The role of heterogeneous deformation on damage nucleation at grain boundaries in single phase metals
The role of heterogeneous deformation on damage nucleation at grain boundaries in single phase metals
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DOI：
10.1016/j.ijplas.2008.09.002
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发表时间：
2009-09-01
影响因子：
9.8
通讯作者：
Raabe, D.
中科院分区：
文献类型：
--
作者：
Bieler, T. R.;Eisenlohr, P.;Raabe, D.
通过连续断裂力学评估的工程材料的机械响应通常假设裂纹或空隙最初存在，但它不提供有关在其他无缺陷的微观结构中的此类缺陷的成核的信息。这种缺陷是如何产生的，特别是在晶粒（或相）边界处，尚不清楚。实验上，“好”与“坏”晶界经常被援引为临界损伤成核的原因，但没有任何量化。在或附近的晶界，包括滑移转移和非均匀变形变形的变形的知识状态，进行审查，以表明很少的工作已经做了研究如何滑移相互作用可以导致损伤成核。最近开发的断裂起始参数的低延性模型材料与限滑系统提供了一个新的定义的晶界特征的基础上操作滑移和孪生系统（而不是界面能为基础的定义）。这提供了一种在物理和局部（而不是统计）基础上预测损伤成核密度的方法。该参数评估的方式，高度激活的双系统对齐的主应力和滑移系统伯格斯矢量。一个晶体塑性有限元法（CP-FEM）为基础的模型的一个广泛特征的微观结构区域已被用来确定应力-应变的历史提供任何额外的见解之间的关系剪切和损伤成核。分析表明，CP-FEM模型与断裂起始参数的组合显示出成为识别易损坏边界的预测工具的希望。(C)2008爱思唯尔有限公司保留所有权利。
The mechanical response of engineering materials evaluated through continuum fracture mechanics typically assumes that a crack or void initially exists, but it does not provide information about the nucleation of such flaws in an otherwise flawless microstructure. How such flaws originate, particularly at grain (or phase) boundaries is less clear. Experimentally, "good" vs. "bad" grain boundaries are often invoked as the reasons for critical damage nucleation, but without any quantification. The state of knowledge about deformation at or near grain boundaries, including slip transfer and heterogeneous deformation, is reviewed to show that little work has been done to examine how slip interactions can lead to damage nucleation. A fracture initiation parameter developed recently for a low ductility model material with limited slip systems provides a new definition of grain boundary character based upon operating slip and twin systems (rather than an interfacial energy based definition). This provides a way to predict damage nucleation density on a physical and local (rather than a statistical) basis. The parameter assesses the way that highly activated twin systems are aligned with principal stresses and slip system Burgers vectors. A crystal plasticity-finite element method (CP-FEM) based model of an extensively characterized microstructural region has been used to determine if the stress-strain history provides any additional insights about the relationship between shear and damage nucleation. This analysis shows that a combination of a CP-FEM model augmented with the fracture initiation parameter shows promise for becoming a predictive tool for identifying damage-prone boundaries. (C) 2008 Elsevier Ltd. All rights reserved.