Abstract In this study, the microstructures of three widely used dual-phase titanium alloys: Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-2Sn-4Zr-6Mo are characterized using backscatter electron imaging and the deformation behaviors in their individual α and β phases are investigated using in situ high-energy X-ray diffraction during uniaxial tension experiments. This is accompanied by calculation of the strain rate sensitivity (SRS) in these alloys, as a function of applied loading. The results of the calculated SRS and the mechanical response (in terms of lattice strains and hardening behaviors) are rationalized based on the local microstructure, composition, and texture of the alloy. A stress-induced β (BCC) to α" (orthorhombic) phase transformation is observed during the in-situ diffraction experiment, which permitted analysis of the lattice strain evolution during the phase transformation. Results from this study provide insights into the relationship between microstructure, composition, applied loading, and the deformation behavior, including effects on loading with time holds. Specifically, the results show that the microstructure, and not necessarily the chemical composition (Mo content), along with the applied loading have a dominant role in the observed SRS variation in titanium alloys. Also, the evolution of the α" (orthorhombic) phase is observed for the first time during deformation of an industrially relevant titanium alloy, Ti-6246.

中文翻译：

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双相钛合金力学行为的应变率敏感性、微观结构变化和应力辅助β→α”相变研究

摘要 在这项研究中，三种广泛使用的双相钛合金：Ti-6Al-4V、Ti-6Al-2Sn-4Zr-2Mo 和 Ti-6Al-2Sn-4Zr-6Mo 的显微组织通过背散射电子成像和在单轴拉伸实验中使用原位高能 X 射线衍射研究了它们各自的 α 和 β 相的变形行为。这伴随着这些合金中应变率敏感性 (SRS) 的计算，作为施加的载荷的函数。计算的 SRS 和机械响应（在晶格应变和硬化行为方面）的结果根据合金的局部微观结构、成分和织构进行合理化。在原位衍射实验中观察到应力诱导的 β (BCC) 到 α" (正交) 相变，这允许分析相变期间的晶格应变演变。这项研究的结果提供了对微观结构、成分、施加的载荷和变形行为之间关系的见解，包括随时间保持对载荷的影响。具体而言，结果表明，微观结构，不一定是化学成分（Mo 含量），以及施加的载荷，在观察到的钛合金 SRS 变化中起主导作用。此外，在工业相关钛合金 Ti-6246 变形期间首次观察到 α"（正交）相的演变。包括对加载时间保持的影响。具体而言，结果表明，微观结构，不一定是化学成分（Mo 含量），以及施加的载荷，在观察到的钛合金 SRS 变化中起主导作用。此外，在工业相关钛合金 Ti-6246 变形期间首次观察到 α"（正交）相的演变。包括对加载时间保持的影响。具体而言，结果表明，微观结构，不一定是化学成分（Mo 含量），以及施加的载荷，在观察到的钛合金 SRS 变化中起主导作用。此外，在工业相关钛合金 Ti-6246 变形期间首次观察到 α"（正交）相的演变。