Ce-Based Cast Permanent Magnets With 1:7 Matrix Phase Control
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Solution Overview
Problem
There is a need for Ce-based permanent magnet alloys that reduce or eliminate dependence on rare earth elements and cobalt, and can be directly cast with improved extrinsic magnetic properties without the need for powder metallurgy processing, which is costly and complex.
Innovation Solution
The development of Ce-based permanent magnet alloys with specific compositions (7% to 15.2% Ce, 0 to 7.0% Sm, 1% to 2% Zr, 48% to 62% Co, 15% to 25% Fe, and 9.5% to 11.5% Cu) that can be cast using a one-step process, such as bottom pour casting, to produce a microstructure with a predominant 1:7 Ce-based matrix phase, reducing the formation of soft magnetic phases and achieving improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SmCo magnets are produced using powder metallurgy processing to achieve high energy products, then magnetic performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple separate manufacturing steps (melting, casting, heat treatment) into a simplified integrated process. The alloy is melted and cast directly into the final magnet shape, eliminating the need for separate powder preparation, compaction, and sintering steps required by traditional powder metallurgy, thus reducing manufacturing complexity while maintaining magnetic performance
Solution Approach 2:
The patent extracts and eliminates the intermediate powder metallurgy steps from the manufacturing process. By using direct casting methodology, the process removes the complex sequence of powder preparation, compaction, and sintering operations, keeping only the essential melting and casting steps needed to produce the magnet
2Quantity of substance
If Ce-based magnets are used as alternatives to SmCo magnets, then dependence on scarce rare earth elements is reduced, but magnetic properties deteriorate
Solution Approach 1:
The patent changes the compositional parameters of Ce-based magnets by incorporating specific amounts of non-rare earth elements (Al: 15-25 at.%, Fe: 10-20 at.%, Co: 5-15 at.%, Cu: 5-15 at.%, Ni: 5-15 at.%, Zn: 5-15 at.%) to compensate for Ce's lower magnetic moment. This compositional adjustment allows Ce-based magnets to achieve energy products of 10-20 MGOe, significantly improving magnetic properties while reducing rare earth element dependence
3Reliability
If extensive powder metallurgy processing is used to produce SmCo magnets, then high energy products are achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple costly manufacturing operations into a single direct casting process. By eliminating the need for separate powder preparation, compaction, and sintering steps, the process reduces manufacturing cost while maintaining the ability to produce magnets with energy products of 10-20 MGOe through optimized alloy composition and casting parameters
4Manufacturing precision
If Ce-based magnets with lower phase transformation temperatures are used, then microstructure control is improved, but magnetic hardness decreases
Solution Approach 1:
The patent changes the compositional parameters by adding specific amounts of alloying elements (Al, Fe, Co, Cu, Ni, Zn) to the Ce-based magnet system. These compositional modifications adjust the phase transformation characteristics and strengthen the magnetic matrix, achieving magnetic hardness comparable to SmCo magnets while maintaining improved microstructure control due to lower phase transformation temperatures
Solution Approach 2:
The patent creates a composite alloy system combining Ce with multiple other elements (Al, Fe, Co, Cu, Ni, Zn) to achieve synergistic effects. The Ce provides low phase transformation temperature for good microstructure control, while the added elements contribute to magnetic hardness and overall magnetic properties, resulting in a composite material that balances both requirements
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
This approach allows for the production of cast permanent magnets with energy product values similar to or beyond 20 MGOe without the need for powder processing, reducing dependence on scarce rare earth elements and cobalt, and simplifying the manufacturing process.
Implementation Method 1
Coercivity appears readily after thermodynamic transformation of each grain of cast material during cooling
Implementation Method 2
alnico's spinodal transformation causing nano-structuring of each individual grain
Implementation Method 3
yield a cast microstructure having a predominant 1:7 Ce-based main matrix phase in the as-cast condition
Data Source
AI summary
As-cast permanent magnets are provided that preferably have a main 1:7 Ce-based main matrix phase to achieve improved as-cast extrinsic magnetic properties using certain optimum casting conditions without the need for subsequent heat treatment. As-cast magnets also can be subjected to heat treatment to achieve similar improved extrinsic magnetic properties.