The structure and applications in the materials field of Ti2AlNb alloy: A review

Ti2AlNb alloys have emerged as the most promising candidate material for future aero-engine components and the optimal alternative to nickel-based superalloys, owing to their exceptional specific strength and elevated temperature performance. These performance characteristics are intrinsically linked to the complex phase evolution within Ti2AlNb alloys. This article provides a comprehensive review of the precipitation and transformation mechanisms of different phases in Ti2AlNb alloys and the corresponding microstructural control strategies. By comparing the morphological and performance differences of precipitated phases under various processing routes - including casting, arc melting, forging, and additive manufacturing - we elucidate the intrinsic relationships among processing, microstructure, and properties. The microstructural evolution of Ti2AlNb alloys under different heat treatment regimes is also systematically analyzed. Furthermore, we thoroughly examine the application of Ti2AlNb alloys in laser additive manufacturing processes. We subsequently describe the unique microstructural features of LPBF-fabricated Ti2AlNb alloys and discuss the formation mechanisms of defects such as porosity and cracks, along with corresponding mitigation strategies. Finally, we propose future research directions to advance this field.