中文摘要：

为进一步了解SiC材料力学性能机理，采用Tersoff势对SiC在不同温度下初裂纹前缘沿[100]、[110]、[111]个不同晶向的裂纹扩展进行了分子动力学模拟．裂纹前缘方向为[100]、[111]晶向的初裂纹扩展模拟结果表明：裂纹扩展方式为脆性解理断裂，低应力下裂纹尖端表面有无序带形成，在保证裂纹张开力作用下，裂纹尖端存在尖锐-钝化-尖锐的扩展过程．裂纹前缘方向为[110]晶向的初裂纹扩展模拟结果表明：裂纹出现明显“取向效应”，裂纹传播方向脱离了原有晶向（约60度）而选择沿其它晶向传播，裂纹扩展比较容易，裂纹断裂面几乎是完美的平面．

英文摘要：

Through molecular dynamics method with Tersoff potential, the propagation of the cracks is studied in SiC under different temperatures, with the initial crack front directions along [100], [110] and [111], respectively. The results showed that, it propagated by the mode of cleavage fracture ,at low tension. For the crack with [100] or [111] being the crack front, at low tension, a disordered band formed at the crack tip, while under the tension that could guarantee the crack to open, a sharpness-bluntness-sharpness propagation process at the crack tip. It is easy for the crack with [110] direction to propagate, and during the propagation ＂orientation effect＂ gradually appeared with about 60 degrees departure from the initial direction. The surface of crack was almost plane.