论文标题
同步加速器X射线衍射揭示的六角形TI-7AL中晶粒分辨的温度依赖性各向异性
Grain-Resolved Temperature-Dependent Anisotropy in Hexagonal Ti-7Al Revealed by Synchrotron X-Ray Diffraction
论文作者
论文摘要
六边形金属具有热膨胀的各向异性系数，导致加热过程中晶粒水平的内部应力。高能X射线衍射显微镜是一种非破坏性的原位，微观机械和微结构表征技术，已用于确定Ti-7al热膨胀（CTE）的各向异性系数。收集了两个样品的多晶$α$α$ phase ti-7al，从室温到850 $^\ circ $ c连续加热，同时收集了远场上的HEDM扫描。结果表明，“ A”和“ C”方向中CTE的比率发生了变化，这解释了文献中发现的差异。 CTE另外似乎还受到$α_2$沉淀的溶解的影响。晶粒分辨的微机械数据的分析还表明，晶粒尺度应力的重新配置可能是由于各向异性膨胀驱动晶体学滑移所致。
Hexagonal metals have anisotropic coefficients of thermal expansion causing grain-level internal stresses during heating. High energy x-ray diffraction microscopy, a non-destructive, in situ, micromechanical and microstructural characterization technique, has been used to determine the anisotropic coefficients of thermal expansion (CTEs) for Ti-7Al. Two samples of polycrystalline $α$-phase Ti-7Al were continuously heated from room temperature to 850 $^\circ$C while far-field HEDM scans were collected. The results showed a change in the ratio of the CTEs in the 'a' and 'c' directions which explains discrepancies found in the literature. The CTE additionally appears to be affected by the dissolution of $α_2$ precipitates. Analysis of the grain-resolved micromechanical data also shows reconfiguration of the grain scale stresses likely due to anisotropic expansion driving crystallographic slip.
