硅钢具有高矫顽力、低磁导率、大电阻系数等优点,被广泛应用于制造变压器和电机的铁芯材料。添加Nb元素可以提升硅钢的电磁性能,同时细化晶粒,提高力学性能。对Fe-Nb-Si三元合金研究应用的基础是三元相图的研究,本工作通过X射线衍射分析(XRD),扫描电子显微镜(SEM)和电子探针显微分析(EPMA/WDS)等表征手段,对Fe-Nb-Si三元体系1 173 K和1 073 K下的相平衡进行了分析研究。两个温度下均测得了11个三相平衡区,发现三种三元化合物τ2(FeSi2Nb2)、τ5(Fe4Si7Nb4)、τ6(FeSiNb)。1 173 K和1 073 K下,Nb在η相(Fe5Si3)中的最大固溶度分别约为1.6%(摩尔分数,%,下同)和0.5%,Fe在αNb5Si3的最大固溶度分别约为5.8%和4.9%,Si在Fe2Nb中的最大固溶度分别为24.3%和25.2%,Si在μ(FeNb)中的最大固溶度分别为13.4%和11.3%。本工作完善了Fe-Nb-Si三元体系的相图信息,为后续开发新型硅钢提供了理论依据。
Because of high coercivity, low permeability and large resistivity, silicon steel is widely used in the manufacture of iron core materials for transformers and various motors. On the basis of silicon steel, the addition of Nb element can improve the electromagnetic properties of silicon steel, and at the same time refine the grains and improve its mechanical properties. The research and application of Fe-Nb-Si ternary alloy is based on the study of ternary phase diagram. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA/WDS) were used to analyze the Fe-Nb-Si ternary system at 1 173 K and 1 073 K. The following phase equilibrium was experimentally investigated. The results show that 11 three-phase equilibrium zones are measured at two temperatures, and three ternary compounds τ2(FeSi2Nb2)、τ5(Fe4Si7Nb4)、τ6(FeSiNb)are found. Themaximum solid solubility of Nb in η phase (Fe5Si3) is about 1.6% (mole fraction, %, the same below) at 1 173 K and 0.5% at 1 073 K. The maximum solid solubility of Fe in αNb5Si3 is about 5.8%at 1 173 K and 4.9% at 1 073 K. The maximum solid solubility of Si in Fe2Nb is 24.3% at 1 173 K and 25.2% at 1 073 K. The maximum solid solubility of Si in μ phase (FeNb) is up to 13.4% Si at 1 173 K and only about 11.3% at 1 073 K. This work improves the phase diagram information of the Fe-Nb-Si ternary system and provides a theoretical basis for the subsequent development of new silicon steel.
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