磁场及稀土元素对Fe-C-Si系中的Si元素分布和夹杂物存在的影响

Effects of Magnetic Field and Rare Earth on the Si Distribution and Inclusions in Fe-C-Si Series

在工业纯铁中配入石墨并在高温陶瓷纤维马弗炉中制备Fe-C熔体,得到一定碳含量的Fe-C合金,再将Fe-C合金、工业纯铁以及硅铁按照需要的配比称量后放入坩埚中加热并保温,待其完全熔化后加入少量稀土元素继续保温。保温结束后,打开外磁场装置,对金属熔体施加不同磁感应强度的磁场,在施加磁场的同时,控制熔体的冷却速度,随后空冷至室温。试样制备完毕后,对试样进行打磨、粗磨、细磨、抛光处理,最后对试样进行原位分析、扫描电镜分析、能谱分析,得到Si元素浓度二维分布图和三维分布图、夹杂物形态SEM照片与典型夹杂物的成分情况。结果表明:加入稀土后,元素偏析情况得到明显改善,样品表面分布趋于均匀;在稳恒磁场和稀土元素的共同作用下,该合金体系中Si元素的偏析作用得到很好抑制,Si分布均匀,并且随着磁场磁感应强度的增大,作用效果明显;磁场力和稀土元素的共同作用对夹杂物的去除作用明显,0.8 T磁场施加后的试样中已经很难发现大颗粒夹杂物,只有少量直径在10μm左右的金属氮化物存在。

By adding graphite In the industrial pure iron,preparation of Fe-C melt in high temperature ceramic fibre muffle furnace, a certain carbon content of Fe-C alloy was obtained. In accordance with the needs of the ratio of Fe-C alloy, ferrosilicon and industrial pure iron after weighing into the crucible areheated and preserved. After it is completely melted by adding a small amount of rare earth elements, it continues to heat insulation. After the heat insulation, the external magnetic field device is opened, and the metal melt is applied to the magnetic field with different magnetic induction intensity. While the magnetic field is applied, the cooling rate of the melt is controlled, and t the air is cooled to the room temperature. After specimen preparation is completed, by grinding, coarse grinding, fine grinding,polishing treatment, through situ analysis, scanning electron microscopy analysis, energy spectrum analysis, the concentration of Si element concentration and threedimensional distribution map, the composition of SEM photos and typical inclusions are obtained. The results showed after the addition of rare earth, the segregation of elements is improved obviously, and the distribution of the sample surface tends to be uniform. Under the combined action of the steady magnetic field and the rare earth,the segregation of Si is well suppressed,the composition distribution is uniform,and the effect is more obvious with the increase of magnetic field intensity. Under the action of magnetic force and rare earth,the removal effect of the inclusions is very obvious. After the 0.8 T magnetic field treatment, it is very difficult to find the large particle inclusions,only a small amount of metal nitride with a diameter of about 10 μm.