To optimize the (α + β) microstructure and find a trade-off between strength and toughness, Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys were prepared according to Mo_[eq] and d electron theory. Microstructure of α phase and dislocation was observed, and the related mechanisms were determined. Results show that the relative content of β phase increases by adjusting Mo content. Length-width ratios of α_p and α_s phases decrease from 8.8 to 6 and 10.8 to 9.1 as Mo increases from 5 to 6 wt%. When the Mo content increases further, length–width ratio increases. The dislocation density reaches its maximum at 6Mo. The low diffusion rate of Mo and refined β grains causes the refinement of the α phase. The increase of grain boundary and the appearance of lattice distortion increase the dislocation density, but the formation of twins consumes partial dislocation. The tensile strength first increases and then decreases, reaching a maximum of 1326 MPa at 6Mo. The toughness of 6Mo alloy is 85 MPa·m^1/2. The strength increases by 12% while the toughness only decreases by 4%. The precipitation strengthening caused by the optimization of the (α + β) microstructure and the dislocation strengthening caused by the increased dislocations are the determining mechanism of the trade-off between strength and toughness.

为了优化 (α + β) 微观结构并找到强度和韧性之间的权衡，根据 Mo _[eq]和d电子理论制备了 Ti- x Mo-4Al-4Zr-3Nb-2Cr-1Fe 合金。观察了α相和位错的微观结构，并确定了相关机制。结果表明，通过调整Mo含量可以增加β相的相对含量。_{α p}和 α _s的长宽比当 Mo 从 5% 增加到 6% 时，物相从 8.8 减少到 6 和 10.8 减少到 9.1。当 Mo 含量进一步增加时，长宽比增加。位错密度在 6Mo 处达到最大值。Mo的低扩散速率和细化的β晶粒导致α相的细化。晶界的增加和晶格畸变的出现增加了位错密度，但孪晶的形成消耗了部分位错。抗拉强度先增大后减小，在 6Mo 时达到最大值 1326 MPa。6Mo合金的韧性为85 MPa·m ^1/2. 强度增加12%，而韧性仅降低4%。(α+β)显微组织优化引起的析出强化和位错增多引起的位错强化是强度与韧性权衡的决定机制。