Study of cascade damage effects detected by dynamic behavior of helium bubbles

（1）氦泡动力学行为检测的级联损伤效应研究在阿贡国家实验室，用10 keV氦离子辐照预引入氦泡的Au、Cu、Si、Fe和Fe-Cr合金样品，用原位IVEM观察研究了高能自离子辐照过程中氦泡的动力学行为。氦泡可以作为叶栅损伤的传感器。结果表明，即使在高温高能自离子辐照下，大部分气泡仍表现出布朗型随机运动，但其运动性受到抑制。但是，少数泡沫被加速了。气泡的凹陷和加速应分别由空位的吸收和与离子的直接碰撞引起。在中等温度下，气泡的随机运动不会发生，而氦气泡沿着位错环的间歇运动会发生。 关于我们 在高能自离子辐照下诱导。氦泡在这些温度下沿着位错线容易运动。在较低的温度下，一个零星的运动在有限的区域被发现，这可能是由于直接碰撞与级联损坏。（2）氦泡与位错的相互作用及位错环的一维运动氦泡与位错的相互作用较强。结果表明，小气泡是热移动的沿着位错线和其他方向。气泡可以作为位错中应变场的传感器，研究了Burgers矢量为1/2的间隙型位错小环<111>在退火过程中或在电子辐照下的一维运动，发现一维运动时Burgers矢量变为另1/2<111>或变为<100>。在较低的温度下，在Fe-9 Cr中的环的数密度增加，这表明，一维运动可以诱导它们的弹性相互作用。（3）研究了氦辐照Fe和Fe-9 Cr合金的热脱附谱（TDS）及其与显微组织变化的关系。在1000℃的恒温加热过程中，观察到5个TDS峰。在较低温度下的峰值与位错捕获相关，而在较高温度下的峰值与气泡向表面的运动和α-γ相变相关。Fe-9 Cr合金中Cr偏聚到气泡或位错环中，使TDS峰向高温移动。少

(1)Study of cascade damage effects detected by dynamic behavior of helium bubblesHigh energy (100-400keV) self-ions were irradiated to Au,Cu,Si,Fe and Fe-Cr alloys specimens, to which helium bubbles were pre-introduced by irradiation with 10keV helium ions, and the dynamical behavior of the bubbles during the irradiation of high energy self-ions was studied by in-situ IVEM observation at Argonne National Laboratory. Helium bubbles can be used as a sensor for the cascade damage. It was found that most of the bubbles showed Brownian type-random motion even under the irradiation with high energy self-ions at high temperature, but their mobility was depressed. But, a small number of the bubble were accelerated. The depression and the acceleration of the bubbles should be caused by absorption of vacancies and by direct collision with ions, respectively. At middle temperatures, random motion of the bubble did not occur and an intermittent motion of helium bubbles along a dislocation loop was … More induced under the irradiation with high energy self-ions. Easy motion of helium bubbles along the dislocation lines at these temperatures was revealed. At lower temperatures, a sporadic motion in a limited region was revealed and this could be caused by direct collision with the cascade damage.(2)Interaction of the bubble with dislocation and one-dimensional motion of dislocation loopsThe interaction of helium bubbles with the dislocation was comparatively strong. It was revealed that the small bubble was thermally mobile along the dislocation line and the other directions. Bubbles can be used as a sensor of the strain field in the dislocation.One-dimensional motion of the small interstitial type dislocation loops with the burgers vector 1/2<111> was studied during annealing or under the electron irradiation and it was revealed that the burgers vector changes to the other 1/2<111> or to <100> during the one-dimensional motion. At lower temperature, the number density of the loops increases in Fe-9Cr and it was suggested that one dimensional motion could be induced by their elastic interaction.(3)TDS(Thermal Desorption Spectroscopy) of helium and its correlation with a change of the microstructure in Fe,Fe-9CrTDS spectra from helium irradiated Fe and Fe-9Cr and the correlated microstructure changes were studied. During a constant heating of the specimen up to 1000℃, five TDS peaks were observed. The peaks at lower temperatures are correlated with the dislocation trapping and ones at higher temperatures are correlated with the bubble motion to the surface and alpha-gamma phase transformation. Chromium segregated to the bubble or dislocation loops could shift the TDS peaks to higher temperature in Fe-9Cr alloy. Less