MAGNETIC-PROPERTIES AND MICROSTRUCTURE IN NDDYFEBZR-HDDR

Cast alloys with a range of compositions based on Nd1.5Fe77B8 with add itions of Dy and Zr were produced by a conventional casting method. Zr was added prior to casting in the form of either zirconium or zirconi a. The materials were processed using the hydrogen decrepitation, disp roportionation, recombination (HDDR) technique in order to develop the fine microstructures necessary for high coercivities. Magnetic measur ements on bonded samples produced from the HDDR powders indicated that additions of Zr tended not to affect the recombination temperatures a t which the material began to develop high coercivity, but was clearly observed to extend the temperature range over which high coercivity m aterial could be produced. Microstructural analysis revealed that the Zr-doped samples were less prone to the explosive grain growth exhibit ed by the Zr-free samples at these temperatures. (C) 1998 Elsevier Sci ence B.V. All rights reserved.