of fretting resulted in high wear rate of the γ-TiAl alloy. As fretting progresses, the formation of tribolayers with nanograins and excellent mechanical properties improved the fretting wear resistance of the γ-TiAl alloy. Due to the protective effect of the adhesively transferred γ-TiAl, the wear rate of the nickel-based superalloy counterpart was significantly lower.