Influences of the composition design on the microstructure and properties of laser additive manufacturing TiAl alloy coatings

The utilization of titanium aluminide (TiAl) alloys is widespread in the high-temperature sectors of the aerospace industry, despite their challenging manufacturing process and inherent low toughness. Laser additive manufacturing (LAM), as a solution to these challenges, enhances the capability to form complex components and mechanical properties. The influence of process parameters, heat treatment methods, and reinforcing components on the microstructure of TiAl alloys was studied during the LAM process. The principles of designing TiAl alloys were emphasized from the action mechanism of reinforcing components. A classification standard for the component design was proposed based on the different roles of β-stabilizing elements, α-stabilizing elements, rare earth elements, and composites (a combination of the aforementioned components). Furthermore, the work discussed the evolution mechanism of the microstructure and the strengthening mechanism of mechanical properties in TiAl alloys prepared using LAM. These included solid solution strengthening, precipitation strengthening, grain boundary strengthening, grain refinement, and lattice distortion toughening. Finally, future research directions in LAM TiAl alloys were proposed—the innovative design of TiAl alloys through the structural or interfacial control, the development of multiscale characterization techniques for microstructures, and the advancement of high-performance TiAl alloys using data-driven machine learning approaches.