Structure and magnetic properties of N-containing Pr–Fe–B alloys prepared by mechanical alloying

Abstract The structure and magnetic properties of Pr 16 Fe 84− x B x N z ( x =0, 2, 4, 6, 8, 10) and Pr y Fe 92− y B 8 N z ( y =20, 25, 30) alloys prepared by mechanical alloying using pyrolytic boron nitride (p-BN) as one of starting materials have been investigated. It is found that with increasing the content of p-BN, the magnetic phase transforms from ferromagnetic Pr 2 Fe 17 - to Pr 2 Fe 14 B-type phase, and finally to paramagnetic Pr 1.1 Fe 4 B 4 -type one. When the Pr 2 Fe 17 - and Pr 2 Fe 14 B-type phases coexist, the nitrogen atoms occupy interstitial sites more preferentially in the Pr 2 Fe 14 B-type phase than in the Pr 2 Fe 17 -type one. Curie temperature of Pr 2 Fe 14 BN δ phase is about 35 K higher than that of Pr 2 Fe 14 B phase, which originates from the occupation of nitrogen atoms in the interstitial sites of the Pr 2 Fe 14 B lattice. A coercivity as high as 23.5 kOe has been achieved for N-containing Pr–Fe–B alloys with y =25.