| Reduced Activation Ferritic/Martensitic steels have been considered as the most promising candidate for the structural materials of the first wall/blanket for fusion reactor. In order to investigate radiation damage mechanism of the China low activation martensitic (CLAM) steel, the dissertation concentrated mainly on the microstructure analysis of CLAM steel and the SRIM code had been used to simulate the material radiation damage. Besides, the proton radiation damage of CLAM steel was probed by slow positron beam. They were:1. Microstructure analysis of CLAM steelThe metallographic and electron microscope observation showed that CLAM steel obtains the structures of lath martensite including extensive dislocation. The dislocation density in CLAM steel was estimated to be on the order of 109cm-2. Microstructure of CLAM steel and its thermal annealing behavior had been studied by Doppler technique. There exit mono-vacancies, di-vacancies, dislocations and small vacancy clusters in steel.2. Simulate the material radiation damageThe Monte Carlo code SRIM had been used to simulate the sputter yield, distribution of ions, energy of sputter atom, radiation damage of materials for bombardment by ions at different energy and different species. It would provide elementary theory for experiment.3. Proton irradiation defects in CLAM steelThe proton radiation damage of CLAM steel and the annealing behavior of defect were probed by slow positron beam. It was found that the density of vacancies increased, and the size reached a saturation value, with increasing of irradiation fluence. The whole region of irradiated sample was only slightly damaged. Small vacancies and vacancy clusters were the dominant defects, and were recovered after annealing at 400℃. Besides, the effect of minor additive Si on irradiation behavior for CLAM steel was studied. The experimental results showed that additive Si can not prevent proton irradiation defects.
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