Modeling analysis of the influence of plasticity on high pressure deformation of hcp-Co
Modeling analysis of the influence of plasticity on high pressure deformation of hcp-Co
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DOI：
10.1103/physrevb.79.064110
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发表时间：
2009-02
影响因子：
3.7
通讯作者：
S. Merkel;C. Tomé;H. Wenk
中科院分区：
文献类型：
--
作者：
S. Merkel;C. Tomé;H. Wenk
先前测量的原位X-射线衍射用于评估内部弹性应变内的晶粒的多晶钴的样品塑性变形高达42.6 GPa的压力的发展。采用弹塑性自洽多晶体模型模拟了试样的宏观流动曲线和内部应变发展。输入参数是单晶体的弹性模量和它们的压力依赖性，临界分解的剪切应力，和硬化行为的滑移和孪生机制，这是活跃在Co晶体。在42 GPa时，hcp-Co中的差应力为1.9\ifmmode\pm\else\textpm\fi {}0.1\text{ }\text{GPa}$。实验和预测数据之间的比较导致我们得出结论：（a）塑性弛豫起着主要的作用，在控制的演变和有序的晶格应变;（B）hcp-Co在高压下变形的塑性行为是由基底和棱柱滑移的$a $位错，或者金字塔滑移的$c+a $位错，或压缩孪生，或两者兼而有之。基底滑动是迄今为止最简单和最活跃的变形机制。弹塑性自洽模型示出，以克服基于连续弹性理论的模型的局限性，用于解释应力样品上测量的X射线衍射数据。它们应用于解释这些实验。
Previously measured in situ x-ray diffraction is used to assess the development of internal elastic strains within grains of a sample of polycrystalline cobalt plastically deformed up to a pressure of 42.6 GPa. An elastoplastic self-consistent polycrystal model is used to simulate the macroscopic flow curves and internal strain development within the sample. Input parameters are single-crystal elastic moduli and their pressure dependence, critical resolved shear stresses, and hardening behavior of the slip and twinning mechanisms which are active in Co crystals. At 42 GPa, the differential stress in hcp-Co is $1.9\ifmmode\pm\else\textpm\fi{}0.1\text{ }\text{GPa}$. The comparison between experimental and predicted data leads us to conclude that: (a) plastic relaxation plays a primary role in controlling the evolution and ordering of the lattice strains; (b) the plastic behavior of hcp-Co deforming under high pressure is controlled by basal and prismatic slip of $⟨a⟩$ dislocations, and either pyramidal slip of $⟨c+a⟩$ dislocations, or compressive twinning, or both. Basal slip is by far the easiest and most active deformation mechanism. Elastoplastic self-consistent models are shown to overcome the limitations of models based on continuum elasticity theory for the interpretation of x-ray diffraction data measured on stressed samples. They should be used for the interpretation of these experiments.