A new near β-Ti alloy Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe (Ti-5321) with a unique combination of high strength and good fracture toughness was designed. The microstructure was tailored by changing the solution and ageing conditions, and the influences of microstructural evolution on tensile properties and fracture toughness of the alloy were investigated. The results showed that the volume fraction and size of primary α phase were decreased with increasing the solution temperature, while the morphology of secondary α precipitates was related to ageing temperature. The ultimate tensile strength (UTS), total elongation (EL) and fracture toughness can be achieved in a range of 1147–1439 MPa, 3–26% and 57–76 MPa m^1/2, respectively, depending on the heat treatment parameters. An excellent balance of high strength and good ductility was realized after the solution treatment at 830 °C and ageing at 620 °C for 480 min, in which the UTS, EL and fracture toughness were 1238 MPa, 20% and 73 MPa m^1/2, respectively. Morphological features of the fractography were discussed against the different microstructural morphologies, and this provided further information on the fracture behavior of the alloy.

设计了一种新型的近β-Ti合金Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe（Ti-5321），具有高强度和良好的断裂韧性的独特组合。通过改变固溶和时效条件来定制显微组织，并研究了显微组织演变对合金的拉伸性能和断裂韧性的影响。结果表明，随着固溶温度的升高，初生α相的体积分数和尺寸减小，而次生α相的形貌与时效温度有关。极限拉伸强度（UTS），总伸长率（EL）和断裂韧性可在1147-1439 MPa，3-26％和57-76 MPa m ^1/2的范围内实现分别取决于热处理参数。在830°C固溶处理和620°C时效480 min时，实现了高强度和良好延展性的极佳平衡，其中UTS，EL和断裂韧性分别为1238 MPa，20％和73 MPa m ^{1 / 2}，分别。针对不同的微观结构形态讨论了形貌的形貌特征，这为合金的断裂行为提供了进一步的信息。