Deformation and Void Structure in Glass

摘要

Network and void structures were investigated by a molecular dynamics simulation and a volume rendering method for glasses in the system of Na_20-Al_2O_3-SiO_2, to clarify inelastic deformation mechanism under stress before fracture. Glass had larger and more voids, as Na-content decreased. Under tension, the voids in SiO_2 glass expanded by breaking network rings with increasing strain, but the voids in Na_20-SiO_2 glass changed slightly by rearranging network rings. Under compression, as Na-content decreased, glass showed greater densification by crushing larger voids with increasing strain, but the void structures after the densification became quite similar, irrespective of Na-content. The substitution of Al ion for Si ion in Na_2O-SiO_2 glasses resulted in easier breakage of network ring without void formation during inelastic deformation, although the substitution leads to higher elastic moduli.