氧化铝/氧化镧X射线衍射及拉曼光谱研究

当钢中氧化铝夹杂物的尺寸过大、棱角分明，在线材拉拔为钢丝的过程中可视为主要的裂纹源，会严重影响钢材性能，细化或去除钢中夹杂物备受重视。由于钢中合金元素添加量相对于钢液较小，并在实验及分析的中间过程中存在误差，使用放大夹杂物反应的思路，研究了在高温1 600 ℃时，不同比例稀土氧化镧粉末和氧化铝粉末的添加量对夹杂物的物相变化、尺寸大小的影响。对高温箱式炉设定程序进行升温、保温、随炉冷却，使用X射线衍射仪、拉曼光谱仪测试结果分析了镧铝氧化物的具体变化过程。结果表明：随着La₂O₃添加量的不断增加，最先生成LaAl₁₁O₁₈相，其次为LaAl₁₁O₁₈，LaAlO₃相，峰强减弱，半高宽增加，晶粒尺寸变小，随后LaAl₁₁O₁₈特征峰消失，只剩下LaAlO₃相，且并无新相生成。结合H-W平均晶粒尺寸数学模型计算R2分别为0.990 25，0.962 59，0.987 1和0.989 76，且1#样品到4#样品晶粒尺寸分别为6.08，2.88，7.67和4.75 μm，2#样品晶粒尺寸最小，3#样品晶粒尺寸最大，表明合适的氧化镧和氧化铝配比可以促进形核并缩小晶粒尺寸。通过拉曼光谱分析得出，随着Al₂O₃配比的减少，观察拉曼位移在4 385 cm-1处拉曼特征峰消失，结合XRD图谱可以判定该处为LaAl₁₁O₁₈相。3#-4#曲线在拉曼位移为3 564～3 642和4 461～5 554 cm-1处出现拉曼特征峰，结合2#曲线以及XRD图谱可知，生成新的LaAlO₃相，且3#样品和4#样品的不同配比对拉曼峰强无太大影响，也没有出现新的特征峰。通过放大钢中需要针对性研究的物质，分析了氧化镧粉末添加后对氧化铝粉末改性的演变过程。研究结果可对实际炼钢过程中解决氧化铝夹杂物改性的问题提供参考。

Study on Alumina/Lanthanum Oxide X-Ray Diffraction and Raman Spectroscopy

When the size of aluminum oxide inclusions in steels is too large and the edges and corners are sharp, they can be regarded as the main source of cracks during the process of steel wire drawing, and these cracks substantially affect the performance of the steel. The refinement or removal of inclusions in steel is important. Since the amount of alloying elements added to steel is relatively small compared to that in the molten steel and there are errors during the experiments and analyses, the reaction of inclusions is magnified and studied by varying the proportions of rare earth lanthanum oxide powder and alumina at a high temperature of 1 600 ℃. The amount of powder that is added affects the phase change and size of the inclusions. A high-temperature box furnace is set to increase the temperature, keep warm and cool, and X-ray diffraction and Raman spectrometry are used to analyze the specific changes of lanthanum aluminum oxide. The results show that with increasing amounts of La₂O₃, the LaAl₁₁O₁₈ phase is formed first, followed by the LaAl₁₁O₁₈ and LaAlO₃ phases. As the peak intensity decreases, the full width at half maximum increases and the grain size decreases. Then, the characteristic peak intensity of LaAl₁₁O₁₈ disappears, leaving only a decreased amount of the LaAlO₃ phase, and no new phase is formed. Combined with the mathematical model for the average grain size of HW, R2 for samples 1#, 2#, 3# and 4# is calculated to be 0.990 25, 0.962 59, 0.987 1, and 0.989 76, and the grain sizes are 6.08, 2.88, 7.67, and 4.75 μm, respectively. Sample 2# has the smallest grain size herein, and sample 3# has the largest grain size herein, indicating that an appropriate ratio of lanthanum oxide and aluminum oxide can promote nucleation and reduce the grain size. Through Raman spectrometry, it is observed that with a decrease in the Al₂O₃ ratio, the Raman characteristic peak at 4 385 cm-1 disappears. When these results are combined with those from XRD, it is determined that the LaAl₁₁O₁₈ phase is present. Samples 3# and 4# have characteristic Raman peaks from 3 564～3642 and 4 461～5 554 cm-1, respectively. Upon combining the Raman peaks and XRD pattern for sample 2#, a new LaAlO₃ phase is generated. The different ratios of the samples have little effect on the Raman peak intensity, and no new characteristic peaks appear. By enlarging the materials in steels that need targeted research, the evolution process of the modification of alumina powder after the addition of lanthanum oxide powder is analyzed. The research results can reference solving the problem of alumina inclusion modification during the actual steelmaking process.