Preparation of Iron Nitrides with Ultrahigh Magnetization by MA in NH_3

点击翻译按钮获取中文摘要

Mechanical alloying (MA) in NH_3 has been applied to prepare iron-nitride where two different kinds of iron powders, i.e., electrolytic iron powder and carbonyl iron powder, were used as the starting materials. Nitriding has proceeded better in the latter than in the former. For example, 12at%N and 2.0at%O were contained in the specimen of the electrolytic iron powder after MA in NH_3 for 160h, and 11.5at%N and 2.7at%O in the specimen of the carbonyl iron powder after the same MA time. The MA process under higher pressure of NH_3 has shown an effect on preventing oxidation.The specimen obtained by the above mentioned MA process showed a supersaturated bcc structure below 14-15at%N,and Fe_3N structure above 18-19at%N.Fe_<16>N_2 could not obtained by the MG process for the 11.1at%N specimen prepared by the MA process. Fe_4N,however, obtained by the annealing treatment.The MA process in NH_3 has been also applied for the preparation of Sm_2Fe_<17>N_X specimen. The Sm_2Fe_<17>N_X specimen obtained by this process has been confirmed to show the ultra high coercivity higher than 2.0T.This experiment would be continued to get the nano-composite magnetic materials composed of Fe_<16>N_2 and Sm_2Fe_<17>N_X.