一直以来，如何评价非晶合金的塑性是一个重要问题。对于不同尺寸的非晶合金，塑性变形能力究竟如何呢？对此，作者进行了实验以及理论分析。

随着直径的减小，非晶合金试样产生破坏前所体现的塑性应变呈指数增加，强度则不断减小，这表明所研究的非晶态金属具有“愈小亦愈软”的趋势。对于具有相同化学成分的玻璃态合金而言，试样尺寸愈小，试样在凝固过程中所经历的冷却速度则越大，单位原子体积内自由体积的数量愈大，合金体内包含更多的具有高自由体积数量的区域，进而，促使剪切带的形核点愈多，导致合金在塑性变形过程中产生数量更多的剪切带，合金所体现的塑性更为优异。这说明试样尺寸在非晶态金属合金的塑性变形中占有至关重要的作用。

该结果发表在Applied Physics Letters （2007, 90: 081919）上,摘要信息如下：

Title：Bulk metallic glasses: Smaller is softer

Authors：Y.J. Huang, J. Shen, J.F. Sun

Abstract: The authors report on the dramatic effect of sample size on the plastic deformation capability of a Ti-based bulk metallic glass. Compared with the larger one, the smaller size glassy alloy with the same chemical composition exhibits significantly enhanced plasticity, suggesting a “smaller is softer” trend of metallic glasses. The phenomenon is attributed to the fact that the smaller size alloy, which experienced a faster cooling rate during solidification, contains a larger amount of heats of relaxation and crystallization, favoring the preferential nucleation of shear bands and thus allowing enhanced plasticity upon compressive loading.

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Bulk metallic glass: Smaller is softer

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