MAGNETIC-PROPERTIES AND MICROSTRUCTURAL ANALYSIS OF RAPIDLY QUENCHED FENDBGANB PERMANENT-MAGNETS

The magnetic properties and the microstructure of rapidly quenched FeN dBGaNb magnets have been investigated. The grain size distribution was varied by changing the quenching rates and applying different anneali ng treatments. From the initial magnetization curves the fractions of single domain and multidomain particles were determined in differently quenched magnets. In order to optimize the magnetic properties severa l annealing treatments were carried out. From the temperature dependen ce of the critical field the microstructural parameters alpha(K) und N -eff were determined. These parameters describe the effect of a non-id eal microstructure, i.e. magnetically imperfect grain surfaces and int ernal stray fields, on the magnetic properties of the magnet. The micr ostructures of several as-quenched and annealed magnets were investiga ted using TEM technique.