Fe16N2 Permanent Magnet Formation Without Rare Earths
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Solution Overview
Problem
Current permanent magnets rely heavily on rare earth elements, which are in short supply and expensive, and their production processes are energy-intensive.
Innovation Solution
Development of bulk Fe16N2 permanent magnets formed by straining iron wire or sheet along the crystal axis, introducing nitrogen, and annealing to create a Fe16N2 phase constitution, which can be assembled into larger magnets with controlled magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements (neodymium) are used in permanent magnets, then magnetic performance is improved, but cost and supply reliability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by replacing rare earth elements with abundant iron and nitrogen, specifically forming Fe16N2 phase with controlled nitrogen content (at least 5 atomic percent) to achieve high magnetic performance without relying on neodymium or other rare earth elements
Solution Approach 2:
The patent substitutes expensive rare earth materials with inexpensive, abundant iron and nitrogen materials, making the permanent magnet economically viable and supply-secure while maintaining competitive magnetic performance
2Reliability
If traditional sintering process is used for NdFeB magnets, then magnetic properties are achieved, but energy consumption and manufacturing complexity increase
Solution Approach 1:
The patent changes the processing temperature parameter from traditional sintering temperatures over 1000°C to a lower temperature range of 400-600°C, significantly reducing energy consumption while achieving the desired Fe16N2 phase formation and magnetic properties through controlled nitridation and heat treatment
Solution Approach 2:
The patent replaces the complex multi-step sintering process with a simplified sequence of nitridation followed by low-temperature heat treatment, reducing manufacturing complexity and process steps while achieving comparable or superior magnetic properties
3Quantity of substance
If iron and nitrogen are used instead of rare earth elements, then cost and availability are improved, but magnetic performance may deteriorate
Solution Approach 1:
The patent creates a composite structure at the atomic level by forming Fe16N2 interstitial compound where nitrogen atoms occupy interstitial sites in the iron lattice, achieving enhanced magnetic properties (energy product up to 134 MGOe) that exceed traditional rare earth magnets while using only abundant iron and nitrogen
Solution Approach 2:
The patent introduces localized nitrogen enrichment at specific interstitial positions in the iron lattice to create regions of high magnetic anisotropy and enhanced coercivity, achieving superior magnetic performance through localized compositional control rather than uniform distribution
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Fe16N2 magnets offer high energy products of up to 134 MGOe, providing efficient alternatives for electric motors and generators, and are cost-effective due to the abundance of iron and nitrogen.
Implementation Method 1
straining an iron wire or sheet comprising at least one iron crystal in a direction substantially parallel to a <100> crystal axis of the iron crystal to distort a unit cell structure of the at least one iron crystal
Implementation Method 2
nitridizing the iron wire or sheet to form a nitridized iron wire or sheet
Implementation Method 3
annealing the nitridized iron wire or sheet to order the arrangement of iron and nitrogen atoms and form the Fe16N2 phase constitution
Data Source
AI summary
A permanent magnet may include a Fe16N2 phase constitution. In some examples, the permanent magnet may be formed by a technique that includes straining an iron wire or sheet comprising at least one iron crystal in a direction substantially parallel to a <001> crystal axis of the iron crystal; nitridizing the iron wire or sheet to form a nitridized iron wire or sheet; annealing the nitridized iron wire or sheet to form a Fe16N2 phase constitution in at least a portion of the nitridized iron wire or sheet; and pressing the nitridized iron wires and sheets to form bulk permanent magnet.