Anisotropic Nd-Fe-B resin bonded magnet MAGFINE®Dy Free

Material Technology

Our MAGFINE® (abbreviation MF) NdFeB anisotropic bonded magnets have world leading 25MGOe magnetic force and 150 degree heat resistance. The world’s strongest NdFeB magnets were discovered in 1982 and produced as sintered magnets and isotropic bonded magnets. Isotropic bonded magnets lose their magnetic properties over time, so for twenty years many worked to develop high performance anisotropic magnetic powder. Aichi Steel discovered the manufacturing principles for anisotropic magnetic powder (d-HDDR method) and succeeded in bringing anisotropic bonded magnets to market.

The name MAGFINE® combines “magnet” with “fine”, referring to the fine structure formed using our unique d-HDDR method.

Principles of the d-HDDR method (discovered in 1996)

Controlling the absorption and desorption speed of NdFeB alloy and hydrogen at a certain critical velocity can simultaneously miniaturize crystal grains and turn them anisotropic, resulting in superb magnetic powder.

Discovery of the anisotropic structure mechanism (2003)

In the reaction between the NdFeB alloy and hydrogen, first a 2-phase structure is formed with a lamellar structure of Fe containing supersaturated B and NdH. The ferrous phase has deformation in one direction caused by the lamellar structure and the Fe B phase is observed forming aligned orientation as a crystal to mitigate the deformation (figure on right). In the hydrogen release process, the Fe B phase is recrystallized and the orientation of the crystals is aligned. That is, the Fe B phase functions as a phase with memory of the orientation before the reaction. This unique metallurgical anisotropic mechanism is presented as a TM (texture memory) effect.

Creation of Dy-free MAGFINE® (2011)

Up to this point, precious rare earth elements Dy and Ga were added in order to give the material heat resistance. We successfully created low-cost magnets by diffusing a non-magnetic powder into the grain boundary of the d-HDDR powder with a particulate size of 0.3 micrometers that gave the product a heat resistance of 150℃.

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* “MAGFINE®” is a registered trademark of AICHI STEEL CORPORATION in Japan and other countries.