The design of materials with good strength and ductility is still a challenge to current materials science. Here, we propose a two-step aging method to balance the comprehensive mechanical properties in near-β titanium alloys by designing multiscale α precipitate distribution. Phase-field calculations in Ti-V binary alloys are used to screen the heat treatment process by changing the microstructure. Our calculations show that the coarse α precipitates nucleate near grain boundaries at 650°C first and grow and nucleate to the grain interior with the increase of aging time. The fine α precipitates nucleate and grow in grain after subsequent aging at 550°C, and the whole system shows four different microstructures in grain by changing the aging time, i.e., homogeneous fine α precipitates, coarse α precipitates surrounded by fine α precipitates, fine α precipitates surrounded by coarse α precipitates, and homogeneous coarse α precipitates. Based on this strategy, we design a hierarchical α precipitate microstructure in Ti55531 alloy by two-step aging at 650°C/60 min plus 550°C/180 min, which shows enhanced mechanical properties with the ultimate tensile strength of 1.38 GPa and total elongation of 6%. Our work sheds light on the design of novel Ti alloys with comprehensive strength and ductility properties by heterogeneous microstructure.

设计具有良好强度和延展性的材料仍然是当前材料科学的一个挑战。在这里，我们提出了一种两步时效方法，通过设计多尺度α沉淀分布来平衡近β钛合金的综合力学性能。Ti-V 二元合金中的相场计算用于通过改变微观结构来筛选热处理过程。我们的计算表明，粗 α 析出物在 650°C 时首先在晶界附近成核，并随着时效时间的增加长大并成核到晶粒内部。细小α相在550℃时效后在晶粒内成核长大，随着时效时间的改变，整个体系在晶粒中呈现出四种不同的显微组织，即均质的细小α相、粗α相被细小α相包围、细小的 α 析出物被粗的 α 析出物包围，均匀的粗 α 析出物。基于此策略，我们通过 650°C/60 分钟和 550°C/180 分钟的两步时效在 Ti55531 合金中设计了分层 α 析出显微组织，显示出增强的机械性能，极限拉伸强度为 1.38 GPa 和总强度。伸长率 6%。我们的工作阐明了通过异质微观结构设计具有综合强度和延展性的新型钛合金。