Development of anisotropic die upset magnets with high energy product by some organic materials

To improve the magnetic properties and hot workability of anisotropic Nd-Fe-Co-B-Ga die upset magnets, the effects of inner lubricants were studied. BN, MoS₂, and graphite powder were employed as inner lubricants. Additions of small amounts of graphite powder were the most effective lubricant among the three types of inorganic agents. By employing liquid lubricants instead of inorganic solid lubricants, further improvement in magnetic properties and in the ability to flow when hot were achieved. Die upset magnets with 0.3 wt.% oleic acid showed 4πIr=12.6 kG, iH_c=15.7 kOe, and (BH)_max=38.5 MG-Oe. The increase in energy product was 7 MG-Oe compared with unlubricated magnets. X-ray diffraction revealed that the improvement was caused by better crystal alignment along the compression direction during plastic flow. Inner lubricants were found to work effectively as grain growth inhibitors in flake interfaces during hot working