In situ X-ray diffraction and crystal plasticity modeling of the deformation behavior of extruded Mg–Li–(Al) alloys: An uncommon tension–compression asymmetry
In situ X-ray diffraction and crystal plasticity modeling of the deformation behavior of extruded Mg–Li–(Al) alloys: An uncommon tension–compression asymmetry
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DOI：
10.1016/j.actamat.2014.12.003
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发表时间：
2015-03
期刊：
影响因子：
9.4
通讯作者：
M. Lentz;M. Klaus;I. Beyerlein;Milovan Zecevic;W. Reimers;M. Knezevic
中科院分区：
文献类型：
--
作者：
M. Lentz;M. Klaus;I. Beyerlein;Milovan Zecevic;W. Reimers;M. Knezevic
研究了合金添加量和晶粒尺寸对两种挤压态Mg-4 wt.% Li和Mg-4重量% Li-1重量%研究了铝合金。为了确定潜在的变形机制，我们采用了相结合的织构分析，在原位能量色散X射线同步辐射衍射和弹塑性自洽建模。我们发现，这两种合金表现出两个不寻常的功能：（1）低拉伸-压缩屈服强度的不对称性和（2）所谓的正不对称性，其中压缩屈服强度高于拉伸屈服强度。我们的分析表明，这种不寻常的不对称性的出现，因为添加锂阻碍激活{10 1>张力孪生。我们还表明，屈服应力和硬化速率的增加与Al的加入是一个结果，增加的阻力滑动，但在{10 1 <$2}< 10 1 <$1 <$>孪生阻力下降。
The effects of alloying additions and grain size on the deformation behavior of two extruded Mg–4 wt.% Li and Mg–4 wt.% Li–1 wt.% Al alloys were studied. To determine the underlying deformation mechanisms, we employed a combination of texture analysis, in situ energy dispersive X-ray synchrotron diffraction and elasto-plastic self-consistent modeling. We show that both alloys exhibit two uncommon features:(1) low tension–compression asymmetry in yield strength and (2) a so-called positive asymmetry in which the compression yield strength is higher than the tension yield strength. Our analyses suggest that this unusual asymmetry arises because the addition of Li hinders the activation of {10 1¯ 2}< 10 1¯ 1¯> tension twinning. We also show that the increases in the yield stress and hardening rate with the addition of Al is a consequence of increases in the resistances to slip but a decrease in the resistance to {10 1¯ 2}< 10 1¯ 1¯> twinning.