On plastic flow in notched hexagonal close packed single crystals
On plastic flow in notched hexagonal close packed single crystals
复制标题
DOI：
10.1016/j.jmps.2016.04.023
复制
发表时间：
2016-09
影响因子：
5.3
通讯作者：
Balaji Selvarajou;B. Kondori;A. Benzerga;S. Joshi
中科院分区：
文献类型：
--
作者：
Balaji Selvarajou;B. Kondori;A. Benzerga;S. Joshi
计算研究了单晶缺口试件中滑移和孪生联合作用下各向异性塑性流动的细观力学行为。文中采用了六方密排材料的本构关系，它考虑了弹性各向异性、30个势变形系统、各种硬化机制和速率敏感性。试件垂直于c轴加载，但缺口的存在会产生三维三轴应力状态。这项研究是由最近对一种多晶镁合金的实验推动的。为了能够在适当的情况下与这些进行比较，使用了用于各种变形系统的三组激活阈值。在最接近于合金材料的条件下，重点关注棱锥形和棱柱形滑移的相对作用，以及在足够高的三轴度下出现的{1012‘}[101’1]伸展孪晶。在所有情况下，包含各种系统活动的应力三轴性和塑性应变的空间变化以及它们在应变时的演化被量化。讨论了这些结果对基本理解HCP合金，特别是镁合金延性破坏的意义。
The micromechanics of anisotropic plastic flow by combined slip and twinning is investigated computationally in single crystal notched specimens. Constitutive relations for hexagonal close packed materials are used which take into account elastic anisotropy, thirty potential deformation systems, various hardening mechanisms and rate-sensitivity. The specimens are loaded perpendicular to the c-axis but the presence of a notch generates three-dimensional triaxial stress states. The study is motivated by recent experiments on a polycrystalline magnesium alloy. To enable comparisons with these where appropriate, three sets of activation thresholds for the various deformation systems are used. For the conditions that most closely mimic the alloy material, attention is focused on the relative roles of pyramidal< c+ a> and prismatic< a> slip, as well as on the emergence of {1012¯}[101¯ 1] extension twinning at sufficiently high triaxiality. In all cases, the spatial variations of stress triaxiality and plastic strain, inclusive of various system activities, are quantified along with their evolution upon straining. The implications of these findings in fundamental understanding of ductile failure of HCP alloys in general and Mg alloys in particular are discussed.