设计PBF-LB制备的均匀Ti-Nb-Fe-Sn $\beta$钛合金：一种预合金粉末混合策略
Designing Homogeneous Ti-Nb-Fe-Sn $β$ Titanium Alloys by PBF-LB: A Pre-Alloyed Powder Blend Strategy
- Universidade Estadual de Campinas (UNICAMP)（坎皮纳斯州立大学）
- Charles University（查理大学）
- Federal Institute of Education, Science and Technology of São Paulo (IFSP)（圣保罗联邦教育、科学和技术学院）
- Institute of Thermomechanics, Czech Academy of Sciences（捷克科学院热力学研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过预合金粉末混合、大层厚重熔及热处理，制备出成分均匀的Ti-Nb-Fe-Sn $\beta$钛合金，并阐明成分变化对晶粒长大和力学性能的影响。
AI中文摘要：
亚稳态$\beta$钛合金因其低弹性模量、高比强度和优异的耐腐蚀性，在生物医学和结构应用中颇具吸引力。激光粉末床熔融（PBF-LB）通过粉末混合能够实现复杂形状的制造和可控的成分变化。然而，加工元素Ti-Nb混合粉末常因Nb富集颗粒的不完全溶解和非平衡相形成而导致化学不均匀性。为解决这一问题，使用Ti-42Nb、Ti-20Nb-15Fe和Ti-20Nb-20Sn母合金粉末与商业纯Ti混合，通过PBF-LB制备了低模量Ti-Nb-Fe-Sn合金。采用不常见的70 $\mu$m大层厚并伴随层重熔，随后在1000 $°$C下热处理2小时并水淬，制备了Ti-23Nb-3Fe-4Sn、Ti-26Nb-2Fe-4Sn、Ti-29Nb-1Fe-4Sn和Ti-32Nb-4Sn合金。热处理后，所有合金均表现出低孔隙率、均匀的化学分布和单一$\beta$相微观组织，主要为等轴晶粒和弱晶体织构。热力学计算表明，仅凭凝固描述符无法解释非单调的晶粒尺寸演变，这归因于继承的凝固组织、瞬态TiFe类相形成、Nb/Sn偏析和/或溶质拖曳控制的$\beta$晶粒长大。硬度和屈服强度随Fe含量降低和Nb含量增加而下降，分别从268降至224 HV和从691降至468 MPa。通过共振超声光谱法测定的杨氏模量范围为63-81 GPa。这些结果表明，预合金母合金混合粉末结合重熔和热处理，为生产化学均匀的Ti-Nb-Fe-Sn $\beta$合金提供了有效途径，同时揭示了小的成分变化如何控制晶粒长大行为和力学响应。
英文摘要：
Metastable $β$ titanium alloys are attractive for biomedical and structural applications owing to their low elastic modulus, high specific strength, and excellent corrosion resistance. Laser powder bed fusion (PBF-LB) enables complex-shape production and controlled compositional variation through powder blending. However, processing elemental Ti-Nb blends often results in chemical heterogeneity from incomplete dissolution of Nb-rich particles and non-equilibrium phase formation. To address this, low-modulus Ti-Nb-Fe-Sn alloys were produced by PBF-LB using Ti-42Nb, Ti-20Nb-15Fe, and Ti-20Nb-20Sn master-alloy powders blended with commercially pure Ti. Ti-23Nb-3Fe-4Sn, Ti-26Nb-2Fe-4Sn, Ti-29Nb-1Fe-4Sn, and Ti-32Nb-4Sn were fabricated using an uncommonly large 70 $μ$m layer thickness with layer remelting, followed by heat treatment at 1000 $°$C for 2 h and water quenching. After heat treatment, all alloys exhibited low porosity, homogeneous chemical distribution, and single $β$-phase microstructures with predominantly equiaxed grains and weak crystallographic texture. Thermodynamic calculations indicated that solidification descriptors alone could not explain the non-monotonic grain-size evolution, which was attributed to inherited solidification structure, transient TiFe-like phase formation, Nb/Sn partitioning, and/or solute-drag-controlled $β$-grain growth. Hardness and yield strength decreased with decreasing Fe and increasing Nb contents, from 268 to 224 HV and 691 to 468 MPa, respectively. Young's modulus, determined by resonant ultrasound spectroscopy, ranged 63-81 GPa. These results demonstrate that pre-alloyed master-alloy blends combined with remelting and heat treatment provide an effective route for producing chemically homogeneous Ti-Nb-Fe-Sn $β$ alloys while revealing how small compositional changes govern grain-growth behavior and mechanical response.
