INFLUENCE OF SUBSTITUTION OF CR FOR FE ON MAGNETIC-PROPERTIES OF ND4FE77.5B18.5 ALLOYS

The room-temperature hysteresis loops and phase components of Nd4(Fe1-xCrx)77.5B18.5 (0 less-than-or-equal-to x less-than-or-equal-to 0.25) alloys were measured. The influence of Cr on the magnetic properties and structure was studied. The substitution of Cr for Fe results in a change of the phase components. The alloys with x less-than-or-equal-to 0.1 consist of Fe3B and alpha-Fe phases. When x > 0.1 the alloys consist of alpha-Fe, Nd2Fe14B and Fe2B phases. For the alloys with Cr content x less-than-or-equal-to 0.1 the magnetization and coercivity decrease with increasing Cr content. However the magnetization and coercivity of the alloys with x > 0.1 increase, as the Cr content is increased. It is found that the substitution of Cr for Fe can result in a great increase of the coercivity from 3 kOe for Nd4Fe77.5Bi18.5 to 4.9 kOe for Nd4(Fe0.75Cr0.25)77.5B18.5 alloys.