High Resolution Electron-Microscope Study of Damage Evolution Processes in Metals and Their Alloys Irradiated with High Energy Particles

在本工作中，我们开发了低温辐照离子和中子的电子显微镜冷冻转移技术。从低温离子、裂变中子和聚变中子辐照金属的低温转移透射电镜实验结果来看，高能粒子辐照金属损伤级联的形成和演化过程如下：(1)当金属中产生初级碰撞原子时，它在与其他晶格原子碰撞后停止，形成位移损伤级联，其中心部分被高浓度的空位占据，并被间隙地幔包围。以前，人们认为空位聚集形成TEM可见簇（即级联坍缩），间隙逃逸到附近的汇。在本工作中，我们发现空位形成亚电子显微镜大小的团簇，在透射电镜下是看不见的，而间隙形成透射电镜可见的团簇。(2)进一步明确了空位型和间隙型簇的亚em尺寸与可见缺陷一起形成。(3)随着影响力的增加，TEM不可见集群有向TEM可见集群转变的趋势。这是由于在先前形成的级联附近形成的新级联所发射的能量在晶格弛豫的帮助下发生的。这种效应被现在的科学家命名为“级联能量重叠”。我们认为这种效应是由于新形成的叶栅所发出的冲击波。目前正在用超级计算机进行分子动力学模拟，研究其机理细节。(4)间隙原子向级联核心外侧强烈发射，形成TEM可见团簇。当与替换碰撞序列的距离进行比较时，发现距离相当大。我们提出间隙原子在产生的激波上通过冲激机制进行传递。这可能是为什么许多间隙点缺陷形成在集中的地方（即分组）的原因。对金属在高温辐照下损伤形成的点缺陷过程进行了广泛的研究，特别是损伤组织的演变和空洞的形成。少

In the present work, we developed the cryotransfer technique of electron microscopy of ion- and neutron-irradiated at low temperature. From the experimental results of cryotransfer TEM of ion-, fission-neutron- and fusion-neutron-irradiated metals at low temperature, the following processes are decleared for the formation and evolution of damage cascades in high energy particle-irradiated metals. (1) When the primary snock-on atom is generated in metals, it stops after the collision with other lattice atoms and forms the displacement damage cascade whose the central part is occupied by high concentration of vacancies and is surrounded by the interstitial mantle. Previously it was believed that vacancies agglomerate to form TEM visible clusters (i. e. cascade collapse) and interstitials escapes to nearby sinks. In the present work, it was found that vacancies form sub-electron microscope size of clusters which are invisible by TEM while interstitials form TEM visible clusters. (2) It wa … More s clarified that sub-EM sizes of clusters of both vacancy and interstitial type were formed together with visible defects. (3) With increasing the fluence, TEM-invisible clusters tend to change to TEM visible clusters. This occurs due to the assistance of lattice relaxation by emitted energies from new cascades formed nearby previously formed ones. This effect is named by the present scientists "cascade energy overlapping". We believe that this effect is due to the shock-wave emitted at new formed cascade. The details of mechanism is at present studying by molecular-dynamical simulation with super-computer.(4) Interstitial atoms are emitted intensely towards the outside of cascade core and form TEM visible clusters. The distance was found to be fairly larger when it was compared with that due to the replacement collision sequence. We are proposing that an interstitial atom is transported by surfriding mechanism on the shock wave generated. This may be a reason why many interstitial dot defects form at concentrated place (i. e. groupings). These point defect processes of the formation of damages in metals which are irradiated at high temperature was examined extensively especially for the damage structure evolution and void formation. Less