强流脉冲电子束辐照诱发纯钼表面的损伤效应及结构缺陷

利用强流脉冲电子束（HCPEB）装置对纯钼表面进行辐照处理，并利用X射线衍射仪，扫描电子显微镜（SEM）、透射电子显微镜（TEM）详细分析了辐照表面的微观结构和损伤效应. 1次HCPEB辐照后，纯钼表层积聚了极大的残余应力，多次辐照后表面未融化区域出现大量绝热剪切带，且局部区域发生开裂. 微观结构分析显示，辐照后材料表面形成发散状的位错组态和大量空位簇缺陷；绝热剪切带内部是尺寸为1 μm 左右等轴状的再结晶晶粒. 剪切带造成的材料表面局部软化以及间隙原子偏聚于晶界是材料发生开裂的主要原因. 另外，表面熔化区域可形成尺寸为20 nm左右的纳米晶. 关键词： 强流脉冲电子束 纯钼 绝热剪切带 空位簇缺陷

Damage and structural defects in the surface lager of pure molybdenum induced by high-current pulsed electron beam

High-current pulsed electron beam (HCPEB) technique was applied to induce the surface irradiation of pure molybdenum. Microstructures and damaging effect of the irradiated surface were investigated in detail by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After 1 pulse of HCPEB irradiation, a high level of residual stress is amassed in the irradiated surface layer, while after several pulses of irradiation, a large number of adiabatic shear bands are formed on the unmelted regions of the surface, and local cracking occurs in these regions. Microstructure observations show that scattered dislocations and large amounts of vacancy clusters are formed on the irradiated surface. The adiabatic shear bands are composed of fine recrystallized grains with an average size about 1 μm. The partial softening of the irradiated surface induced by adiabatic shear bands, and the segregation of interstitial atoms in grain boundaries are primarily responsible for the surface cracking of the material. Further, nanocrystallines (20 nm) are also formed in some melted regions of the surface.
Keywords： HCPEB pure molybdenum adiabatic shear band vacancy defect clusters