Magnetic properties and microstructures of mischmetal-FeB-(Al, Ti and Al-Co) permanent magnets

The magnetic characteristics of anisotropic MM-FeB- (Al, Ti and Al-Co) permanent magnets have been investigated by using hot-pressing and die-upsetting process. The best magnetic properties obtained in these studies were H-C = 5.1 kOe, B-r = 5.4 kG with (BH)(max) = 5.1 MGOe for hot-pressed MM-FeB-Al-Co magnets and H-C = 3.6 kOe, B-r = 6.7 kG, (BH)(max) = 6.8 MGOe for die-upset MM-FeB-Al-Co magnets. Higher squareness of demagnetization curve was obtained in anisotropic die-upset MM-FeB- (Al, Al-Co) magnets. X-ray diffraction and STEM investigations revealed that the higher magnetic properties in die-upset magnets were resulted from alignment of the c-axis along the die-upsetting direction. The magnetic anisotropy of the die-upset magnets and the densification of the hot-pressed magnets were increased by partial substitution of Al and Al-Co for Fe. (C) 2002 Kluwer Academic Publishers.