Sm-Co Magnet Phase Architecture for Coercive Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sm-Co magnets with high Fe concentration face challenges in achieving both high coercive force and magnetization due to decreased coercive force and saturation magnetization, respectively, making it difficult to meet the demands for heat-resistant permanent magnets in hybrid electric and electric vehicle motors.
Innovation Solution
A permanent magnet composition with a specific formula (R p Fe q M r Cu s Co 100-p-q-r-s) and a metallic structure featuring a Th 2 Zn 17 crystal phase, a cell wall phase, and a platelet phase, where R includes rare earth elements like Sm, and a controlled platelet phase thickness of 3-15 nm, is developed to enhance coercive force and magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Fe concentration is increased in Sm-Co magnets to increase magnetization, then saturation magnetization is improved, but coercive force decreases
Solution Approach 1:
The patent applies local quality by creating distinct phases with different compositions and functions: a Th2Zn17-type cell phase providing high magnetization, cell wall phases with specific R-rich compositions providing coercivity, and platelet phases enhancing thermal stability. Each phase is optimized locally to contribute its specific property to the overall magnet performance.
Solution Approach 2:
The patent creates a composite microstructure consisting of multiple phases (Th2Zn17-type cell phase, cell wall phases, and platelet phases) with different compositions and functions. This composite structure allows the magnet to simultaneously achieve high saturation magnetization from the cell phase and high coercive force from the cell wall and platelet phases.
2Temperature
If Dy is used to increase heat resistance of Nd-Fe-B magnets, then operating characteristics at high temperatures are improved, but cost increases due to Dy being a rare element
Solution Approach 1:
The patent merges the advantages of Sm-Co magnets (high Curie temperature and heat resistance) with the high magnetization capability of Nd-Fe-B magnets by creating a composite microstructure that incorporates both Th2Zn17-type phase (providing thermal stability) and R-rich phases (providing magnetic properties), thereby achieving heat resistance without requiring Dy.
Solution Approach 2:
The patent changes the microstructural parameters by controlling phase distribution, cell size, platelet thickness, and composition ratios during solidification and heat treatment processes. These parameter changes enable the magnet to achieve high coercive force and heat resistance through optimized phase architecture rather than relying on Dy addition.
3Force
If a complex multi-phase microstructure is created to achieve high coercive force and magnetization, then magnetic performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by designing an alloy composition that naturally forms the desired multi-phase microstructure during controlled solidification and heat treatment. The specific composition ranges and thermal processing parameters are predetermined to guide the formation of Th2Zn17-type cell phases, cell wall phases, and platelet phases in the correct sequence and distribution, reducing the need for post-processing adjustments.
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 solution achieves coercive force of 650 kA/m or more and residual magnetization of 1.15 T or more, effectively addressing the limitations of Sm-Co magnets with high Fe concentration by optimizing the phase separation structure and composition.
Implementation Method 1
permanent magnet including a composition represented by the following composition formula: R p Fe q M r Cu s Co 100-p-q-r-s (atomic %)... a metallic structure including a cell phase, a cell wall phase, and a platelet phase... coercive force of the permanent magnet is 650 kA/m or more, and a residual magnetization of the permanent magnet is 1.15 T or more
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
In one embodiment, a permanent magnet has a composition represented by a composition formula: RpFeqMrCusCo100-p-q-r-s, where R is a rare earth element, M is at least one element selected from Zr, Ti, and Hf, p is 8.0 atomic% or more and 13.5 atomic% or less, q is 25 atomic% or more and 40 atomic% or less, r is 0.88 atomic% or more and 7.2 atomic% or less, and s is 3.5 atomic% or more and 13.5 atomic% or less, and a metallic structure including a cell phase having a Th2Zn17 crystal phase, a cell wall phase, and a platelet phase existing along a c plane of the Th2Zn17 crystal phase. An average thickness of the platelet phase is in a range of from 2.5 nm to 20 nm.