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Transformation enabled nitride magnets absent rare earths and a process of making the same

A technology of nitride and austenite, which is applied in the field of producing the powder, can solve the problem of not realizing the complete transformation of the powder

Active Publication Date: 2017-10-17
CASE WESTERN RESERVE UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, when conventional diffusion techniques are used to process bulk powders or thin films, equilibrium thermodynamics limits the available nitrogen to <10.3at%N
Thus, complete transformation of these powders has never been achieved even with nanoscale starting powders in the reported literature

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  • Transformation enabled nitride magnets absent rare earths and a process of making the same
  • Transformation enabled nitride magnets absent rare earths and a process of making the same

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Embodiment Construction

[0015] The present invention relates to a method and composition in which rare earth elements are eliminated from permanent magnet materials. Specifically, a large amount of powder is transformed into α”-Fe16N 2 , an ordered martensite. This is achieved by a novel method that enables: the dissolution of more nitrogen in austenitic iron-based alloys than is possible in elemental Fe, the nitrogen-enriched austenitic body into martensite (α'), and finally by tempering martensite into ordered α"-Fe16N2. In austenitic iron-based alloys, dissolution can have a metal:nitrogen ratio of 16:2 .

[0016] Microalloying is used to enlarge the single-phase austenite (γ-Fe) region in the Fe-N phase diagram. This makes the nitrogen concentration necessary to produce intermediate martensite with an optimal stoichiometric composition. Subsequent low-temperature aging heat treatment will complete the transformation to α"-Fe16N2.

[0017] The method of making an ordered martensitic iron nitr...

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Abstract

The invention relates to transformation enabled nitride magnets absent rare earths and a process of making the sam. A process for producing an ordered martensitic iron nitride powder that is suitable for use as a permanent magnetic material is provided. The process includes fabricating an iron alloy powder having a desired composition and uniformity; nitriding the iron alloy powder by contacting the material with a nitrogen source in a fluidized bed reactor to produce a nitride iron powder; transforming the nitride iron powder to a disordered martensitic phase; annealing the disordered martensitic phase to an ordered martensitic phase; and separating the ordered martensitic phase from the iron nitride powder to yield an ordered martensitic iron nitride powder.

Description

[0001] This application is a divisional application of an invention patent application with an application date of December 17, 2012, an application number of 201280069689.2, and an invention title of "Rare Earth-Free Transformable Nitride Magnet and Its Manufacturing Method". [0002] This application claims the benefit of US Provisional Application 61 / 570955, filed December 15, 2011, which is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein. technical field [0003] The present invention generally relates to a composition of iron nitride magnetic powder suitable for permanent magnet applications such as wind turbine generators, electric vehicle motors, etc. and a method of producing the powder. Background technique [0004] Rare earth magnets are strong permanent magnets made from alloys of rare earth elements. Rare earth magnets have significant performance advantages over ferrite or alnico magnets. There are two types of rar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B21/06H01F1/11H01F41/00
CPCC01B21/0622H01F1/11H01F41/00C01P2006/42C01P2006/11C01P2002/54B22F9/082C04B35/58042C04B35/62615C04B35/6265C04B35/6268C22C33/0264C04B2235/405C04B2235/46C04B2235/465H01F1/065H01F1/083C23C8/62H01F1/24H01F41/0266
Inventor 戴维·马太哈斯恩
Owner CASE WESTERN RESERVE UNIV