Effect of Pr on the Structure and Magnetic Properties of CoPt Alloys

The effects of Dy on the microstructure and magnetic properties of Dy x Co50−x Pt50 alloys were investigated. The XRD results indicate that all the alloys homogenized at 1000 °C contain only a single A1 (fcc) phase, while the alloys annealed at 675 °C consist of a hard-magnetic face-centered-tetragonal (fct) phase and a magnetically soft face-centered-cube (fcc) phase. Maximum values for the coercivity H c and remanence ratio m r were achieved in Dy0.4Co49.6Pt50 alloys annealed at 675 °C for 80 min. For the series of Dy x Co50−x Pt50 alloys annealed at 675 °C for 60 min, H c decreases monotonically with increasing Dy concentration, but m r is first enhanced and then weakened.