DOMAIN STUDIES IN THIN-SECTIONS OF HDDR-PROCESSED ND-FE-B-TYPE MAGNETS BY TEM

Transmission electron microscopy has been used to study the magnetic d omain structure and its evolution under an external applied field in t hin sections of Nd-Fe-B-type magnets produced by the solid-HDDR route, Large aligned regions of submicron grains cause an irregular, periodi c magnetic domain structure, In situ magnetising experiments showed th at domain walls in the centres of grains tended to move until they lea ched grain boundaries where they remained pinned; with higher fields o ccasional jumps from one grain boundary to the nest were observed unti l an applied field was reached that appeared to remove all the domain walls in that region. Under the application of a reverse field, where domain structures were observed, it was rare to find domain boundaries and grain boundaries which did not coincide. (C) 1998 Elsevier Scienc e B.V. All rights reserved.