Study on Fatigue Behavior and Fracture Mechanism of LMD Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy Based on Microstructure.

This study explores the fatigue behavior and fracture mechanisms of TC11 titanium alloy formed by laser metal deposition (LMD) and subjected to double annealing. The research focuses on how the alloy's unique microstructure, consisting of alternating equiaxed and columnar crystals, influences its fatigue performance. The microstructure's basket-like α' phase, made up of both plate-shaped and needle-like structures, leads to variations in crack growth behavior, as shown in the relationship between the crack growth rate and the stress intensity. An analysis of slip patterns reveals that equiaxed crystals undergo more frequent deformation, accelerating crack propagation compared to the more evenly distributed deformation in columnar crystals. These findings suggest a new approach for improving the fatigue resistance of 3D-printed titanium alloys by optimizing their microstructure. This study provides valuable insights for enhancing material toughness and extending the lifespan of titanium alloys in applications such as aerospace and biomedical engineering.