不同LaFe11.6×xSi1.4合金中1∶13相的Fe原子平均磁矩研究
The Magnetic Moment of Fe Atom in 1∶13 Phase for Different LaFe11.6×xSi1.4 Alloys
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摘要:通过实验手段, 系统研究了在不考虑缺陷的情况下, 02T磁场范围内, 纯Fe和不同LaFe11.6×xSi1.4合金中Fe原子的平均磁矩.结果表明, 在180、185、190、195K时, 纯铁的饱和磁矩均为213A·m2/kg, 每个Fe原子的平均饱和磁矩为2.12μΒ.LaFe11.6Si1.4合金中1∶13相的饱和磁矩理论值应该为166A·m2/kg, 等温磁熵变的实验最大值为41.5J/kg·K.采用非自耗电弧炉熔炼的LaFe11.6Si1.4纽扣合金, 通过高温短时热处理后, 在180K的最大磁化强度只有112A·m2/kg, 合金中1∶13相的Fe原子的平均磁矩为1.43μΒ, 1个1∶13相晶胞中对合金磁矩有贡献的有效Fe原子数为7.8个.通过中频感应炉制备的千克级LaFe11.6Si1.4合金, 在相同温度下1∶13相的磁化强度也只有125A·m2/kg, 其Fe原子的平均磁矩为1.59μΒ, 1个晶胞中对合金磁矩有贡献的有效Fe原子为8.7个.但在LaFe11.6×xSi1.4 (x>1) 试样中, 过量Fe对该合金的磁化强度有明显的增强作用.在180K温度下, LaFe11.6×1.05Si1.4和LaFe11.6×1.1Si1.4合金中1∶13相的技术饱和磁化强度分别为146A·m2/kg和155A·m2/kg, Fe的平均有效磁矩约达到1.86μΒ, 明显高于正常化学计量比LaFe11.6Si1.4中1∶13相中Fe原子的平均有效磁矩.Abstract:Without considering the defects, a systematic investigation is conducted, by means of experiment, to determine the average magnetic moment of Fe atom in pure Fe and different LaFe11.6×xSi1.4 alloys.The results show that the saturation magnetic moments of pure Fe are 213 A·m2/kg at 180, 185, 190, and 195 K;the average saturation magnetic moment of every single pure Fe atom is 2.12μB.The theoretic value of the saturation magnetic moment of LaFe11.6Si1.4 alloy should be 166 A·m2/kg emu/g, and the experimental value of the isothermal magnetic entropy change is 41.5 J/kg·K.The maximum magnetization of LaFe11.6Si1.4 alloy melted by non-consumable arc furnace and annealed by short-time high-temperature heating is only 112 A·m2/kg, and the average magnetic moment of the Fe atom of 1:13 phase in the alloy is 1.43μB;In one LaFe11.6Si1.4 crystal cell, there are 7.8 effective Fe atoms which have made contribution to the magnetic moment of the alloy.The magnetization of LaFe11.6Si1.4 kg alloy produced by medium-frequency induction furnace under the same temperature is only 125 A·m2/kg, whose average magnetic moment of Fe atom is 1.59μB, and in each LaFe11.6Si1.4 crystal cell there are 8.7 effective Fe atoms that have contribution to the alloy magnetic moment.However, excess Fe in the LaFe11.6×xSi1.4 samples has a significant effect on enhancing the magnetization.The technique saturation magnetization of 1∶13 in LaFe11.6×1.05Si1.4 and LaFe11.6×1.1Si1.4 alloys are 146 A·m2/kg and 155 A·m2/kg, respectively.The effective magnetic moment of Fe atom reaches about 1.86μB which is significantly higher than the average effective magnetic moment of Fe atom of 1:13 phase in LaFe11.6Si1.4.