Insignificant elastic-modulus mismatch and stress partitioning in two-phase Mg–Zn–Y alloys comprised of α-Mg and long-period stacking ordered phases
Insignificant elastic-modulus mismatch and stress partitioning in two-phase Mg–Zn–Y alloys comprised of α-Mg and long-period stacking ordered phases
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DOI：
10.1016/j.msea.2017.10.069
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发表时间：
2018-01
期刊：
影响因子：
6.4
通讯作者：
M. Tane;Shogo Suzuki;M. Yamasaki;Y. Kawamura;K. Hagihara;H. Kimizuka
中科院分区：
文献类型：
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作者：
M. Tane;Shogo Suzuki;M. Yamasaki;Y. Kawamura;K. Hagihara;H. Kimizuka
研究了由α-Mg和长周期堆积有序相组成的两相Mg-Zn-Y合金的弹性模失配及其应力分配。采用挤压和定向凝固工艺制备了含有各向异性取向的18R或14H型LPSO相的两相多晶和由α-Mg或18R型LPSO相组成的单相多晶，并用共振超声波谱测量了它们的成套各向异性弹性性能。利用EShelby夹杂理论、有效介质近似和逆Voigt-Reuss-Hill近似分析了单相和两相合金的弹性性能，其中考虑了制备过程中形成的晶体织构和微观结构。分析表明，18R-LPSO相的弹性性质并不是唯一的，它们依赖于溶质锌和Y原子的浓度。此外，两相合金中嵌入的18R-LPSO相的弹性模量低于由18R-LPSO单相组成的合金。基于密度泛函理论的第一性原理计算分析表明，低弹性模数是由于嵌入在LPSO相中的短程有序溶质原子团密度低、稳定性差所致。由于LPSO相的弹性模数较低，α-Mg和LPSO相之间的弹性失配和弹性相互作用很小。结果表明，LPSO相的形成对LPSO相的应力分配影响不大，与LPSO相的形态无关。
Elastic-modulus mismatch and the resultant stress partitioning in two-phase Mg–Zn–Y alloys comprised of α-Mg and long-period stacking ordered (LPSO) phases were studied. Two-phase polycrystals containing anisotropically oriented 18R-or 14H-type LPSO phase and single-phase polycrystals consisting of α-Mg or 18R-type LPSO phase were prepared by extrusion and directional solidification processes and their complete sets of anisotropic elastic properties were measured using resonant ultrasound spectroscopy. Elastic properties of the single and two-phase alloys were analyzed using Eshelby's inclusion theory, effective-medium approximation, and inverse Voigt-Reuss-Hill approximation, in which the crystallographic textures and microstructures formed by the preparation processes were taken into account. The analyses revealed that the elastic properties of 18R-LPSO phase were not unique and they depended on the solute Zn and Y atom concentrations. Additionally, the elastic modulus of 18R-LPSO phase embedded in the two-phase alloy was lower than that of the alloy consisting of single-phase 18R-LPSO phase. The analysis using first-principles calculations based on density functional theory indicated that the low elastic modulus was caused by low density and low stability of short-range ordered solute atom clusters embedded in the LPSO phase of the two-phase alloy. Because of low elastic modulus in the LPSO phase, the elastic mismatch and resultant elastic interaction between the α-Mg and LPSO phases were very small. As a result, the formation of LPSO phase had little effect on the stress partitioning to the LPSO phase, which was independent of the LPSO-phase morphology.