【摘要】：材料問題一直是制約未來先進核能發(fā)展的主要瓶頸之一。先進核能裝置處于高溫、高通量中子輻照等惡劣環(huán)境中,中子輻照不但可以在材料中引起嚴重的位移損傷,同時中子引起的核嬗變反應在材料中產(chǎn)生了大量的He原子。He原子在材料中具有低的溶解度,在高溫下發(fā)生遷移聚集成He泡。位移損傷和He摻雜行為導致材料微觀結構變化和宏觀性能下降,進而影響反應堆的運行安全。燒結Si C是一種具有高熔點、高耐腐蝕性、高熱導率、低熱膨脹系數(shù)和低中子反應截面的陶瓷材料,被認為是有潛力的可用于先進核能裝置的候選材料之一。目前國內(nèi)外主要研究的是單晶Si C,對于多晶燒結Si C的研究相對缺乏、不系統(tǒng)。論文對多晶燒結Si C的He離子輻照損傷進行了初步研究,作為對比,對單晶6H-Si C中的He行為也做了較深入研究。針對不同溫度不同注量下He離子輻照引起的Si C材料宏觀性能和微觀結構的變化,采用多種測試手段對兩種Si C材料He離子輻照損傷進行了研究,主要結論如下:1.單晶6H-Si C中He行為研究。拉曼散射光譜結果表明:高注量室溫下輻照會使晶體出現(xiàn)非晶化;高溫下輻照伴隨著晶體缺陷的恢復過程,氦泡的存在會抑制缺陷恢復。高分辨XRD結果表明:高注量室溫下輻照,曲線出現(xiàn)了漫散射;高溫下輻照,隨著注量的增大,近表面應變和最大應變峰向小角度方向移動。2.燒結Si C中He行為研究。拉曼散射光譜結果表明:隨著注量的增加拉曼峰強度不斷減小,這與損傷層吸收系數(shù)的增大有關。納米壓痕結果表明:高注量室溫下輻照,非晶層包殼效應引起輻照樣品納米硬度低于未輻照樣品;600℃高溫下輻照時,隨著注量的增加納米硬度逐漸增加,這是間隙型位錯環(huán)所引起的。TEM結果表明:He泡在晶粒內(nèi)和晶界處的密度和形貌與He離子輻照劑量有關。3.對比研究燒結Si C和單晶6H-Si C中的He行為。相同輻照條件下,6H-Si C的拉曼光譜出現(xiàn)了Si-Si鍵的振動模式;燒結Si C顯示出更大的硬度差;He泡更容易在燒結Si C中形核和長大。
[Abstract]:Material problem has been one of the main bottlenecks restricting the development of advanced nuclear energy in the future. Advanced nuclear power plants are in harsh environments such as high temperature and high throughput neutron irradiation. Neutron irradiation can not only cause serious displacement damage in materials, At the same time, the neutron induced nuclear transmutation produced a large number of He atoms in the materials. The He atoms have low solubility in the materials and migrate and aggregate into He bubbles at high temperature. Displacement damage and He doping behavior lead to the change of microstructure and the decrease of macroscopic performance of the material, which will affect the safety of the reactor. Sintered Si C is a kind of ceramic material with high melting point, high corrosion resistance, high thermal conductivity, low thermal expansion coefficient and low neutron reaction cross section. At present, the main research at home and abroad is single crystal Si C, the study of polycrystalline sintering Si C is relatively scarce and not systematic. In this paper, the radiation damage of He ions in polycrystalline sintered Si C has been studied. As a comparison, the He behavior in single crystal 6H-Si C has also been studied. Aiming at the changes of macroscopic properties and microstructure of Si C materials induced by He ion irradiation at different temperatures and different doses, the damage of He ion irradiation on two kinds of Si C materials was studied by a variety of test methods. The main conclusions are as follows: 1. Study on He behavior in single Crystal 6H-Si C. The Raman scattering spectra show that irradiation at high flux room temperature will lead to the crystallization of the crystal, and the existence of helium bubble will inhibit the defect recovery when the irradiation is accompanied by the recovery process of the crystal defect at high temperature. The results of high resolution XRD show that diffuse scattering appears at room temperature, and the peak of near surface strain and maximum strain shift to small angle with the increase of flux at high temperature. 2. Study on He behavior in sintered Si C. The Raman scattering spectra show that the intensity of Raman peak decreases with the increase of the flux, which is related to the increase of the absorption coefficient of the damaged layer. The results of nanocrystalline indentation show that the nanocrystalline hardness of irradiated samples is lower than that of unirradiated samples due to the cladding effect of amorphous layer at high Fluence at room temperature. When irradiated at 600 鈩，

本文編號：2409721