Fatigue behavior of in-situ TiB₂/7050Al metal matrix composites: Fracture mechanisms and fatigue life modeling after milling

Due to the superior properties such as low density, improved strength and wear resistance, the in-situ TiB₂/7050Al MMCs have become a series of promising aeronautical materials. However, researches of manufacturing performance and fatigue behavior on machined in-situ TiB₂/7050 Al MMCs have not been widely carried out. In this study, the fatigue behavior of machined in-situ TiB₂/7050Al MMCs specimens such as fatigue mechanism, stress concentration, fatigue life and life modeling were deeply investigated. It was found that the fatigue life ranges from 1.0 × 10⁵ to 4.0 × 10⁶, which turned to be obvious high-cycle fatigue life. With surface roughness increased, the fatigue life decreased sharply. It would be highly significant to reduce the machined surface roughness below 1.0 μm for higher fatigue life. The fracture mechanisms of cutting in-situ TiB₂/7050Al MMCs was found to be brittle fracture due to the existence of fine particles. Besides, a stress concentration model and fatigue life prediction model were established. With validation, the relative errors between prediction model and experiment were smaller than 18% indicating that the proposed fatigue life prediction model of machined in-situ TiB₂/7050Al MMCs was of good reliability and accuracy.