Effect of Mn Doping on Magnetic Properties, Magnetic Domain Structures, and Microstructures of 2–17 Type Sm–Co Magnets

Magnetic properties, magnetic domain structures, and microstructures of Sm(Fe0.328Cu0.055Zr0.017MnxCobal)7.65 (
$x$
= 0.005 and 0.010) were investigated. Even with Mn content increased, magnetic properties did not deteriorate, remanent magnetic flux density,
$B_{r}$
, maximum energy product,
$[BH]_{m}$
, and squareness,
$H_{k} / H_{cj}$
(
$H_{k}$
is a reverse magnetic field value when magnetization becomes 90% of
$B_{r}$
), exceeded 12 kG, 33.5 MGOe, and 70%, respectively, in both samples. However, a mechanism of magnetic reversal was different; reverse magnetic domains were easy to propagate from grain boundaries in
$x$
= 0.005 and grain interior in
$x$
= 0.010, respectively. In microstructures, Cu concentration increased in grain boundaries, and cell size enlarged with an increase in Mn content. Because microstructures were formed properly and its size was enlarged, which produce a strong pinning force, and negative effects of doping non-ferromagnetic element Mn were compensated.