机械合金化制备的Fe1-xCx固溶体的结构和磁性研究

1IntroductionIt is well known that the solubility of carbon in Fefor both body-centered-cubic (bcc) and face-centered-cubic (fcc) structures is very low, even in a liquidstate. The maxi mum solubility of carbon in ferrite isonly about 0 .1 atompercent .The difference of atomicradius between Fe and C is so large that C is em-bedded at the interstitial site in the bcc or fcc Fe lat-tice . Hume-Rothery rules suggest that the atomic sizeof the solute and solvent should differ by less than15 %to…

Structure and Magnetic Properties of Fe1- x Cx Solid Solution Prepared by Mechanical Alloying

Supersaturated solid solutions Fe1-x Cx (0≤x≤0.9) of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤x≤0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and coercivity Hc is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in α-Fe extended by nanocrystalline phase formation is discussed.