In recent years, the Ti₂AlNb-based alloys are selected as potential alloys for elevated temperature applications to replace conventional Ni-based superalloys owing to their good creep resistance and oxidation resistance which are related to the O precipitates. In this paper, the precipitation mechanisms of O phase, phase transformation and microstructure control of Ti₂AlNb-based alloys are reviewed. Ti₂AlNb-based alloys generally consist of B2/β, α₂, and O phase with different morphologies which are derived from the various heat treatment processes, including equiaxed α₂/O particles, bimodal microstructure, and Widmannstätten B2/β + O structures etc. As a newly developed strengthening phase, O precipitates can be precipitated from the B2/β matrix or α₂ phase directly as well as generated by means of peritectoid reaction of α₂ phase and bcc matrix. Microstructural control of the Ti₂AlNb-based alloys can be implemented by refining the original B2/β grain size and regulating the O precipitates. Multidirectional isothermal forging (MIF) and powder metallurgy technique are two effective methods to refine the original B2/β grains and the morphology and size of O precipitates can be regulated by adding alloying components and pre-deformation process. Moreover, the phase diagram as well as coarsening behavior of Ti₂AlNb-based alloys in ageing process is also reviewed. For the further application of these alloys, more emphasis should be paid on the deep interpolation of microstructure-property relationship and the adoption of advanced manufacturing technology.

近年来，由于与O析出物有关的良好的抗蠕变性和抗氧化性，Ti ₂ AlNb基合金被选作高温应用的潜在合金，以代替常规的Ni基高温合金。本文综述了Ti ₂ AlNb基合金的O相析出机理，相变及组织控制。的Ti ₂ AlNb基合金通常由B2 /β的，α ₂，并用它们从各种热处理过程衍生，包括等轴α不同的形态O相₂/ O颗粒，双峰显微组织，魏氏B2 /β+ O结构等。作为新开发的强化相，O-沉淀物可以从B2沉淀/β基质或α ₂相直接以及通过包析反应的装置产生α ₂相和BCC矩阵。Ti ₂ AlNb基合金的微结构控制可通过细化原始B2 /β晶粒尺寸并调节O析出物来实现。多方向等温锻造和粉末冶金技术是提纯原始B2 /β晶粒的两种有效方法，可通过添加合金成分和预变形工艺来调节O析出物的形貌和尺寸。此外，Ti ₂的相图及粗化行为还对时效过程中的AlNb基合金进行了综述。为了进一步应用这些合金，应更加重视深层组织与性能之间的内插关系以及采用先进的制造技术。