【作者】 王欣；

【导师】 杨胶溪；

【作者基本信息】 北京工业大学 ， 光学工程， 2014， 硕士

【摘要】 随着我国核电事业的快速发展，对作为核反应堆结构材料的要求越来越高。锆合金作为重要的结构部件和包壳材料，普遍用于核动力反应堆中。采用激光高能束流集中作用在锆合金表面，使得锆合金表面改性以更好应用于实际工况。利用扫描电子显微镜(SEM)、透射电镜（TEM）、能谱仪(EDS)、X射线衍射(XRD)、拉曼等手段对锆合金的微观组织形貌、成分及物相进行分析。利用热膨胀仪、探针式表面轮廓仪、高压反应釜来表征锆合金的热膨胀系数、粗糙度、耐蚀性等性能指标。结果表明：用微弧氧化+准分子激光复合处理锆合金可以得到无纵向裂纹的氧化膜。膜的厚度约为6μm，表面平滑、粗糙度低；该复合处理可使微弧氧化工艺得到的m-ZrO2的相对含量显著减少，而t-ZrO2相对增加；复合处理的锆合金比原始样品的热膨胀系数变小；相同工艺参数下，随着功率的提高基本上呈现耐蚀性能先增强后减弱的趋势。最佳工艺参数是单脉冲功率500mJ，脉冲数在2400左右，此工艺参数的样品在360℃、18.6MPa、0.01mol/LLiOH的高压釜中经94天的腐蚀增重为29mg/dm2，优于Zr-1Nb锆合金的43.5mg/dm2。用CO2激光熔凝的手段处理锆合金。Zr-1Nb样品以板条状的α-Zr为主，第二相大量存在于基体中，其中圆球形第二相为Cr0.5Fe1.5Zr，圆棒形第二相为Fe3Zr。激光熔凝样品位错密度比较高。基体相为α-Zr，并有第二相Zr6Fe3O。激光功率在420W到540W，施加激光功率越低，耐蚀性能越强。通过ANSYS软件模拟CO2激光熔凝锆合金板的过程。激光熔凝锆板后，锆板上部为熔凝区，下部为硬化区。熔池随着功率的升高都会有所扩大。激光的快速加热和冷却作用来改善锆板的组织形貌，进而影响其耐蚀性能。更多还原

【Abstract】 With the rapid development of Chinese nuclear power industry, nuclear reactorstructural material becomes more and more important and it takes our attentiongradually. Especially, zirconium alloys are important structural components andcladding materials, which are commonly used in nuclear reactors. In order to improvethe corrosion property of zirconium alloys in actual working conditions, the surface ofthe Zr-1Nb alloy was modified by laser processing technology.Scanning electron microscopy (SEM), transmission electron microscopy (TEM),energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman and othertesting methods were used to characterize microstructure morphology, compositionand phase constituent of zirconium alloy. Thermal expansion instrument, probe typesurface profiler and autoclave were performed to characterize thermal expansioncoefficient, roughness and corrosion resistance.Dense, smooth, flat oxidation films were formed without cracks by means ofmicroarc oxidation (MAO)+Laser to zirconium alloys. Compared to MAO samples,the samples after Hybrid treatment had lower surface roughness and thermalexpansion coefficient. It was found that all the oxidation flms consisted of monoclinicZrO2and tetragonal ZrO2phases with the thickness of6μm. This Hybrid processingreduced m-ZrO2significantly and increased t-ZrO2relatively. Under the sameprocessing parameters, the corrosion resistance firstly increased with increasing laserpulse energy substantially, after reaching a certain value, and the corrosion resistancedeclined. The optimized parameters were500mJ single-pulse power,2400pulsesnumber. Therefore, the lowest weighted gain of the laser Hybrid processing sampleswas about29mg/dm2in autoclave experiments on the conditions of360℃,18.6MPa,0.01mol/L LiOH and94days, which better than Zr-1Nb alloys of43.5mg/dm2.According to experiment results of the Zr-1Nb alloy samples after CO2laserremelting process. The surface microstructure of Zr-1Nb alloy was mainly of wattleα-Zr. Second-phase was dispersed in the matrix in a large number, in whichprecipitated sphericity was Cr0.5Fe1.5Zr, whereas rod-shaped phase was Fe3Zr. Incontrast, The dislocation density of laser remelting samples was relatively high.Matrix phase was α-Zr, and the second-phase was Zr6Fe3O. When laser power rangedfrom420W to540W, the lower the laser power was applied, the higher corrosion resistance was got.ANSYS software was used to simulate the CO2laser remelting process onzirconium alloy plate. After laser remelting zirconium plate was divided into tworegions in which the upper part was melted area, the lower part was hardened zone. Asthe power increased, the melted layer gradually became larger. The effect of rapidheating and cooling in the laser remelting process improved the microstructure of thematerial, thereby affecting its corrosion resistance.更多还原