Abstract
The chemical composition dependence of properties of high-Co–Fe–Nb semihard magnetic alloys was investigated. Magnetic properties, resistivity, Vickers hardness, X-ray diffraction and thermal expansion coefficient were measured in the specimens annealed at 500∼1100°C after cold drawing by 90% reduction in area. The coercive force (Hc) of the specimen containing more than 2 wt% Nb was remarkably increased by annealing near 700°C and the value of the alloy with 4 wt% Nb reached about 30 Oe. Moreover, a squareness ratio (Ir⁄I100) higher than 0.90 and magnetization (4πI100) about 16000 G were achieved. The values of squareness ratio and remanence of specimens containing more than 15 wt% Fe in the cold drawn state were low. However, the values increased with annealing temperature and reached over 0.90 and 14500 G by 700°C annealing, respectively. The crystal structure of Co-21 wt% Fe-3 wt% Nb alloy in the cold-drawn state was bcc and transformed into the fcc phase by annealing above 900°C.
