机械合金化过程中Fe-C化合物的微结构、磁性和热性能研究

Evolution of Crystal Structure, Magnetic and Thermal Properties of Fe-C Compound during Mechanical Alloying Process

对一定原子配比的Fe-C混合粉末进行高能球磨.研究了不同球磨时间(t=60、120、180、255h)样品的微结构、磁性和热性能.结果表明,球磨过程中样品结构发生了变化,当t=180h时,有新相Fe5C2生成.当t=255h时,已形成Fe5C2单相化合物.随球磨时间的增加,样品的晶粒尺寸减小,晶格常数和晶格畸变增大.随着Fe5C2含量的增加,样品的比饱和磁化强度σs减小,矫顽力Hc和剩磁σr增加,材料由软磁性向硬磁性转变.热分析表明,金属间化合物Fe5C2具有很好的热稳定性及化学稳定性.

The Evolution of crystal structure, magnetic and thermal properties of FeC powders with different millingtime are investigated. The αFe begins to transform to Fe5C2 structure due to the diffusion of carbon into αFe when the millingtime is 180 h. With the increase of millingtime, αFe gradually disappears and finally only Fe5C2 particles are left when the millingtime is about 255 h. With the grain size decreases, both the lattice constant and lattice distortion increase. Differencing from the saturation magnetic intensity σs, the magnetic measurement implies that both the coercivity Hc and the remanence σr show a positive Fe5C2 fraction dependence, indicating that Fe5C2 particles have good hard magnetic feature. In addition, this kind of particle also shows good thermal and chemical stability.