2013 Volume 54 Issue 10 Pages 2007-2010
This paper describes the influence of heat treatment on the microstructure and magnetic properties of Mn–Sn–Co–N alloys. After homogenization at 950°C for 20 h in Ar, Mn82.5Sn10Co7.5 alloys were annealed at 900°C for 1–20 h in N2 and quenched to room temperature (first-annealing). The alloys were subsequently annealed at 400–700°C for 5 h in N2 and quenched to room temperature (second-annealing). The coercivity of the alloys changed drastically by the second annealing. The samples subjected to second annealing at 500°C showed maximum coercivity of 1270 kAm−1 and exhibited a fine two-phase microstructure. Wavelength Dispersive X-ray Spectrometer (WDS) and X-ray Diffraction (XRD) analyses revealed that the fine two-phase microstructure consists of β-Mn and perovskite-type (Mn4N-like) phases, as well as that the two phases emerged from the ζ′ phase during the second-annealing at 500°C.