Evaluation of size distribution of small inclusions dispersed in molten steel by small angle diffraction high brilliant X ray

Ti氧化物具有多种不同的晶体结构，其结构随Fe-Ti-O体系中Ti含量的不同而不同。此外，它们与Fe氧化物形成化合物和固溶体。因此，了解具有不同晶体结构（不同晶格间距）的Ti氧化物的沉淀行为对于发展氧化物冶金技术是非常重要的。因此，作为第一步，和热力学评估的脱氧平衡的各种钛氧化物已进行。(1)利用EBSD对Fe-Ti-O合金熔体中产生的约1μm的Ti氧化物进行了物相鉴定。在此基础上，准确地确定了Fe-Ti-O系熔体与不同钛氧化物平衡时的氧浓度范围。(2)对于Fe-Ti-O系熔体，用差热分析法测定了其形核起始温度，并对Fe-Ti-O系熔体中Ti氧化物的形核生成温度进行了测定，发现其形核起始温度随熔体中Ti含量的变化而变化。此外，为了建立二维沉淀行为与实际三维行为之间的相关性，通过使用显微镜观察溶液中CaCO_3的沉淀行为。基于分形模型对二维和三维降水行为的相关性进行了评价。沿着这些实验的进行，发现同步辐射小角度分析钢液中析出粒子是相当困难的。因此，用常规的X射线小角衍射分析法对CaCO_3从溶液中的成核行为进行了分析，证实了对直径达10μm左右的颗粒进行分布评价是可能的。

Ti oxides have a lot of different crystal structures, and their structures varies depend on Ti concentration in the Fe-Ti-O system. Furthermore, they form compounds and the solid solutions with the Fe oxide. Therefore, understanding of the precipitation behavior Ti oxides that have a various crystal structure (various lattice distance) can be very important to develop the oxide metallurgy technology. Thus, as first step, and thermodynamic evaluation of the deoxidation equilibrium of various Ti oxides have been carried out. (1) The phase identification of Ti oxide of about 1μm generated in melt Fe-Ti-O alloy was carried out by using EBSD. Based on the results, the range of the oxygen concentration of molten Fe-Ti-O system in equilibrated with various Ti oxides melt Fe-Ti-O alloy was accurately determined. (2) For molten Fe-Ti-O system, the nucleation starting temperature was measured by using DTA, measurement of the nucleation generation temperature of the Ti oxide from melt Fe-Ti-O alloy was carried out, and it has been found that the nucleation gstarting temperature vary based on Ti concentration in molten Fe-Ti-O system. Moreover, to establish the correlation between the 2-dimensional precipitation behavior and actual 3-dimensional behavior, CaCO_3 precipitation behavior from the solutions was observed by using the microscope. The correlation of precipitation behavior in two dimensions and three dimensions was evaluated based on the Fractal model. Along with carrying those experiments, it was found that the small angle analysis of precipitated particles in the molten steel by synchrotron radiation is rather difficult. Therefore, the nucleation behavior of CaCO_3 from the solution was analyzed by using conventional X-ray with small angle diffraction analysis, and was confirmed that the distribution evaluation was possible for the particles with up to the diameter of about 10μm.