Wear Resistance of Cr-Al-Y Co-Deposition Coatings on TiAl-Nb Based Alloy at 20 °C and 600 °C

The work aims to improve wear resistance of TiAl-Nb based alloy. In this paper, Y modified Cr-Al coating was prepared on TiAl-Nb based surface by taking NH₄Cl as catalyst and diffusing and co-penetrating Cr-Al-Y for 2 h under 1050 ℃. Through the comprehensive application of scanning electron microscopy (SEM), X-ray diffraction (XRD) phase characterization, and energy-dispersive spectroscopy (EDS) compositional analysis, this study systematically investigated the structural characteristics of the diffusion coating layer's microstructure, including phase composition and elemental distribution, and the friction and wear properties of both base alloy and the coatings. The results showed that Cr-Al-Y coatings were provided with a multi-layer composite structure. The outer layers of the Cr-Al-Y coatings prepared at 1050 °C for 2 h were mainly composed of TiCr₂, TiCr, Ti₄Cr and (Ti, Nb)Cr₄ phase. The inner layers of Cr-Al-Y coatings were mainly composed of Ti₂Al phase, and the Interdiffusion zone were mainly composed of Nb-rich γ-TiAl phase. The hardness test showed that the microhardness of the Cr-Al-Y layer gradually decreases from the outer layer to the inner layer, but it was higher than that of the TiAlNb9 alloy. Friction and wear tests indicated that at 20 °C, both the friction coefficient and wear rate of the Cr-Al-Y coating were significantly lower than those of the TiAl-Nb based alloy. At 600 °C, the friction coefficient and wear rate of the coating increased to a certain extent, but they were still lower than those of TiAl-Nb based alloy, showing excellent anti-friction performance. The wear mechanism of TiAl-Nb based alloy at 20 °C was plough wear and slight abrasive wear. At 600 ℃, the wear degree of the alloy increases, and the plough wear and abrasive wear were more obvious. The wear mechanism of Cr-Al-Y layer at 20 °C and 600 °C was delamination wear, adhesive wear and slight abrasive wear. At 20 °C, only the outer layer was damaged, and the inner layer was also damaged at 600 °C, but it still played a protective role in the matrix. The presence of Cr-Al-Y coating significantly improved the friction and wear resistance of TiAl-Nb based alloy at room temperature and high temperature.