Magnetism of Rapidly Quenched Amorphous Fe-Sm Alloys

The structural analysis and investigation of magnetic properties were carried out on rapidly quenched Fe_100-x Sm_x (10.5 ≤ × ≤ 80) alloys. Amorphous alloys were fabricated in a wide composition range from x = 17 to 72.5. The composition dependence of Curie temperature and magnetization was found to be similar to that of amorphous Fe-(Nd, Pr) alloys and could be considered to be caused by the change in short-range atomic order with Sm concentration. A maximum coercive force of about 1.1 kOe at 300 K and 12 kOe at 77 K is obtained in x = 40 alloy. The rapid decrease in coercive force on raising temperature can be explained by the wall pinning model proposed by Gaunt. After heating the amorphous alloys up to 900 K, they transform into metastable Fe₅ Sm (T_c = 465 K) + α - Fe (x < 20), unknown metastable phase (T_c = 555 K) + α - Fe (20 ≤ × ≤ 33.3) and Fe₂ Sm (T_c = 670 K) + Sm (x ≥ 40).