Sm-Fe Magnet Raw Material Phase Control
Solution Overview
Problem
Rare earth magnets that do not use dysprosium are needed to address the instability in dysprosium prices and limited production areas, while maintaining high magnetic flux density and coercive force.
Innovation Solution
A raw material comprising an Sm-Fe binary alloy with a high proportion of the SmFe7 phase, produced through a hydrogenation/dehydrogenation decomposition reaction and recombination process, followed by nitriding, to achieve superior magnetic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dysprosium is added to strengthen heat resistance and coercive force, then magnetic performance is improved, but material cost increases and supply stability deteriorates
Solution Approach 1:
The invention extracts and eliminates dysprosium from the magnet composition, replacing it with an Sm-Fe binary alloy system. By removing the problematic rare earth element (dysprosium) while retaining the essential magnetic properties through optimized Sm-Fe phase composition, the patent resolves the contradiction between maintaining coercive force and reducing dependency on scarce, expensive materials.
Solution Approach 2:
The invention changes the compositional parameters from a multi-element system containing dysprosium to a binary Sm-Fe system with specific phase ratios. By controlling the SmFe7 phase proportion to 50-90% and adjusting the Sm/Fe atomic ratio, the patent achieves high coercive force and heat resistance without dysprosium, thus resolving the material availability and cost issue.
2Reliability
If Sm-Fe binary alloy with high SmFe7 phase proportion is used, then magnetic flux density and Curie temperature are improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies preliminary hydrogenation to the Sm-Fe alloy before final magnet production. By performing hydrogen absorption and decomposition reactions in advance to form the desired SmFe7 phase structure, the patent simplifies subsequent manufacturing steps while ensuring the raw material has the optimal phase composition for high magnetic flux density and Curie temperature.
Solution Approach 2:
The invention utilizes phase transitions during hydrogenation and heat treatment to transform the Sm-Fe alloy into the desired SmFe7 dominant phase structure. By controlling temperature and hydrogen pressure during these transitions, the patent achieves the target phase composition without requiring complex manufacturing processes, thus resolving the contradiction between performance and manufacturing simplicity.
3Quantity of substance
If conventional Sm-Fe-N magnet composition is used, then rare earth content is reduced, but coercive force degradation occurs during use
Solution Approach 1:
The invention creates a composite magnetic material system based on Sm-Fe binary alloy with dominant SmFe7 phase, combined with nitrogen incorporation. This composite approach achieves high coercive force and heat resistance with reduced rare earth content by optimizing the phase composition and utilizing the synergistic effects of SmFe7 phase and nitrogen, thus resolving the contradiction between rare earth reduction and coercive force stability.
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 resulting magnet exhibits high magnetic flux density and Curie temperature, with a high ratio of the SmFe7 phase, enhancing magnetic performance and reducing coercive force degradation.
Implementation Method 1
subjecting a powdered base material for the raw material for a magnet, which is obtained by melting a mixture of samarium and iron, to a decomposition reaction by absorbing hydrogen and a recombination reaction by releasing hydrogen
Implementation Method 2
the recombination reaction is carried out at 600° C. or higher and 675° C. or lower
Implementation Method 3
a raw material for a magnet which is possible to obtain a magnet having superior magnetic characteristics by nitriding
Data Source
AI summary
A raw material for a magnet, which comprises Sm and Fe. A magnet is obtained by nitriding this raw material for a magnet. In particular, a raw material for a magnet comprises an Sm—Fe binary alloy as a main component. An intensity ratio of an Sm2Fe17 (024) peak to an SmFe7 (110) peak is less than 0.001 as measured by an X-ray diffraction method.