MAGNETIC DOMAIN-STRUCTURE OF ANISOTROPIC ND2FE14B-BASED MAGNETS PRODUCED VIA THE HYDROGENATION, DECOMPOSITION, DESORPTION AND RECOMBINATION(HDDR) PROCESS

Lorentz transmission electron microscopy and optical Kerr microscopy s tudies of the hydrogenation, decomposition, desorption and recombinati on (HDDR)-processed anisotropic Nd2Fe14B-based magnets show that a mag netic domain structure develops in which a unit domain includes a numb er of submicron Nd2Fe14B grains coupled by the intergrain-ex change in teraction. Grain boundaries and particles of an intergranular phase ha ve been observed to pin the domain boundary walls, and their magnetic characteristics and distribution may determine the size of magnetic do mains forming in a thermally demagnetized state, Measurements of diffe rential susceptibilities indicate that the motions of the domain walls become sluggish after magnetization and de-field demagnetization, com pared to that in a thermally demagnetized state.