FRACTURE-TOUGHNESS OF ND2FE14B MAGNETS

Nd2Fe14B is currently the best (highest energy product) hard magnet av ailable. Like most magnetic materials, it is rather brittle. The fract ure toughness of specimens of commercially available hard magnets were measured using a chevron notch, three-point bend test. Values for Nd2 Fe14B magnets ranged from 2.5 to 5.5 MPa root m. In comparison, SmCo5 was measured to have a fracture toughness of 1.9 MPa root m. It appear s that this testing technique will allow differences in fracture tough ness to be measured between alloys with different compositions and fab ricated by different production methods and should be able to track th e fracture toughness as improvements are made to a particular alloy.