Chen Yi-Chun, Nomura Ken-ichi, Kalia Rajiv K, Nakano Aiichiro, Vashishta Priya
Department of Physics and Astronomy, Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, California 90089-0242, USA.
Phys Rev Lett. 2009 Jul 17;103(3):035501. doi: 10.1103/PhysRevLett.103.035501. Epub 2009 Jul 16.
We study shear deformation and breakup of voids in silica glass using molecular dynamics simulations. With an increase in the shear strain, two kinds of defects--threefold-coordinated silicon and nonbridging oxygen atoms--appear as spherical voids deform elastically into ellipsoidal shapes. For shear strains epsilon>15%, nanocracks appear on void surfaces and voids deform plastically into a threadlike structure. Nanocracks are nucleated by the migration of threefold-coordinated Si and nonbridging O on -Si-O-Si-O- rings. For epsilon>40%, the threadlike structures break up into several fragments.
我们使用分子动力学模拟研究了石英玻璃中空洞的剪切变形和破裂。随着剪切应变的增加，当球形空洞弹性变形为椭圆形时，会出现两种缺陷——三配位硅和非桥连氧原子。当剪切应变ε>15%时，空洞表面会出现纳米裂纹，空洞会塑性变形为丝状结构。纳米裂纹是由三配位硅和非桥连氧在-Si-O-Si-O-环上的迁移而形成的。当ε>40%时，丝状结构会分裂成几个碎片。
