The tread-off between the strength and ductility of near-β titanium alloys has significantly limited their applications. In this study, a novel near-β titanium alloy containing Si element was designed, and the influence of α-phase spheroidization and silicide precipitation on the mechanical properties was investigated during isothermal multi-directional forging (IMDF) process. The results showed that the β grain is easy to deform and elongate, and the deformed alloy mainly undergoes dynamic recovery (DRV) rather than dynamic recrystallization (DRX). Some silicides are dissolved due to the temperature rise caused by IMDF and the diffusion of atoms on the top of the irregularly shaped silicides. Zr and Si elements are redistributed and segregated at the dislocation, resulting in the formation of submicron-scale and nano-scale silicides. Lath-like α_p phase will precipitate from the prior β grain after heat treatment in the dual-phase region, and the volume fraction of α_p phase increases with the decrease of heat treatment temperature. In addition, rotation deformation and spheroidization of the lath-like α_p phase occur during multi-pass IMDF in the dual-phase region. When multi-pass IMDF temperature is 770 ℃, the silicide distribution is uniform, and the α_p phases are equiaxed, which is conducive to the improvement of ductility. The obtained results provide a new way to prepare the Si-containing near-β titanium alloys with excellent mechanical properties.

中文翻译：

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新型近β钛合金在等温多向锻造过程中的硅化物沉淀机理和αp相的球化行为


近β钛合金的强度和延展性之间的偏差极大地限制了它们的应用。本研究设计了一种新型含硅元素的近β钛合金，研究了等温多向锻造 （IMDF） 过程中α相球化和硅化物沉淀对力学性能的影响。结果表明，β晶粒易变形和伸长，变形合金主要经历动态恢复 （DRV） 而不是动态再结晶 （DRX）。由于 IMDF 引起的温度升高和原子在不规则形状的硅化物顶部的扩散，一些硅化物被溶解。Zr 和 Si 元素在位错处重新分布和偏析，导致形成亚微米级和纳米级硅化物。在双相区热处理后，前β晶粒会析出板条状α_p相，且α_p相的体积分数随热处理温度的降低而增加。此外，在双相区域的多通道 IMDF 过程中，板条状 α_p 相的旋转变形和球化会发生。当多通道 IMDF 温度为 770 °C 时，硅化物分布均匀，α_p 相呈等轴状，有利于延展性的提高。所得结果为制备具有优异力学性能的含硅近β钛合金提供了一种新方法。