【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]三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.更多还原

【Abstract】 Through molecular dynamics method with Tersoff potential,the propagation of thecracks is studiedin SiC under different temperatures,with the initial crackfront directions along[100],[110] and [111],respectively.The results showed that,it propagated by the mode ofcleavage fracture,at lowtension.For the crack with [100] or [111] beingthe crackfront,at lowtension,a disordered band formed at the crack tip,while under the tension that could guaranteethe crack to open,a sharpness—bluntness—sharpness propagation process at the crack tip.It iseasy for the crack with [110] direction to propagate,and during the propagation“orientationeffect”gradually appeared with about 60 degrees departure fromtheinitial direction.The surfaceof crack was al most plane.更多还原