Effects of temperature and strain rate on dynamic crack propagation in brittle silicon

Abstract

Based on molecular dynamics, this study investigates the brittle fracture of silicon as a function of temperature and strain rate from an atomic perspective. The fracture toughness increases with increasing temperature, whereas the opposite trend is observed at a higher strain rate. When the critical state is reached, the atomic structures and stress concentration at the sharp crack tip determine crack path selection. The (111)[11̅0] crack system propagates in a straight line owing to the sequential breaking of only the maximum stressed bond directly in front of the crack. By contrast, the (110)[1̅10] crack system propagates in a straight line or is deflected among different cleavage planes owing to the breaking of two highly stressed bridging bonds. In addition, the corresponding velocity of the crack tip may be affected by these two factors; essentially, it increases at higher temperatures and strain rates.