固体渗硅制备的Fe-6.5 mass%Si合金的组织演变与磁性能

Microstructural evolution and magnetic properties of Fe-6.5 mass%Si alloy prepared by solid powder siliconizing treatment

对3mass%冷轧硅钢板材进行固体渗硅和扩散退火处理,采用扫描电镜和X射线衍射仪等研究了其组织、物相和板材厚度方向Si成分的演变,并对其在不同频率下的铁损进行分析。结果表明:经过850℃的固体渗硅后,可在板材上制备出致密的化合物层,化合物层由表面的FeSi相层和邻近的Fe3Si相层构成;随着渗硅时间的增加,FeSi相层厚度不变,Fe3Si相层厚度增加;当板材心部完全形成Fe3Si相后,FeSi相层厚度开始增大。在扩散退火过程中,板材表面化合物层中Si向心部扩散,最终形成Si沿厚度方向均匀分布的、由单一α-Fe相构成的Fe-6.5 mass%Si合金。在较低的频率(1000 Hz)下,Fe-6.5 mass%Si合金的铁损高于3 mass%硅钢;在中等频率下(1000-20000 Hz),二者铁损接近;在较高的频率下(>20000 Hz),Fe-6.5 mass%Si合金的铁损小于3 mass%硅钢,频率越高差异越大。

The 3 mass% cold-rolled silicon steel sheet was subjected to solid powder siliconizing and diffusion annealing treatment, and microstructural evolution, phase transformation and Si distribution along the depth were studied by scanning electron microscopy and X-ray diffractometer, and the iron losses at different frequencies was measured. The results show that after the solid powder siliconizing at 850 ℃, a dense compound layer can be prepared on the surface of the 3 mass% cold-rolled silicon steel sheet, which consists of a FeSi phase layer near the top surface and a Fe3Si phase layer between the surface and the α-Fe matrix. With the increase of the siliconizing time, the thickness of the Fe3Si phase layer increases, and the thickness of the FeSi phase layer remains unchanged, and then begins to increase when the α-Fe phase of the matrix completely transforms into Fe3Si phase. During the diffusion annealing, Si riched in the compound layer diffuses to the center of the sheet, resulting in the formation of Fe-6.5 mass% Si alloy with Si uniformly distributed along the thickness direction and composed of a single α-Fe phase. At lower frequencies(1000 Hz), the iron loss of the Fe-6.5 mass%Si alloy is higher than that of the 3 mass% silicon steel;at moderate frequencies(1000-20000 Hz), the iron loss of the two steels is close;at higher frequencies(>20000 Hz), the iron loss of the Fe-6.5 mass%Si alloy is less than that of the 3 mass% silicon steel, the higher the frequency, the greater the difference.