Influence of point defects on grain boundary mobility in bcc tungsten
Influence of point defects on grain boundary mobility in bcc tungsten
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DOI：
10.1088/0953-8984/25/3/035402
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发表时间：
2013-01-23
影响因子：
2.7
通讯作者：
Voter, Arthur F.
中科院分区：
文献类型：
--
作者：
Borovikov, Valery;Tang, Xian-Zhu;Voter, Arthur F.
采用原子计算机模拟研究了辐射损伤对bcc钨(W)晶界滑动过程的影响。bcc钨是ITER托卡马克的转移材料，也是未来聚变反应堆第一壁材的主要候选材料。特别地，我们计算了平均滑动摩擦力作为引入到对称倾斜GB的点缺陷数量的函数。在所有情况下，固定剪切应变率下的平均滑动摩擦力取决于引入点缺陷的数量，在许多情况下，这些缺陷的引入使平均滑动摩擦力减少了大约一个数量级。我们还观察到，随着GB中间隙数量的变化，耦合GB运动的方向有时会逆转，导致GB在相同的施加剪切应力下向相反方向迁移。这对于多晶钨在核聚变反应堆恶劣辐射环境下的微观结构演变可能是重要的，在这种环境下，高内应力存在，频繁的碰撞级联产生间隙和空位。
Atomistic computer simulations were performed to study the influence of radiation-induced damage on grain boundary (GB) sliding processes in bcc tungsten (W), the divertor material in the ITER tokamak and the leading candidate for the first wall material in future fusion reactors. In particular, we calculated the average sliding-friction force as a function of the number of point defects introduced into the GB for a number of symmetric tilt GBs. In all cases the average sliding-friction force at fixed shear strain rate depends on the number of point defects introduced into the GB, and in many cases introduction of these defects reduces the average sliding-friction force by roughly an order of magnitude. We have also observed that as the number of interstitials in the GB is varied, the direction of the coupled GB motion sometimes reverses, causing the GB to migrate in the opposite direction under the same applied shear stress. This could be important in the microstructural evolution of polycrystalline W under the harsh radiation environment in a fusion reactor, in which high internal stresses are present and frequent collision cascades generate interstitials and vacancies.