Significant grain refinement of β grains in metastable β TB2 titanium alloy (Ti–8Cr–3Al–5Mo–5V) was achieved through the minor addition of zirconium diboride (ZrB₂) during laser melting deposition (LMD). The size of β grains decreased from ∼150 μm in the as-deposited TB2 alloy to ∼70 μm in TB2+0.5ZrB₂ (TB2 with 0.5 wt.% ZrB₂ addition) alloy. This study demonstrates that TB2+0.5ZrB₂ exhibits good combination of ultimate tensile strength (UTS ≈ 896 MPa) and ductility (EL ≈ 15%) in comparison to the as-deposited TB2 (UTS ≈ 811 MPa and EL ≈ 18%). At similar strength (UTS≈ 900 MPa), TB2+0.5ZrB₂ shows superior ductility than TB2+0.4Zr+0.1B and TB2+0.1B because of the formation of fine TiB particles (length of ∼0.6 μm) by uniformly introducing boron (B) into TB2 and lower diffusion rate of B. The excellent mechanical properties of TB2+0.5ZrB₂ are attributed to the synergistic effect of strengthening from refined β grains and fine-scale TiB precipitation. The mechanism associated with refinement of β grains is elucidated and discussed in the context of relevant phase diagrams.

通过在激光熔化沉积 (LMD) 过程中少量添加二硼化锆 (ZrB ₂ )实现了亚稳态 β TB2 钛合金 (Ti-8Cr-3Al-5Mo-5V) 中 β 晶粒的显着细化。β 晶粒的尺寸从沉积态 TB2 合金中的～150 μm 减小到 TB2+0.5ZrB ₂（添加 0.5 wt.% ZrB ₂的 TB2 ）合金中的～70 μm。该研究表明，与沉积态的 TB2（UTS ≈ 811 MPa 和 EL ≈ 18%）相比，TB2+0.5ZrB ₂表现出良好的极限抗拉强度（UTS ≈ 896 MPa）和延展性（EL ≈ 15%）。在相似强度下（UTS≈900 MPa），TB2+0.5ZrB ₂与 TB2+0.4Zr+0.1B 和 TB2+0.1B 相比，由于硼 (B) 均匀地引入 TB2 中形成了细小的 TiB 颗粒（长度约为 0.6 μm），并且 B 的扩散速率较低，因此表现出比 TB2+0.4Zr+0.1B 更好的延展性。 TB2+0.5ZrB ₂的性能归因于细化β晶粒强化和细规模TiB析出的协同作用。在相关相图的背景下阐明和讨论了与 β 晶粒细化相关的机制。