Effect of magnetic field and boron addition on the structural and magnetic properties of the rapidly solidified Fe₆₀Nd₃₅Al₅ master alloys magnet by suction casting

Ingots with nominal composition (Nd₀.₆₀Fe₀.₃₅Al₀.₀₅)100-x Bx with x=2 were produced by arc-melting of elemental Nd, Al, B and Fe-B alloy with the purity of 99.9% under argon atmosphere. Specimen (dimension: 35×10×10 mm3) were prepared by suction casting into a copper mold. An influence of the annealing with and without applied magnetic field of a 140 Oe in a furnace with a vacuum of 2×10-4 Pa at 823 K function of annealing time, process was investigated in B-doped Nd-Fe-Al rapidly solidified magnets. The microstructure, structural properties and magnetic domains of the Fe-Nd-Al alloys prepared by suction casting with boron addition have been investigated. The increasing of the annealing time of the sample significantly increases the intrinsic coercivity (iHc) and decreases the proportion of the amorphous phase. The magnetization at the maximum applied field (σs) of the Fe-Nd-Al-B alloys decreases, while the coercivity increases markedly after annealing. The high intrinsic coercivity is due to the presence of the Nd2Fe14B phase. This can be confirmed by the structural, magnetic properties and microstructure using DSC, XRD, VSM, SEM and optical microscopy, in addition the magnetic domains by AFM-MFM.