Chen Mingwei, Inoue Akihisa, Zhang Wei, Sakurai Toshio
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
Phys Rev Lett. 2006 Jun 23;96(24):245502. doi: 10.1103/PhysRevLett.96.245502. Epub 2006 Jun 21.
Shear bands generally initiate strain softening and result in low ductility of metallic glasses. In this Letter, we report high-resolution electron microscope observations of shear bands in a ductile metallic glass. Strain softening caused by localized shearing was found to be effectively prevented by nanocrystallization that is in situ produced by plastic flow within the shear bands, leading to large plasticity and strain hardening. These atomic-scale observations not only well explain the extraordinary plasticity that was recently observed in some bulk metallic glasses, but also reveal a novel deformation mechanism that can effectively improve the ductility of monolithic metallic glasses.
剪切带通常会引发应变软化，并导致金属玻璃的延展性较低。在本信函中，我们报告了对一种延性金属玻璃中剪切带的高分辨率电子显微镜观察结果。发现由局部剪切引起的应变软化可通过剪切带内塑性流动原位产生的纳米晶化得到有效抑制，从而实现大的塑性和应变硬化。这些原子尺度的观察结果不仅很好地解释了最近在一些块状金属玻璃中观察到的非凡塑性，还揭示了一种可有效提高整体金属玻璃延展性的新型变形机制。
