Titanium-based biomaterials are the gold standard for orthopedic implants; however, they are not generally suitable for the manufacture of intravascular stents. Their low strength-ductility trade-off and low work hardening rate are their main limitations. However, Ni-free alloys are desirable for such application in order to avoid allergic reactions caused by the high Ni-content materials currently applied. Therefore, in this study, three alloys of the Ti-Mo-Fe system (Ti-8Mo-2Fe, Ti-9Mo-1Fe and Ti-10.5Mo-1Fe) were designed to present high strength-ductility compromise and high work hardening rate. Their microstructures, mechanical properties and plastic deformation mechanism were investigated. Athermal ω precipitates were observed in the β matrix of all solution-treated alloys. In the solution-treated β matrix of the Ti-9Mo-1Fe alloy, additional nanometer-sized α" particles were detected by transmission electron microscopy (TEM). Although the combined TWIP/TRIP effects were expected by the design method on the Ti-8Mo-2Fe and Ti-9Mo-1Fe alloys, no TRIP effect was actually observed. In fact, stress-induced martensitic (SIM) transformation occurred mainly at the {332}<113> twins/matrix interfaces for all the strained microstructures and acted as a localized stress-relaxation mechanism, delaying the fracture. Based on the electron backscatter diffraction (EBSD) analyses, in the Ti-8Mo-2Fe and Ti-10.5Mo-1Fe alloys, the formation of a dense network of {332}<113> twins was responsible for their high and steady work hardening rates (1370 and 1120 MPa) and large uniform elongations (22 and 34%). The absence of SIM α" as the primary mechanism of plastic deformation and solid solution hardening of Fe resulted in their high strengths (yield strength of 772 and 523 MPa). In Ti-9Mo-1Fe, the formation of mechanical twinning was hindered, resulting in limited strain-hardening capability and low uniform elongation (6%). The nanometer-sized α" particles in its β matrix along with the athermal ω precipitates are thought to impair the mechanical twinning and the ductility of this alloy.

钛基生物材料是骨科植入物的黄金标准；然而，它们通常不适合制造血管内支架。它们的低强度-延展性权衡和低加工硬化率是它们的主要限制。然而，此类应用需要无镍合金，以避免由目前应用的高镍含量材料引起的过敏反应。因此，在本研究中，设计了 Ti-Mo-Fe 系的三种合金（Ti-8Mo-2Fe、Ti-9Mo-1Fe 和 Ti-10.5Mo-1Fe）来呈现高强度-延展性折衷和高加工硬化率。对其微观结构、力学性能和塑性变形机理进行了研究。在所有固溶处理合金的 β 基体中观察到非热 ω 沉淀物。在固溶处理的Ti-9Mo-1Fe 合金的β 基体中，通过透射电子显微镜 (TEM)检测到额外的纳米尺寸的α" 颗粒。虽然设计方法预期Ti- 8Mo-2Fe 和 Ti-9Mo-1Fe 合金，实际上没有观察到 TRIP 效应。事实上，应力诱发马氏体 (SIM) 转变主要发生在 {332}<113> 孪晶/基体界面应变微观结构并作为局部应力松弛机制，延迟断裂。基于电子背散射衍射 (EBSD) 分析，在Ti -8Mo-2Fe 和 Ti-10.5Mo-1Fe 合金中，{332}<113> 孪晶的致密网络的形成是其高稳定加工硬化的原因率（1370 和 1120  MPa）和大的均匀伸长率（22 和 34%）。由于没有 SIM α" 作为Fe塑性变形和固溶硬化的主要机制，因此它们的强度很高（屈服强度分别为 772 和 523 MPa）。在 Ti-9Mo-1Fe 中，阻碍了机械孪晶的形成，导致在有限的应变硬化能力和低 均匀伸长率（6%）。其β基体中的纳米尺寸 α" 粒子以及无热 ω 沉淀物被认为会损害该合金的机械孪晶和延展性。