【摘要】 用机械合金化方法制备了具有单斜晶体结构的纳米晶、硬磁性、单相Fe5C2化合物粉末和软磁性好的纳米晶Fe55Ni45(f.c.c)过饱和固溶体粉末及纯α-Fe(b.c.c)超细粉末。并将上述硬磁和软磁粉末按一定的原子百分比混合后继续球磨10h,生成Fe5C2α-Fe双相结构的复合材料。发现制备态复相材料的饱和磁化强度Ms高于制备态单相Fe5C2,而矫顽力Hc比制备态Fe5C2略低。当样品在相变温度以下进行低真空退火后其磁性得到更大提高。发现400°C真空退火后,成分为(Fe5C2)94(Fe55Ni45)6的复相样品,其饱和磁化强度Ms和矫顽力Hc比制备态单相Fe5C2样品分别高出37%和48%,比退火态单相Fe5C2样品分别高出18%和12%。实验证实纳米晶Fe5C2α-Fe双相复合材料具有较优的综合硬磁性,有望成为一种新的磁记录介质,并对这一实验结果进行了讨论。更多还原

【Abstract】 Single phase Fe₅C₂ intermetallic compound and the supersaturated solution Fe₅₅Ni₄₅、α-Fe etc nanocrystalline powders were prepared by mechanical alloying method. The former was of hard magnetism and the later was of good soft magnetic properties. The double phase Fe₅C₂/α-Fe powder was produced by the mixturing and milling of the soft magnetic powder and the compound Fe₅C₂ powder continuously up to 10 hours. It is found that the Fe₅C₂ powder was monoclinic crystal structure, the Fe₅₅Ni₄₅ is FCC crystal structure, the α-Fe is BCC crystal structure and the composite material Fe₅C₂/α-Fe is double phase structure. The crystallite grain size and crystal lattice strain of mono-phase are calculated by Cauchy distribution function. The lattice constants were calculated by least square method. Their magnetic properties were measured with vibrating sample magnetometer. It was shown that the hard magnetic properties of the composite phase Fe₅C₂/α-Fe were improved. As far as the samples of prepared state concerned, the saturation magnetism Ms of composite phase samples was higher than single phase Fe₅C₂, though Hc of double phase samples was less decreased. When these samples were annealed in vacuum system under phase transformation temperature, their magnetic properties including Ms, Hc were further improved. We found that the Ms and Hc of the annealled composite sample （Fe₅C₂）₉₄(Fe₅₅Ni₄₅)₆ increased by 37% and 48% compared with the prepared state Fe₅C₂ and by 18% and 12% than the annealled state Fe₅C₂, respectively.更多还原