Gradient TiZrN coating and deformation-enhanced pretreatment to improve the anti-solid particle erosion and fatigue performance of Ti-6Al-4V alloy

The pronounced notch sensitivity of titanium alloy blades significantly limits their service life in dusty environments. This study investigates the effects of a gradient TiZrN/TiZr coating combined with shot peening strengthening treatment on the resistance to solid particle erosion and fatigue performance. Utilizing first principles calculations, finite element simulations, and electron backscatter diffraction analysis, we analyze the intrinsic mechanisms underlying the strengthening effects of this composite treatment. Solid particle erosion testing demonstrates that gradient TiZrN/TiZr coatings effectively protect titanium alloys from damage at low and high attack angles. The fatigue test results reveal that the composite treatment substantially enhances the fatigue resistance of the titanium alloy, increasing the fatigue limit from 512.5 MPa for the titanium alloy substrate to 617.5 MPa, representing a 20.48 % improvement. First principles calculations and finite element simulations indicate that nitride coatings composed of double transition metal elements can reduce the proportion of covalent bonds within the system by introducing metallic bonds while maintaining surface strength. Additionally, the TiZr metal sublayer in the gradient coating plays a critical role in effectively transferring stress and absorbing impact energy. Consequently, the gradient coating exhibits commendable overall strength and toughness characteristics. Electron backscatter diffraction analysis confirms that the Schmid factor frequency of the titanium alloy decreases following shot peening treatment, indicating that this post-processing strengthening method effectively suppresses the activation of slip systems and the initiation of fatigue cracks. These findings underscore the efficacy of strain-strengthening pretreatment in composite gradient TiZrN/TiZr coatings, highlighting its synergistic role in enhancing solid particle erosion resistance and fatigue performance in titanium alloys.