COMBINED EFFECTS OF AL AND CO ADDITIONS ON THE MAGNETIC-PROPERTIES OFFE-ND-B SINTERED MAGNETS

The magnetic properties of sintered Fe-Nd-B magnets containing minor a dditions of either Al or Co or both Al and Co were studied. It was fou nd that the magnets containing Al and Co exhibit substantially higher coercivities than those with additions of only Al or Co. The highest c oercivity of 1380 kA/m was achieved for the composition Fe72Nd18.5B6.5 CO3 + (3-5) at % Al. The corresponding Curie temperature was approxima te to 330 degrees C which was much higher than that for the alloy cont aining Al only. We attribute the improved coercivity for the alloys co ntaining Al and Co, when compared with the quaternary alloys, to a red uced proportion of the soft magnetic inclusions in the grain boundary area.