Radiation resistance of nano-crystalline iron: Coupling of the fundamental segregation process and the annihilation of interstitials and vacancies near the grain boundaries
Radiation resistance of nano-crystalline iron: Coupling of the fundamental segregation process and the annihilation of interstitials and vacancies near the grain boundaries
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纳米晶铁的抗辐射性：基本偏析过程与晶界附近填隙和空位湮灭的耦合
DOI：
10.1016/j.actamat.2016.02.028
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发表时间：
2016-05-01
期刊：
影响因子：
9.4
通讯作者：
Wang, Zhiguang
中科院分区：
文献类型：
--
作者：
Li, Xiangyan;Liu, Wei;Wang, Zhiguang
寻找具有高抗辐射能力的新型核材料对于核工业非常重要，需要了解纳米晶铁等新型材料的辐射损伤自愈能力。结合分子动力学模拟、分子静力学计算和物体动力学蒙特卡罗方法，我们发现纳米晶铁的自修复能力与晶界（GB）附近空位和填隙的个体基本偏析和湮灭过程的耦合密切相关。静态地，在晶界附近和晶界处，间隙周围形成低能垒/无垒区域，这促进了空位的消灭。人们发现，由于间隙周围应变原子的恢复，湮灭过程总是涉及多个原子的集体运动。从动态上讲，湮灭涉及两个耦合过程。在分离到晶界之前，间隙原子随着低势垒区域一起在晶界附近扩散，消灭了晶界附近的大量空位。此外，尽管间隙原子在偏析后与晶界紧密结合，但它在沿着晶界移动的同时有效地去除了晶界附近的空位，低势垒区域延伸到晶界附近，甚至进入晶粒内部。人们发现这两种机制可以在低温下工作，甚至在空位不动的温度下也能工作。这项研究揭示了不同尺度下主要辐射缺陷的相互作用，从而揭示了纳米晶铁高抗辐射性的根源。 (C) 2016 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
Finding novel nuclear materials with high radiation resistance is very important for the nuclear industry and requires the understanding of the self-healing of radiation damage in such novel materials as nano crystalline iron. Combining molecular dynamics simulations, molecular statics calculations and the object kinetic Monte Carlo method, we found that the self-healing capability of nano-crystalline iron is closely related to the coupling of the individual fundamental segregation and annihilation processes of vacancies and interstitials near the grain boundary (GB). Statically, both near the GB and at the GB, a low-energy-barrier/barrier-free region forms around the interstitial which promotes the annihilation of vacancies. The annihilation process was found to always involve the collective motion of multiple atoms due to the recovery of the strained atoms around the interstitial. Dynamically, the annihilation involves two coupled processes. Before segregating into the GB, the interstitial annihilates lots of vacancies near the GB as it diffuses near the GB together with the low-barrier region. In addition, although the interstitial is tightly bound to the GB after segregation, it efficiently removes the vacancies near the GB while moving along the GB, with the low-barrier region extending into the neighborhood of the GB and even into the grain interior. These two mechanisms were found to work at low temperatures, even temperatures where the vacancy was immobile. This study revealed the interaction of the major radiation defects at different scales and thereby uncovered the origin of the high radiation resistance of nano crystalline iron. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.