Grain boundary modification in Fe-rich Sm(CoFeCuZr)z magnets upon Sm71Cu29 addition

The addition of iron content in Sm-Co magnets is beneficial for both the improvement of magnetic properties and the reduction of raw material costs. However, studies on Fe-rich Sm(CoFeCuZr) _z magnets show that Cu-lean phenomenon at grain boundaries leads to the decrease of coercivity and squareness. In order to improve the element distribution, adding Sm ₇₁Cu ₂₉ low melting point eutectic alloy is an effective method. The results show that it can improve the Cu-lean phenomenon at grain boundaries, and it makes the distribution of elements near the grain boundaries more uniform. When the addition amount reaches 0.5 wt%, the micro-scale element distribution of the magnet is improved, which in turn leads to a wider cell boundary phase and larger values of domain-wall energy differences in the nanoscale cellular structure. MOKE microscopy finds that the Sm ₇₁Cu ₂₉-added magnets at the thermal demagnetization state have finer magnetic domains, and the grain boundaries of Sm ₇₁Cu ₂₉-added magnets have stronger pinning ability during the demagnetization process, contributing to high coercivity. The magnet has high comprehensive magnetic properties when adding 0.5 wt%: B _r = 12.02 kG, H _cj = 21.69 kOe, ( BH) _max = 33.05 MGOe.