A Transforming Metal Nanocomposite with Large Elastic Strain, Low Modulus, and High Strength
A Transforming Metal Nanocomposite with Large Elastic Strain, Low Modulus, and High Strength
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一种大弹性应变、低模量、高强度的相变金属纳米复合材料
DOI：
10.1126/science.1228602
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发表时间：
2013-03-08
期刊：
影响因子：
56.9
通讯作者：
Li, Ju
中科院分区：
文献类型：
--
作者：
Hao, Shijie;Cui, Lishan;Li, Ju
大多数金属的弹性应变极限远低于1%，超过这个极限就会发生永久塑性变形。金属纳米线可以弹性拉伸到更高的应变，大约4至7%。然而，当放置在金属基质内形成复合材料时，这些纳米线不再能被拉伸到相同的程度，即使纳米线分布良好并与基质表现出良好的结合。Hao等人（第1191页;参见Zhou的Perspective）使用形状记忆合金作为基质材料，以生产更好（更有弹性）的复合材料。使用形状记忆金属合金作为基质更好地利用了铌纳米线的固有弹性。[Also独立的纳米线具有弹性应变极限（4 - 7%）和屈服强度，但是在块状复合材料中利用其固有的机械性能已被证明是困难的。基于弹性和相变应变匹配的概念，我们利用了相变基质中纳米线的固有力学性质。通过工程的微观结构和残余应力耦合铌纳米线的真实弹性与伪弹性的镍钛形状记忆合金，我们开发了一种原位复合材料，具有一个大的准线性弹性应变超过6%，低杨氏模量约28吉帕斯卡，和高屈服强度约1.65吉帕斯卡。我们的弹性应变匹配方法允许在体材料中利用纳米线的特殊机械性能。
S-T-R-E-T-C-H Me Most metals show elastic strain limits well below 1%, beyond which permanent plastic deformation occurs. Metal nanowires can be elastically stretched to much higher strains, on the order of 4 to 7%. However, when placed inside a metal matrix to form a composite, these nanowires can no longer be stretched to the same extent, even when the nanowires are well distributed and show good bonding with the matrix. Hao et al. (p. 1191; see the Perspective by Zhou) used a shape memory alloy as the matrix material to produce a much better (more elastic) composite. The use of a shape-memory metal alloy as a matrix better exploits the inherent elastic properties of niobium nanowires. [Also see Perspective by Zhou] Freestanding nanowires have ultrahigh elastic strain limits (4 to 7%) and yield strengths, but exploiting their intrinsic mechanical properties in bulk composites has proven to be difficult. We exploited the intrinsic mechanical properties of nanowires in a phase-transforming matrix based on the concept of elastic and transformation strain matching. By engineering the microstructure and residual stress to couple the true elasticity of Nb nanowires with the pseudoelasticity of a NiTi shape-memory alloy, we developed an in situ composite that possesses a large quasi-linear elastic strain of over 6%, a low Young's modulus of ~28 gigapascals, and a high yield strength of ~1.65 gigapascals. Our elastic strain-matching approach allows the exceptional mechanical properties of nanowires to be exploited in bulk materials.