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Achieving High Strength and Ductility in Magnesium Alloys via Densely Hierarchical Double Contraction Nanotwins
Nano Letters ( IF 10.8 ) Pub Date : 2017-09-05 00:00:00 , DOI: 10.1021/acs.nanolett.7b02641
Hui Fu 1 , Bincheng Ge 1 , Yunchang Xin 2 , Ruizhi Wu 3 , Carlos Fernandez 4 , Jianyu Huang 1 , Qiuming Peng 1
Affiliation  

Light-weight magnesium alloys with high strength are especially desirable for the applications in transportation, aerospace, electronic components, and implants owing to their high stiffness, abundant raw materials, and environmental friendliness. Unfortunately, conventional strengthening methods mainly involve the formation of internal defects, in which particles and grain boundaries prohibit dislocation motion as well as compromise ductility invariably. Herein, we report a novel strategy for simultaneously achieving high specific yield strength (∼160 kN m kg–1) and good elongation (∼23.6%) in a duplex magnesium alloy containing 8 wt % lithium at room temperature, based on the introduction of densely hierarchical {101̅1}–{101̅1} double contraction nanotwins (DCTWs) and full-coherent hexagonal close-packed (hcp) particles in twin boundaries by ultrahigh pressure technique. These hierarchical nanoscaled DCTWs with stable interface characteristics not only bestow a large fraction of twin interface but also form interlaced continuous grids, hindering possible dislocation motions. Meanwhile, orderly aggregated particles offer supplemental pinning effect for overcoming latent softening roles of twin interface movement and detwinning process. The processes lead to a concomitant but unusual situation where double contraction twinning strengthens rather than weakens magnesium alloys. Those cutting-edge results provide underlying insights toward designing alternative and more innovative hcp-type structural materials with superior mechanical properties.

中文翻译:

通过密集分层双收缩纳米孪晶在镁合金中实现高强度和延展性

具有高强度的轻质镁合金由于其高刚度,丰富的原材料和环境友好性,特别适用于运输,航空航天,电子元件和植入物。不幸的是,常规的加固方法主要涉及内部缺陷的形成,其中颗粒和晶界阻止位错运动并始终损害延展性。本文中,我们报告了一种同时实现高比屈服强度(〜160 kN m kg –1的新颖策略)的方法。),并且在室温下,由于引入了密集的{101̅1} – {101̅1}双收缩纳米孪晶(DCTWs)和全相干六角形密闭合金,在含8 wt%锂的双相镁合金中具有良好的伸长率(〜23.6%)。通过超高压技术将颗粒(hcp)堆积在两个边界中。这些具有稳定界面特性的分层纳米级DCTWs不仅赋予了很大一部分孪生界面,而且还形成了交错的连续网格,从而阻碍了可能的位错运动。同时,有序聚集的颗粒提供补充的钉扎效果,以克服双界面运动和解缠过程的潜在软化作用。该过程导致伴随但不寻常的情况,即双收缩孪晶会增强而不是削弱镁合金。
更新日期:2017-09-06
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