Influence of spinodal decomposition structures on the strength of Fe-Cr alloys: A dislocation dynamics study
Influence of spinodal decomposition structures on the strength of Fe-Cr alloys: A dislocation dynamics study
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DOI：
10.1016/j.actamat.2017.12.051
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发表时间：
2018-03
期刊：
影响因子：
9.4
通讯作者：
A. Takahashi;T. Suzuki;A. Nomoto;T. Kumagai
中科院分区：
文献类型：
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作者：
A. Takahashi;T. Suzuki;A. Nomoto;T. Kumagai
本文采用位错动力学（DD）方法，对旋多分解对Fe-Cr合金强度的影响进行了数值分析。在DD模拟中，独立分解的铬分布的结构是用余弦函数近似的。利用内应力分布方程，精确地解释了位错与内应力分布之间的相互作用。利用铬浓度的大小、铬分布的波长、位错滑移面位置和位错特征（位错线与Burgers矢量之间的夹角）四个变量参数化了独立分解铬分布的结构。利用这些变量，研究了铬的分布结构对临界分解剪应力（CRSS）的影响。在此基础上，以{110}< 111>和{112}< 111>两个BCC构造的主要滑动体系为研究对象，讨论了不同滑动体系对BCC构造的影响差异。在{110}< 111>滑移体系中，由于分解剪应力分布呈条形分布，Δ CRSS只出现在θ= 54.7°的混合位错处。另一方面，在{112}< 111>滑移体系中，θ= 39.2°和90°的位错具有较大的Δ CRSS。在39.2°< θ< 90°范围内，有Δ的稳定度。滑移面位置不改变Δ CRSS。Δ CRSS与铬分布的波长有关。通过DD模拟可以发现Δ CRSS对波长的依赖性与直线位错无关，而与弯曲位错有关。这是一个新发现，对理解材料强度与旋多分解结构之间的关系具有重要意义。
This paper presents a numerical analysis of the influence of spinodal decomposition on the strength of Fe-Cr alloys using the dislocation dynamics (DD) method. In the DD simulations, the structure of a spinodally decomposed chromium distribution is approximated using a cosine function. Using the equation for internal stress distribution, the interaction between a dislocation and the internal stress distribution is precisely accounted for in the DD simulations. The structure of the spinodally decomposed chromium distribution is parameterized using four variables, including the magnitude of chromium concentration, wave length of chromium distribution, position of the slip plane of dislocation, and the dislocation character (angle between the dislocation line and Burgers vector). Using these variables, the influence of the structure of chromium distribution on the critical resolved shear stress (CRSS) is studied. Furthermore, we focused on two major slip systems of the BCC structure,{110}< 111> and {112}< 111>, and discuss the difference in the influence between the different slip systems. In the {110}< 111> slip system, the Δ CRSS appears only for a mixed dislocation with θ= 54.7°, because of the stripe pattern of the resolved shear stress distribution. On the other hand, in the {112}< 111> slip system, the dislocations with θ= 39.2° and 90° have a large Δ CRSS. There is a plateau of Δ CRSS in a range of 39.2∘< θ< 90∘. The slip plane position does not change the Δ CRSS. There is a dependence of Δ CRSS on the wave-length of the chromium distribution. The dependence of Δ CRSS on the wave-length can be found not with a straight dislocation but with a curved dislocation using the DD simulations. The information is a new finding, and is meaningful in understanding the relationship between the material strength and the structure of spinodal decomposition.