Abstract Selective Laser Melted Ti-6Al-4V (as-SLMed) exhibits decreased yield strength, increased work hardening, and increased ductility after heat treatment at 730 °C (HT-730) or 900 °C (HT-900) for 2 h. To understand the change of mechanical properties, in situ high energy X-ray diffraction (HEXRD) is used to examine the phase composition, load partitioning, slip system activity, and dislocation density evolution in all three specimens. The as-SLMed specimen is dominated by martensitic α΄. After heat treatment, α΄ partly or fully decomposes into α+β, reducing the yield strength. In HT-730, β precipitates with confined size show much higher lattice strain than the α΄/α matrix during deformation; in HT-900, the lattice strain difference is mostly eliminated. This is a key reason for the increased ductility in HT-900. From the anisotropic lattice strain development, basal slip is identified as the easiest slip system in α΄/α. Using an elasto-plastic self-consistent (EPSC) model, the critical resolved shear stress ratio between prismatic slip and basal slip (CRSSprism/CRSSbasal) is estimated to be 1.31 and 1.16 in the as-SLMed and the HT-900 specimens, respectively. The α phase in HT-900 is able to activate multiple slip systems and accumulate more dislocations during plastic deformation. This explains why HT-900 has better ductility and higher work hardening rate than the other two specimens.

中文翻译：

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通过原位 X 射线表征热处理对选择性激光熔化 Ti-6Al-4V 拉伸行为的影响

摘要 选择性激光熔化 Ti-6Al-4V (as-SLMed) 在 730 °C (HT-730) 或 900 °C (HT-900) 热处理 2 小时后屈服强度降低，加工硬化增加，延展性增加. 为了了解机械性能的变化，原位高能 X 射线衍射 (HEXRD) 用于检查所有三个试样的相组成、载荷分配、滑移系统活动和位错密度演化。SLMed 试样主要是马氏体α΄。热处理后，α΄部分​​或全部分解成α+β，降低屈服强度。在 HT-730 中，尺寸受限的 β 析出物在变形过程中表现出比 α΄/α 基体高得多的晶格应变；在HT-900中，晶格应变差大部分被消除。这是 HT-900 延展性增加的一个关键原因。从各向异性晶格应变发展来看，基底滑移被认为是 α΄/α 中最容易的滑移系统。使用弹塑性自洽 (EPSC) 模型，估计在 as-SLMed 和 HT-900 试样中棱柱滑移和基底滑移之间的临界解析剪应力比 (CRSSprism/CRSSbasal) 分别为 1.31 和 1.16 . HT-900 中的 α 相能够激活多个滑移系统并在塑性变形过程中积累更多位错。这就解释了为什么 HT-900 比其他两种试样具有更好的延展性和更高的加工硬化率。分别在 as-SLMed 和 HT-900 试样中为 16。HT-900 中的 α 相能够激活多个滑移系统并在塑性变形过程中积累更多位错。这就解释了为什么 HT-900 比其他两种试样具有更好的延展性和更高的加工硬化率。分别在 as-SLMed 和 HT-900 试样中为 16。HT-900 中的 α 相能够激活多个滑移系统并在塑性变形过程中积累更多位错。这就解释了为什么 HT-900 比其他两种试样具有更好的延展性和更高的加工硬化率。