Sha Z D, Branicio P S, Pei Q X, Liu Z S, Lee H P, Tay T E, Wang T J
International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an 710049, China.
Nanoscale. 2015 Nov 7;7(41):17404-9. doi: 10.1039/c5nr04740d.
The strength-ductility tradeoff has been a common long-standing dilemma in materials science. For example, superplasticity with a tradeoff in strength has been reported for Cu50Zr50 nanoglass (NG) with grain sizes below 5 nm. Here we report an improvement in strength without sacrificing superplasticity in Cu50Zr50 NG by using a bimodal grain size distribution. Our results reveal that large grains impart high strength, which is in striking contrast to the physical origin of the improvement in strength reported in the traditional nanostructured metals/alloys. Furthermore, the mechanical properties of NG with a bimodal nanostructure depend critically upon the fraction of large grains. By increasing the fraction of the large grains, a transition from superplastic flow to failure by shear banding is clearly observed. We expect that these results will be useful in the development of a novel strong and superplastic NG.
强度与延展性之间的权衡一直是材料科学中一个长期存在的常见难题。例如，据报道，晶粒尺寸小于5纳米的Cu50Zr50纳米玻璃（NG）具有强度权衡的超塑性。在此，我们报告通过使用双峰晶粒尺寸分布，在不牺牲Cu50Zr50 NG超塑性的情况下提高了强度。我们的结果表明，大晶粒赋予了高强度，这与传统纳米结构金属/合金中报道的强度提高的物理起源形成了鲜明对比。此外，具有双峰纳米结构的NG的力学性能严重依赖于大晶粒的比例。通过增加大晶粒的比例，可以清楚地观察到从超塑性流动到剪切带破坏的转变。我们期望这些结果将有助于新型高强度和超塑性NG的开发。
