NdFeB Auxiliary Alloy Composition for Heavy Rare Earth-Free Coercivity
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Solution Overview
Problem
The high cost and scarcity of heavy rare earth elements dysprosium and terbium in high-performance sintered NdFeB permanent magnets necessitate the development of a high-remanence and high-coercive force NdFeB permanent magnet without these elements, while existing technologies lack effective methods for regulating the microstructure to achieve such performance.
Innovation Solution
A method involving the preparation of an auxiliary alloy casting piece with specific compositions and processing techniques, including smelting, quick-setting casting, and double-alloy hydrogen decrepitation, jet milling, orientation molding, sintering, and tempering, to produce a high-remanence and high-coercive force NdFeB permanent magnet, utilizing titanium and vanadium to refine grains and optimize the distribution of rare earth-rich phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements dysprosium or terbium are used in sintered NdFeB permanent magnets, then coercive force and magnetic performance are improved, but production cost increases significantly
Solution Approach 1:
The patent replaces expensive heavy rare earth elements (dysprosium and terbium) with lighter, cheaper rare earth elements (praseodymium and neodymium) in the auxiliary alloy composition. This substitution maintains the necessary magnetic performance while significantly reducing raw material costs, directly addressing the contradiction between coercive force and production cost
Solution Approach 2:
The patent optimizes the compositional parameters of the auxiliary alloy, specifically controlling the content of praseodymium (40-45%), cobalt (1-2%), gallium (0.5-1%), and other elements within precise ranges. This parameter optimization enables achieving high coercive force without heavy rare earth elements, resolving the cost-performance contradiction
2Reliability
If the microstructure of auxiliary alloy is not properly regulated, then high-performance sintered NdFeB permanent magnets without heavy rare earth elements cannot be achieved, but microstructure regulation methods are insufficient
Solution Approach 1:
The patent performs preliminary microstructure regulation by controlling the casting process parameters (casting temperature 1330-1380°C, copper roller rotational speed 60-80 rpm) to produce auxiliary alloy casting pieces with spherical microstructures before the main sintering process. This preliminary action ensures the desired microstructure is achieved without complex in-situ regulation during sintering
Solution Approach 2:
The patent systematically optimizes multiple process parameters including smelting temperature (1390-1430°C), refining temperature (1460-1510°C), casting temperature (1330-1380°C), cooling rate (7-15°C/min), and alloy composition ratios. This comprehensive parameter optimization enables precise microstructure control, achieving high magnetic performance through regulated spherical microstructures
3Shape
If quick-setting casting with controlled cooling rate is used, then spherical microstructures are formed in auxiliary alloy, but processing time and temperature control requirements increase
Solution Approach 1:
The patent optimizes the cooling rate parameter within a specific range (7-15°C/min) to achieve spherical microstructures in the auxiliary alloy casting piece. This parameter optimization balances the formation of desired spherical microstructures with reasonable processing time, avoiding excessively slow cooling that would prolong production
Solution Approach 2:
The patent utilizes controlled phase transition during the quick-setting casting process, where the molten auxiliary alloy is cooled at a controlled rate (7-15°C/min) from casting temperature (1330-1380°C) to form spherical microstructures. This phase transition control enables microstructure regulation while maintaining efficient processing
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 enables the production of high-performance NdFeB permanent magnets without dysprosium or terbium, achieving remanence of 14.3 kGs and coercive force of 17 kOe, while conserving rare earth resources and reducing production costs, with the method being suitable for mass production and ensuring product stability.
Implementation Method 1
smelting the auxiliary alloy material to obtain a smelted material
Implementation Method 2
the cooling is conducted by argon-filled air cooling at a cooling rate of 7° C./min to 15° C./min
Implementation Method 3
subjecting the main alloy casting piece and the auxiliary alloy casting piece to a double-alloy hydrogen decrepitation
Implementation Method 4
subjecting the main alloy casting piece and the auxiliary alloy casting piece to a double-alloy hydrogen decrepitation, a jet milling, an orientation molding, a sintering, and a tempering in sequence
Implementation Method 5
subjecting the main alloy casting piece and the auxiliary alloy casting piece to a double-alloy hydrogen decrepitation, a jet milling, an orientation molding, a sintering, and a tempering in sequence
Data Source
AI summary
Provided are an auxiliary alloy casting piece, a high-remanence and high-coercive force NdFeB permanent magnet, and preparation methods thereof. The method for preparing the auxiliary alloy casting piece includes the following steps: providing an auxiliary alloy material including, by mass percentage, 40% to 45% of Pr, 1% to 2% of Co, 0.5% to 1% of Ga, 0.6% to 0.8% of B, 0.1% to 0.2% of V, 0.3% to 0.7% of Ti, and a balance of Fe; smelting the auxiliary alloy material to obtain a smelted material; and subjecting the smelted material to a quick-setting casting to obtain the auxiliary alloy casting piece; where the quick-setting casting includes a refining and a casting in sequence.