Nanocrystallization During Nanoindentation of a Bulk Amorphous Metal Alloy at Room Temperature
Nanocrystallization During Nanoindentation of a Bulk Amorphous Metal Alloy at Room Temperature
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DOI：
10.1126/science.1067453
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发表时间：
2002-01
期刊：
影响因子：
56.9
通讯作者：
J.-J. Kim-J.;Y. Choi;S. Suresh;A. Argon
中科院分区：
文献类型：
--
作者：
J.-J. Kim-J.;Y. Choi;S. Suresh;A. Argon
众所周知，在金属玻璃薄带的剧烈弯曲或高能球磨过程中产生的剪切带内能够形成纳米微晶。我们提供了直接的实验证据，表明在室温下对块状玻璃态金属合金进行准静态纳米压痕这种超细尺度的高度受限且可控的局部接触也能导致纳米晶化。原子力显微镜和透射电子显微镜显示，纳米微晶在压痕附近产生的剪切带内部及其周围成核，并且它们与在783开尔文无变形退火过程中形成的微晶相同。与近期对玻璃态聚合物的实验结果类似，我们的结果被认为是剪切带内部的流动膨胀以及在主动变形的剪切带内随之而来的、大幅增强的原子扩散迁移率的结果。
It is known that nanocrystallites can form in shear bands produced during severe bending or high-energy ball milling of thin ribbons of a metallic glass. We present direct experimental evidence that highly confined and controlled local contact at the ultrafine scale in the form of quasi-static nanoindentation of a bulk glassy metal alloy at room temperature can also cause nanocrystallization. Atomic force microscopy and transmission electron microscopy show that nanocrystallites nucleate in and around shear bands produced near indents and that they are the same as crystallites formed during annealing without deformation at 783 kelvin. Analogous to results from recent experiments with glassy polymers, our results are reasoned to be a consequence of flow dilatation inside the bands and of the attendant, radically enhanced, atomic diffusional mobility inside actively deforming shear bands.