Structure, phase transformation and magnetic properties of SmyFe100-1.5yC0.5y alloys prepared by mechanical alloying and re-milling

The structure, phase transformation and magnetic properties of SmyFe100-1.5 y C-0.5y (y=10, 12, 14, 16, 18, 20) alloys prepared by mechanical alloying (MA) have been studied systematically. The Sm2Fe17Cx (Sm2Fe14C) phase tends to form when y is increased (decreased). For the same composition, the Sm2 Fe17Cx phase is formed more easily when the annealing temperature T-n is lo wer. No Sm2Fe14C phase is observed in the Sm20Fe70C10 alloy. In other alloy s, annealed between 650 degrees C and 950 degrees C, the Sm2Fe14C and Sm2Fe 17Cx phases coexist under a certain condition. Re-milling and re-annealing proved to be suitable for improving the magnetic properties of the MA alloy s. After annealing at 800 degrees C for 35 min, re-milling for I h and then re-annealing at 600 degrees C for 35 min, the value (BH)(max), = 10.6 MGOe has been achieved for the MA Sm14Fe79C7 alloy. After annealing at 800 degr ees C for 35 min, the MA Sm20Fe70C10 alloy was re-milled for 1 h and then r e-annealed at 550 degrees C for 2 h, resulting in the value of H-i(e) =7.96 kOe. (C) 1999 Elsevier Science S.A. All rights reserved.