Ledge effects on dislocation emission from a crack tip : a first-principles study for silicon
Ledge effects on dislocation emission from a crack tip : a first-principles study for silicon
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裂纹尖端位错发射的壁架效应：硅的第一性原理研究
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
E. Kaxiras
中科院分区：
文献类型：
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作者：
Yu;Yuemin Sun;E. Kaxiras
最近的广泛努力，以了解材料的内在脆性或延展性集中在裂纹钝化机制使用佩尔斯应力的概念。到目前为止，裂纹扩展过程中新产生的壁架表面的影响要么被忽略，要么被包含在一些半经验近似中。使用硅作为一个典型的脆性固体，我们表明，与新创建的凸缘表面在裂纹尖端的能量可以从第一性原理计算。我们将这些结果纳入一个连续理论的临界载荷的裂纹通过假设一个渐逝力法的表面效应。我们的研究结果表明，包括表面凸缘效应可以改变临界载荷的值高达20%。
Extensive recent efforts to understand the intrinsic brittleness or ductility of materials have focused on crack-blunting mechanisms using the Peierls stress concept. So far, the effects due to newly created ledge surface during crack propagation have been either ignored or included within some semiempirical approximation. Using silicon as a prototypical brittle solid, we show that the energy associated with a newly created ledge surface at a crack tip can be obtained from first-principles calculations. We incorporate these results into a continuum theory of critical loading of cracks by assuming an evanescent force law for the surface effects. Our results indicate that inclusion of surface ledge effects can change the values of the critical load by up to 20%.