Toughening magnesium with gradient twin meshes
Toughening magnesium with gradient twin meshes
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DOI：
10.1016/j.actamat.2020.05.021
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发表时间：
2020-05
期刊：
影响因子：
9.4
通讯作者：
Xin Wang;Lin Jiang;Chase Cooper;Kehang Yu;Dalong Zhang;T. Rupert;S. Mahajan;I. Beyerlein;E. Lavernia;J. Schoenung
中科院分区：
文献类型：
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作者：
Xin Wang;Lin Jiang;Chase Cooper;Kehang Yu;Dalong Zhang;T. Rupert;S. Mahajan;I. Beyerlein;E. Lavernia;J. Schoenung
在本研究中，我们结合联合收割机全面的网站特定的微观结构和机械特性的研究，以评估应用表面DAC铣削（SSM）的方法，以商业纯镁诱导的增韧效果。研究结果表明，自组织形变引起的高频、多向形变应变使晶粒尺寸和取向随深度的变化产生梯度。更重要的是，它还导致了孪晶网格密度的梯度，孪晶网格定义为沿着沿着样品厚度方向的两个或更多个相交的孪晶阵列。室温拉伸试验表明，经过SSM处理后，试样的极限抗拉强度比未处理的试样提高了一倍，延展性提高了一倍。利用电子背散射衍射（EBSD）分析了初始织构和SSM参数对织构演化和织构随机化的影响。此外，为了关联的微观结构的变化与特定部位的机械响应，TEM和在SEM中的in-situmicropillar压缩测试进行了各种距离的SSM处理的表面。结果表明，孪晶网格激活了更多的滑移系和更高的应变硬化，从而导致更高的均匀塑性应变。
In the present study, we combine comprehensive site-specific microstructural and mechanical characterization studies to evaluate the toughening effect induced by applying a surface SPEX milling (SSM) approach to commercially-pure Mg. Our results show that the high frequency, multi-directional deformation strain induced by SSM generated gradients in the grain size and orientation with depth from the surface. More importantly, it also resulted in a gradient in the density of twin meshes, which are defined as two or more intersecting arrays of twins, along the sample thickness direction. Tensile tests at room temperature indicate that after SSM, the samples have higher ultimate tensile strengths and two-fold increases in ductility as compared to those of the untreated samples. The effect of the initial texture and SSM parameters on the microstructural evolution and texture randomization were analyzed by electron backscattered diffraction (EBSD). Furthermore, in order to correlate the variation in microstructure with the site-specific mechanical response, TEM andin-situmicropillar compression testing in SEM were performed at various distances from the SSM-treated surface. The results show that twin meshes may be responsible for the activation of more slip systems and higher strain hardening, which result in higher uniform plastic strain.