Pre-compression effect on microstructure evolution of extruded pure polycrystalline magnesium during reversed tension load
Pre-compression effect on microstructure evolution of extruded pure polycrystalline magnesium during reversed tension load
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DOI：
10.1016/j.matchar.2017.10.003
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发表时间：
2017-12
影响因子：
4.7
通讯作者：
D. Culbertson;Qin Yu;Jian Wang;Yanyao Jiang
中科院分区：
文献类型：
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作者：
D. Culbertson;Qin Yu;Jian Wang;Yanyao Jiang
研究了挤压态纯多晶镁在压缩和拉伸过程中的组织演变规律。将实心圆形狗骨形试样沿着挤压方向（艾德）分别压缩至-7.3%和-12.8%真实应变，然后沿着艾德拉伸至失效。电子背散射衍射（EBSD）被用来检查微观结构的演变，使用同伴标本卸载在多个点沿着变形曲线。沿艾德向沿着预压缩导致10 1 2的拉伸孪晶，其体积随着应变的增加而增加，直到在约-10.5%的真实应变下耗尽。预压缩试样的拉伸再加载导致低施密德因子孪生、去孪生和二次10 1 <$2拉伸孪生的组合。在-7.3%预压缩样本中，解孪晶比二次孪晶更显著，其中仅观察到一个二次孪晶变体。在-12.8%预压缩的样本中，10 1 '2二次孪生更为显着，其中观察到多达三种二次孪生变体。在初生孪晶完全退孪后，二次孪晶保留下来并以亚晶粒的形式出现。二次孪晶形成的残余亚晶可能是变形镁合金的强化机制之一。
The microstructure evolution of extruded pure polycrystalline magnesium under compression followed by subsequent tension in ambient air was investigated. Solid round dog-bone shaped specimens were compressed along the extrusion direction (ED) to− 7.3% and− 12.8% true strains, respectively, and then tensioned along the ED to failure. Electron backscatter diffraction (EBSD) was used to examine the microstructure evolution using companion specimens unloaded at multiple points along the deformation curves. Pre-compression along the ED resulted in 10 1¯ 2 tension twinning which increased in volume with increasing strain until exhaustion at approximately− 10.5% true strain. Tensile reloading of the pre-compressed specimens led to a combination of low Schmid factor twinning, detwinning, and secondary 10 1¯ 2 tension twinning. Detwinning was more significant than secondary twinning in the− 7.3% pre-compressed specimens, where only one secondary twin variant was observed. 10 1¯ 2 secondary twinning was more significant in the− 12.8% pre-compressed specimens, where up to three secondary twin variants were observed. After complete detwinning of primary twins, the secondary twins were retained and appeared as sub-grains. The residual sub-grains resulted from secondary twinning may provide a strengthening mechanism for wrought Mg alloys.