In this study, we performed heat treatment with different solution cooling routes and aging heating rates were performed on the TB18 alloy (Ti-5.3Cr-4.9Mo-4.9V-4.3Al-0.9Nb-0.3Fe) to enhance its mechanical properties via ω-assisted nucleation. The results showed that the intragranular α plates that precipitated during aging appeared finer under slow heating than under fast heating because the ω_iso particles formed during the slow heating process provide abundant ω/β interfaces, which can serve as heterogeneous nucleation sites for α precipitates and reduce the nucleation driving force. The corresponding phase transformation sequence is expected to be β + ω_ath → β + ω_ath + ω_iso → β + ω_iso + α → β + α during continuous heating. Further comparing the microstructures, we found that a faster solution cooling rate is more conducive to ω-assisted nucleation. During ω-assisted nucleation, the three-phase orientation relationship holds for: ($11\bar{2}0$)_ω//(0001)_α//(110)_β, and [0001]_ω//[$11\bar{2}0$]_α//[$1\bar{1}1$]_β. At the atomic scale, the ω/α interface appeared as a relatively straight atomic plane, whereas more defects, termed as disconnections, were observed at the α/β interface. Moreover, appropriate ω-assisted nucleation could enhance the ductility of the TB18 alloy without reducing its strength to obtain the optimal comprehensive mechanical properties, and the corresponding fracture mechanism was a mixed mode dominated by ductile fracture. Excessive ω-assisted nucleation could considerably strengthen the alloy but significantly deteriorated its ductility, and the mixed fracture mode was more inclined to brittle fracture.

在这项研究中，我们对 TB18 合金（Ti-5.3Cr-4.9Mo-4.9V-4.3Al-0.9Nb-0.3Fe）进行了不同固溶冷却路线的热处理，并通过时效加热速率提高了其力学性能。 ω-辅助成核。结果表明，时效过程中析出的晶内α板在慢速加热下比在快速加热下显得更细，这是因为慢速加热过程中形成的_ωiso粒子提供了丰富的ω/β界面，可以作为α析出相的异相形核位点和降低成核驱动力。对应的相变序列预计为 β + ω _ath → β + ω _ath  + ω _iso → β + ω _iso + α → β + α 在连续加热期间。进一步比较微观结构，我们发现更快的固溶冷却速率更有利于ω辅助成核。在 ω 辅助成核过程中，三相取向关系适用于： ($11\bar{2}0$) _ω //(0001) _α //(110) _β和 [0001] _ω //[$11\bar{2}0$] _α //[$1\bar{1}1$] _β . 在原子尺度上，ω/α界面表现为一个相对直的原子平面，而在α/β界面观察到更多的缺陷，称为断开。此外，适当的ω辅助形核可以在不降低其强度的情况下提高TB18合金的延展性，从而获得最佳的综合力学性能，相应的断裂机制为以延性断裂为主的混合模式。过度的ω辅助形核可以显着强化合金但显着降低其延展性，混合断裂模式更倾向于脆性断裂。