Molecular Dynamics Simulation of Edge Dislocation Piled at Cuboidal Precipitate in Ni-Based Superalloy.
Molecular Dynamics Simulation of Edge Dislocation Piled at Cuboidal Precipitate in Ni-Based Superalloy.
复制标题
镍基高温合金中立方形析出物堆积的刃位错的分子动力学模拟。
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
Y. Tomita
中科院分区：
文献类型：
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作者：
K. Yashiro;M. Naito;Y. Tomita
为了阐明镍基高温合金γ/γ'显微组织中位错的基本机制，对剪切力作用下从自由表面形核的刃位错在纯Ni基体(γ)中向立方体Ni3Al析出物(γ')的行为进行了三种分子动力学模拟。其中一种涉及两个相邻析出物顶点附近的位错，这两个析出物彼此相邻，距离为 0.04 μm，与实际高温合金中 γ 通道的宽度一样大。其他人也模拟了析出物处堆积的位错，然而，显微组织的规模比实际高温合金小一个数量级，并且其中一种析出物具有原子级锐利边缘。位错被钉扎在析出物上并在 γ 通道中弯曲，然后当析出物具有钝边缘时，它们开始在真实尺度和较小的微观结构中渗透到边缘处的析出物中。另一方面，刃位错分裂成γ'析出物中的超部分位错和在γ'析出物的原子尖锐边缘处桥接在两个相邻析出物之间的失配螺旋位错。还观察到两个超部分在沉淀物中作为具有反相边界（APB）的超位错滑动，其宽度估计为约4 nm。
In order to clarify the fundamental mechanism of dislocations in the γ/γ' microstructure of Ni-based superalloy, three molecular dynamics simulations are conducted on the behavior of edge dislocations nucleated from a free surface and proceeding in the pure Ni matrix (γ) toward cuboidal Ni3Al precipitates (γ') under shear force. One involves dislocations near the apices of two precipitates adjoining each other with the distance of 0.04 μm, as large as the width of the γ channel in real superalloys. Others simulate dislocations piled at the precipitates as well, however, the scale of the microstructure is smaller than that in real superalloys by one order of magnitude, and one of them have precipitates with atomistically sharp edge. Dislocations are pinned at precipitates and bowed-out in the γ channel, then they begin to penetrate into the precipitate at the edge in both the real-scale and smaller microstructures when the precipitates have blunt edges. On the other hand, an edge dislocation splits into a superpartial in the γ' precipitate and a misfit screw dislocation bridging between two adjacent precipitates at the atomistically sharp edge of γ' precipitates. It is also observed that two superpartials glide in the precipitate as a superdislocation with anti-phase boundary (APB), of which the width is evaluated to be about 4 nm.