Strengthening mechanisms in AlCoCrFeNiMo0.8–TiC composite coating based on first-principles calculations.

The excellent hardness and wear resistance of AlCoCrFeNiMo_0.8–TiC composite coating benefit from various strengthening mechanisms, including fine grain strengthening, dislocation strengthening, load transfer strengthening, solid solution strengthening, and precipitation strengthening. To analyze their contributions in the strength and hardness, an accurate prediction model is essential. In this work, a prediction model for the hardness increment was established based on some key elastic constants calculated by the first-principles. Subsequently, the contributions of strengthening mechanisms were quantitatively evaluated by the developed prediction model. It was found that the Young's modulus and shear modulus for B2 phase were 179.65 GPa and 67.36 GPa, respectively, and those of σ phase were 354.08 GPa and 139.19 GPa, respectively. The precipitation strengthening was the predominant mechanism in the composite coating, with a strength contribution of 736.4 MPa and a hardness contribution of 225.2 HV, which accounted for 76.2% of the contribution values. The prediction model has high accuracy, which is evidenced by the small relative error (9.1%) between the total theoretical hardness contribution (295.2 HV) and the Vickers hardness tested by nanoindentation (322.1 HV). The AlCoCrFeNiMo_0.8–TiC composite coating has various strengthening mechanisms. To quantitatively analyze these contributions on the hardness, a prediction model is established based on the elastic moduli obtained by the first-principles calculations. [ABSTRACT FROM AUTHOR]