Origin of anisotropy in the HDDR process of Nd[sub 2]Fe[sub 14]B-based alloys

Conference · Mon Nov 01 04:00:00 EST 1993 · IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States)

OSTI ID:6822685

Uehara, M; Tomizawa, H; Hirosawa, S ^[1]; Tomida, T; Maehara, Y ^[2]

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1. Sumitomo Special Metals Co., Ltd., Osaka (Japan)
2. Sumitomo Metal Industries, Ltd., Amagasaki (Japan)

To clarify the origin of magnetic anisotropy induced in Nd[sub 2]Fe[sub 14]B-based magnet powders during hydrogenation, disproportionation, desorption, and recombination (HDDR) process, the authors have investigated the microstructures of hydrogenated Nd[sub 12.5]Fe[sub 70[minus]x]Co[sub 11.5]Ga[sub x]B[sub 6] powders (0[le]x[le]5). As the hydrogenation temperature was increased over 1,148 K, a small amount of Nd[sub 2]Fe[sub 14]B phase was observed to remain undecomposed in the Nd[sub 12.5]Fe[sub 69]Co[sub 11.5]Ga[sub 1]B[sub 6] powder even after the hydrogenation for 3.6 ks. This undecomposition became more evident when Increasing the temperature up to 1,198 K. The size of the undecomposed Nd[sub 2] Fe[sub 14] B particles In the powder hydrogenated at 1,148 K was about 0.3 [mu] m. The powder with the undecomposed Nd[sub 2]Fe[sub 14]B exhibited the magnetic anisotropy after the subsequent desorption process at 1,123 K. The Increase of the amount of Ga content, which is known to be an essential additive for the anisotropy Induction, also decelerated the decomposition. The origin of the anisotropy could therefore be the finely dispersed undecomposed Nd[sub 2]Fe[sub 14]B particles, which can be formed under the controlled hydrogenation condition and with the additives to decelerate the decomposition. Such dispersed particles should act as nuclei for a growth or recrystallization of the Nd[sub 2]Fe[sub 14]B phase, during the desorption process, with the preferred orientation, i.e., the orientation of original Nd[sub 2]Fe[sub 14]B phase.

• OSTI ID: 6822685
• Report Number(s): CONF-930416--
• Conference Information: Journal Name: IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States) Journal Volume: 29:6Pt1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
BORON ALLOYS
CHEMICAL REACTIONS
COBALT ALLOYS
DATA
EXPERIMENTAL DATA
FABRICATION
GALLIUM ALLOYS
HYDROGENATION
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MAGNETIC MATERIALS
MAGNETIC PROPERTIES
MATERIALS
MICROSTRUCTURE
NEODYMIUM ALLOYS
NUMERICAL DATA
PHASE STUDIES
PHYSICAL PROPERTIES
RARE EARTH ALLOYS