Optimization of magnetic properties of sintered (SmGdDy)(Co, Fe, Cu, Zr)z magnets by Dy–Co addition

Abstract Liquid phase sintering is used to optimize the magnetic properties and temperature stability of (SmGdDy)(Co, Fe, Cu, Zr) z sintered magnet. DyCo 0.51 and Sm 0.67 Dy 0.11 Gd 0.22 (Co 0.693 Fe 0.201 Cu 0.081 Zr 0.0252 ) 7.94 alloys are chosen as liquid phase and main phase, respectively. (SmGdDy)(Co, Fe, Cu, Zr) z permanent magnets are prepared with different content of liquid phase. XRD analysis shows that all magnets consist of Th 2 Zn 17 -type phase and CaCu 5 -type phase. Cellular structure studies indicate that the H1-5 cell boundary phase shifts gradually from thin and part of discontinuous to thick and continuous. The cell size decreases with the increase of the content of liquid phase. In addition, the Cu content in cell boundary phase is getting lower with the increase of LP adding ratio. The homogeneous and continuous cellular structure is got when the adding ratio of liquid phase is 3 wt% and the highest intrinsic coercivity is achieved at room temperature (23.88 kOe) and 200 °C (12.06 kOe). It’s interesting to find that temperature dependence of remanence ( α ) and the temperature dependence of intrinsic coercivity ( β ) can be optimized with the increase of the content of liquid phase, in which the α (20–100 °C) and β (20–200 °C) are −0.0075%/°C and −0.140%/°C for the magnet with 5 wt% liquid phase, and −0.016%/°C and −0.322%/°C for the magnet with 1 wt% liquid phase.