Nanolaminates Utilizing Size-Dependent Homogeneous Plasticity of Metallic Glasses
Nanolaminates Utilizing Size-Dependent Homogeneous Plasticity of Metallic Glasses
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DOI：
10.1002/adfm.201101164
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发表时间：
2011-12-06
影响因子：
19
通讯作者：
Greer, Julia R.
中科院分区：
文献类型：
--
作者：
Kim, Ju-Young;Jang, Dongchan;Greer, Julia R.
金属玻璃中的均匀塑性通常只在高温或非常小的结构(小于100 nm)下才能观察到，因此它们在结构性能方面的应用一直非常有限。本文合成了Cu50Zr50金属玻璃和纳米晶铜交替层的纳米层状结构，发现当玻璃层厚度为112 nm，铜层厚度为16 nm时，其最大强度为2.513 Gpa，比按混合规则预测的强度提高了33%，比纯Cu50Zr50金属玻璃的强度提高了25%。此外，在断裂时获得了大约4%的应变，抑制了通常与金属玻璃相关的瞬时灾难性破坏。这种高强度和高变形性的良好组合是由于金属玻璃中与尺寸有关的变形模式从高度局域塑性转变到小样本的均匀扩展所致。
Homogeneous plasticity in metallic glasses is generally only observed at high temperatures or in very small structures (less than approximate to 100 nm), so their applications for structural performance have been very limited. Here, nanolaminates with alternating layers of Cu50Zr50 metallic glass and nanocrystalline Cu are synthesized and it is found that samples with an optimal composition of 112-nm-thick metallic-glass layers and 16-nm-thick Cu layers demonstrate a maximum strength of 2.513 GPa, a value 33% greater than that predicted by the rule-of-mixtures and 25% better than that of pure Cu50Zr50 metallic glass. Furthermore, approximate to 4% strain at fracture is achieved, suppressing the instantaneous catastrophic failure often associated with metallic glasses. It is postulated that this favorable combination of high strength and deformability is caused by the size-dependent deformation-mode transition in metallic glasses, from highly localized plasticity, leading to immediate failure in larger samples to homogeneous extension in the smaller ones.