Experimentally quantifying critical stresses associated with basal slip and twinning in magnesium using micropillars
Experimentally quantifying critical stresses associated with basal slip and twinning in magnesium using micropillars
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DOI：
10.1016/j.actamat.2017.06.008
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发表时间：
2017-08-15
期刊：
影响因子：
9.4
通讯作者：
Tome, C. N.
中科院分区：
文献类型：
--
作者：
Liu, Y.;Li, N.;Tome, C. N.
密排六方镁合金的塑性变形机制主要有基底滑移和（01（1）over bar 2）孪晶。在这里，我们量化的临界应力与基滑移和孪生单晶和双晶镁样品进行原位压缩的微柱在扫描电子显微镜中具有不同的直径。微柱被设计成在单轴压缩下有利于滑移或孪生。压缩试验意味着可以忽略不计的尺寸效应有关的基础滑移和孪生支柱直径大于10 μ m。通过一系列的微柱压缩试验，推导出孪晶的临界剪切应力为29 MPa，基底滑移的临界剪切应力为6 MPa。采用全场弹粘塑性模拟，我们进一步解释了实验观察的局部应力分布与多重孪生，孪生成核，和孪生生长。我们的模拟结果表明，所研究的孪晶特征不应该接近微柱的顶面，因为硬压头引起的局部应力扰动。由爱思唯尔有限公司代表Acta Materialia Inc.出版。
Basal slip and (01 (1) over bar2) twinning are two major plastic deformation mechanisms in hexagonal closed packed magnesium. Here we quantify the critical stresses associated with basal slip and twinning in single-crystal and bi-crystal magnesium samples by performing in situ compression of micropillars with different diameters in a scanning electron microscope. The micropillars are designed to favor either slip or twinning under uniaxial compression. Compression tests imply a negligible size effect related to basal slip and twinning as pillar diameter is greater than 10 mu m. The critical resolved shear stresses are deduced to be 29 MPa for twinning and 6 MPa for basal slip from a series of micropillar compression tests. Employing full-field elasto-visco-plastic simulations, we further interpret the experimental observations in terms of the local stress distribution associated with multiple twinning, twin nucleation, and twin growth. Our simulation results suggest that the twinning features being studied should not be close to the top surface of the micropillar because of local stress perturbations induced by the hard indenter. Published by Elsevier Ltd on behalf of Acta Materialia Inc.