Throughout our engineered environment, many materials exhibit a crystalline lattice structure. The orientation of such lattices is crucial in determining functional properties of these structures, including elasticity and magnetism. Hence, tools for determining orientation are highly sought after. Surface acoustic wave velocities in multiple directions can not only highlight the microstructure contrast, but also determine the crystallographic orientation by comparison to a pre-calculated velocity model. This approach has been widely used for the recovery of orientation in cubic materials, with accurate results. However, there is a demand to probe the microstructure in anisotropic crystals - such as hexagonal close packed titanium. Uniquely, hexagonal structure materials exhibit transverse isotropic linear elasticity. In this work, both experimental and simulation results are used to study the discrete effects of both experimental parameters and varying lattice anisotropy across the orientation space, on orientation determination accuracy. Results summarise the theoretical and practical limits of hexagonal orientation determination by linear SAW measurements. Experimental results from a polycrystalline titanium specimen, obtained by electron back scatter diffraction and spatially resolved acoustic spectroscopy show good agreement (errors of ϕ1=5.14° and Φ=6.99°). Experimental errors are in accordance with those suggested by simulation, according to the experimental parameters. Further experimental results demonstrate dramatically improved orientation results (Φ error <1°). Demonstrating the possibility of achieving results near the theoretical limit by strict control of the experimental parameters.

中文翻译：

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用表面声波速度测量确定六方晶体结构材料的晶体取向

在我们的整个工程环境中，许多材料都表现出晶格结构。这种晶格的取向对于确定这些结构的功能特性至关重要，包括弹性和磁性。因此，非常需要用于确定方向的工具。多个方向的表面声波速度不仅可以突出微观结构的对比度，还可以通过与预先计算的速度模型进行比较来确定晶体取向。这种方法已被广泛用于立方体材料的取向恢复，结果准确。然而，需要探测各向异性晶体的微观结构 - 例如六方密堆积钛。独特的六边形结构材料表现出横向各向同性的线性弹性。在这项工作中，实验和模拟结果都用于研究实验参数和整个取向空间的晶格各向异性变化对取向确定精度的离散影响。结果总结了通过线性 SAW 测量确定六边形取向的理论和实际限制。通过电子背散射衍射和空间分辨声学光谱获得的多晶钛样品的实验结果显示出良好的一致性（φ1=5.14° 和 Φ=6.99° 的误差）。根据实验参数，实验误差与模拟所建议的一致。进一步的实验结果表明定向结果得到显着改善（Φ 误差 <1°）。