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

(1)利用氦泡动力学行为检测级联损伤效应研究采用高能（100-400keV）自离子辐照Au、Cu、Si、Fe和Fe- cr合金试样，在10keV的氦离子辐照下预先引入氦泡，并在Argonne国家实验室进行原位IVEM观测，研究了高能自离子辐照过程中气泡的动力学行为。氦气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，气泡大部分仍表现出布朗型随机运动，但其迁移率受到抑制。但是，一小部分气泡被加速了。气泡的沉降和加速应分别由空位的吸收和离子的直接碰撞引起。在中等温度下，气泡不发生随机运动，在高能自离子的照射下，气泡沿位错环产生间歇性运动。在这些温度下，氦气泡沿位错线容易运动。在较低的温度下，在有限的区域内显示出零星的运动，这可能是由与级联损伤的直接碰撞引起的。(2)气泡与位错的相互作用及位错环的一维运动氦气泡与位错的相互作用较强。结果表明，小气泡沿位错线和其他方向热移动。气泡可以作为位错中应变场的传感器。在退火和电子辐照条件下，研究了burgers向量为1/2<111>的小间隙型位错环的一维运动，发现在一维运动过程中，burgers向量变为另1/2<111>或<100>。在较低温度下，Fe-9Cr中环的数量密度增加，表明它们的弹性相互作用可能引起一维运动。(3)研究了氦辐照Fe和Fe- 9cr的热解吸光谱（TDS）及其与Fe、Fe- 9cr微观结构变化的相关性。在试样持续加热至1000℃时，观察到5个TDS峰。低温峰与位错捕获有关，高温峰与气泡向表面运动和α - γ相变有关。在Fe-9Cr合金中，析出的铬可以使TDS峰向更高的温度移动。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