Abstract Understanding of the deformation micro-mechanism as a function of grain orientation during cyclic loading is of significant importance to have failure safe design of structural components made of commercially pure titanium (CP-Ti). The evolution of deformation microstructure and texture of commercially pure titanium samples with prismatic-pyramidal (orientation A) and near basal (orientation B) as initial texture along the loading direction has been investigated during load reversal at ±8% and ± 12% strain using in-situ synchrotron X-ray diffraction. The synchrotron X-ray diffraction results have been further complemented with Elastic-Plastic Self-Consistent (EPSC) simulation of the texture data and ex-situ Electron backscatter diffraction (EBSD) scan taken at the same region. Orientation A showed partially reversible texture whereas orientation B showed non-reversible texture with mechanical reversibility. The partial textural reversibility has been attributed to the prism to basal slip transition which toggles the c-axis between the normal and transverse direction during the tension-compression cycle. With an increase in strain from 8 to 12%, microstrain and dislocation density in the basal plane of orientation A decreases sharply. On the other hand, for the same level of strain in orientation B, microstrain increases but the dislocation density of basal plane shows insignificant change. The crystal orientation map obtained from ex-situ EBSD of deformed microstructure complements to the fact indicating, with increase in strain, deformation of basal oriented grains show non-Schmid behaviour of contraction twin propagation due to local strain incompatibility in orientation A. On the other hand, the prism oriented grains of orientation B have mostly deformed by extension twinning, which reorients them towards basal orientation. The deformation proceeds by lateral thickening of twins due to the lower elastic stiffness of the twinned region compared to the grain matrix. The extension twin boundaries get converted to contraction twin boundaries at higher strain during load reversal.

中文翻译：

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使用同步加速器 X 射线衍射原位研究商业纯钛负载反转过程中微观结构和织构的演变

摘要 了解作为循环加载过程中晶粒取向函数的变形微观机制对于商业纯钛 (CP-Ti) 结构部件的故障安全设计具有重要意义。使用棱柱锥（A 方向）和近基部（B 方向）作为初始织构的商用纯钛样品沿加载方向在 ±8% 和 ±12% 应变下在载荷反转期间的变形微观结构和织构的演变研究原位同步加速器 X 射线衍射。同步加速器 X 射线衍射结果得到了对纹理数据的弹塑性自洽 (EPSC) 模拟和在同一区域进行的异位电子背散射衍射 (EBSD) 扫描的进一步补充。方向 A 显示部分可逆纹理，而方向 B 显示具有机械可逆性的不可逆纹理。部分纹理可逆性归因于棱镜到基底滑移的过渡，它在拉伸 - 压缩循环期间在法向和横向之间切换 c 轴。随着应变从 8% 增加到 12%，取向 A 基面中的微应变和位错密度急剧下降。另一方面，对于相同水平的 B 方向应变，微应变​​增加，但基面位错密度变化不大。从变形微观结构的异位 EBSD 获得的晶体取向图补充了事实表明，随着应变的增加，由于取向 A 的局部应变不相容，基底取向晶粒的变形表现出收缩孪晶传播的非施密德行为。另一方面，取向 B 的棱柱取向晶粒主要通过拉伸孪晶变形，这将它们重新定向为基底取向。由于与晶粒基体相比，孪晶区域的弹性刚度较低，因此变形通过孪晶的横向增厚进行。在负载反转期间，拉伸孪晶边界在较高应变下转换为收缩孪晶边界。由于与晶粒基体相比，孪晶区域的弹性刚度较低，因此变形通过孪晶的横向增厚进行。在负载反转期间，拉伸孪晶边界在较高应变下转换为收缩孪晶边界。由于与晶粒基体相比，孪晶区域的弹性刚度较低，因此变形通过孪晶的横向增厚进行。在载荷反转期间，拉伸孪晶边界在较高应变下转换为收缩孪晶边界。