Impact of grain shape on the micromechanics-based extraction of single-crystalline elastic constants from polycrystalline samples with crystallographic texture
Impact of grain shape on the micromechanics-based extraction of single-crystalline elastic constants from polycrystalline samples with crystallographic texture
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DOI：
10.1016/j.actamat.2016.09.040
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发表时间：
2017
期刊：
影响因子：
9.4
通讯作者：
M. Tane;Keisuke Yamori;T. Sekino;T. Mayama
中科院分区：
文献类型：
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作者：
M. Tane;Keisuke Yamori;T. Sekino;T. Mayama
本文提出了一种基于细观力学的方法（逆自洽近似），它可以从具有晶体织构的多晶体中提取出单晶的所有独立弹性常数。在所开发的方法中，所有的弹性常数在各向异性多晶体的共振超声光谱测量，并分析的晶体取向和形状的晶粒。然后，一个单一的晶体，再现那些多晶体的弹性常数，确定Eshelby的夹杂物理论和有效介质近似的基础上，考虑到颗粒之间的弹性相互作用，这反映了他们的形状和取向。所开发的方法确定的弹性常数的纯铜和纯镁单晶的多晶体相当精确。用我们的方法得到的弹性常数与用单晶测量的值之间的差异仅为1.1%。相反，应用逆Voigt-Reuss-Hill近似，它不能考虑的弹性相互作用的晶粒形状的影响，导致在一个相对较差的评价纯单晶铜表现出较强的弹性各向异性。这表明，晶粒形状明显地影响表现出高弹性各向异性的晶粒之间的弹性相互作用，并影响提取的单晶弹性常数。从逆自洽近似的实际应用角度出发，阐明了单晶制备困难的AZ 31镁合金的单晶弹性常数。
A micromechanics-based method (“inverse self-consistent approximation”) that can extract all the independent elastic constants of single crystals from those of polycrystals with crystallographic texture was newly developed. In the developed method, all the elastic constants in an anisotropic polycrystal were measured by resonant ultrasound spectroscopy, and the crystallographic orientations and shapes of the grains were analyzed. Then, the elastic constants of a single crystal, which reproduce those of the polycrystal, were determined on the basis of Eshelby's inclusion theory and the effective-medium approximation, taking into account the elastic interaction between the grains, which reflects their shapes and orientations. The developed method determined the elastic constants of pure Cu and pure Mg single crystals from those of polycrystals quite precisely. The differences between the elastic constants obtained using our method and the values measured using single crystals were only ∼ 1%. In contrast, the application of an inverse Voigt–Reuss–Hill approximation, which cannot consider the effect of the grain shape on the elastic interaction, resulted in a relatively poor evaluation for pure single-crystalline Cu which exhibits strong elastic anisotropy. This indicates that the grain shape clearly affects the elastic interaction between the grains exhibiting high elastic anisotropy and influences the extracted single-crystalline elastic constants. In terms of the actual application of the inverse self-consistent approximation, the single-crystalline elastic constants of AZ31 Mg alloy, whose single crystals cannot be prepared easily, were clarified.