PRODUCTION BIAS AND VOID SWELLING IN THE TRANSIENT REGIME UNDER CASCADE DAMAGE CONDITIONS
PRODUCTION BIAS AND VOID SWELLING IN THE TRANSIENT REGIME UNDER CASCADE DAMAGE CONDITIONS
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DOI：
10.1080/01418619208248002
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发表时间：
1992-12-01
期刊：
影响因子：
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通讯作者：
FOREMAN, AJE
中科院分区：
文献类型：
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作者：
SINGH, BN;FOREMAN, AJE
碰撞级联的分子动力学（MD）研究已经牢固地建立，除了集群的空位，集群的自填隙原子（SIAs）的级联体积内形成的热尖峰阶段的级联。这些集群形成在一个隔离的方式，这样的空位丰富的核心是由SIA集群包围。在高于阶段V的温度下，空位从空位除尘器蒸发并扩散到介质中，而SIA团簇在甚至高于峰值溶胀温度的温度下保持热稳定。这种不对称的自由和移动的空位和SIAs的生产引起了生产偏差。一些空位蒸发的空位在周围的SIAs集团湮灭，其他逃逸到介质中。正是这种空缺的逃逸分数决定了生产偏差的强度。扩散计算已被执行，以估计这种逃逸分数的空位的大小。计算所需的叶栅参数由MD模拟实验获得。几乎80%的空位保留在一个20 keV的级联的空位丰富的核心被发现逃脱级联体积包含SIA集群。我们将此逃逸率作为介质中的有效空位产生率，计算了523 K下完全退火纯铜在中子辐照下SIA团簇、空位尺寸和膨胀的时间演化。计算的溶胀行为的一般趋势与实验结果一致。目前的计算提供了进一步的有效性和支持的概念生产偏差。
Molecular dynamics (MD) studies of collision cascades have firmly established that, in addition to clusters of vacancies, clusters of self-interstitial atoms (SIAs) are formed within the cascade volume during the thermal spike phase of a cascade. These clusters are formed in a segregated fashion such that the vacancy-rich core is surrounded by SIA clusters. At temperatures above stage V the vacancies evaporate from the vacancy duster and diffuse into the medium whereas the SIA clusters remain thermally stable at temperatures even above the peak swelling temperature. This asymmetry in the production of free and mobile vacancies and SIAs gives rise to a production bias.Some of the vacancies evaporating from the vacancy-rich core annihilate at the SIA clusters surrounding it and others escape into the medium. It is this escaping fraction of vacancies which determines the strength of the production bias. Diffusion calculations have been performed to estimate the magnitude of this escaping fraction of vacancies. The necessary cascade parameters for this calculation are obtained from MD simulation experiments. Almost 80% of vacancies retained in the vacancy-rich core of a 20 keV cascade are found to escape the cascade volume containing SIA clusters. We have taken this escape rate to be the effective vacancy production rate in the medium, and calculated the temporal evolution of SIA clusters, void size and swelling for fully annealed pure copper under neutron irradiation at 523 K. The general trends of the calculated swelling behaviour are found to be in agreement with experimental results. The present calculations provide further validity and support to the concept of production bias.