Double-Main-Phase Ce Permanent Magnet Alloy Design
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Solution Overview
Problem
Current methods for producing Ce permanent magnet alloys result in low magnetic performance and high production costs due to excessive substitution of Nd with Ce, leading to inadequate residual magnetism, coercive force, and magnetic energy product.
Innovation Solution
A low-cost double-main-phase Ce permanent magnet alloy with a chemical formula of (Cex,Re1-x)aFe100-a-b-cBbTMc is developed, featuring a double-main-phase structure with a high HA phase in Nd—Fe—B and a low HA phase in (Ce,Re)—Fe—B, using a preparation method that includes smelting rapid solidified strips, jet milling, and aligned forming under a magnetic field, followed by sintering and tempering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal Ce is added to substitute Nd in Nd2Fe14B, then cost is reduced, but magnetic performance deteriorates
Solution Approach 1:
The patent divides the single-phase structure into two distinct main phases: Nd2Fe14B phase (providing high magnetic performance) and Ce2Fe14B phase (providing cost reduction). This segmentation allows each phase to fulfill its specific function, resolving the contradiction between cost and performance by preventing Ce from excessively substituting Nd in the high-performance phase while still achieving significant cost reduction through the presence of the lower-cost Ce phase.
Solution Approach 2:
The patent creates local quality differentiation by forming distinct regions with different compositions and properties. The Nd2Fe14B phase maintains high magnetic performance characteristics, while the Ce2Fe14B phase provides cost advantages. This local quality approach allows the material to exhibit both high performance in critical regions and cost efficiency in other regions, simultaneously achieving both goals.
2Quantity of substance
If Ce content is increased to reduce cost, then residual magnetism and coercive force decrease
Solution Approach 1:
By segmenting the microstructure into two distinct main phases rather than allowing uniform Ce substitution, the patent enables higher overall Ce content (up to 40-50 at%) without uniformly degrading magnetic parameters. The Nd2Fe14B phase preserves high magnetic performance while the Ce2Fe14B phase accommodates the higher Ce content, thus resolving the contradiction between Ce content and magnetic parameters.
Solution Approach 2:
The patent creates a composite material system with two main phases, each contributing different properties. The Nd2Fe14B phase provides high magnetic performance, while the Ce2Fe14B phase enables higher Ce content incorporation. This composite approach allows the material to achieve both high Ce content for cost reduction and maintained magnetic parameters, resolving the technical contradiction.
3Device complexity
If traditional single alloy method is used, then preparation process is simple, but magnetic performance is insufficient
Solution Approach 1:
The patent segments the preparation process into distinct stages: first preparing Nd-containing alloy, then adding Ce to form the second phase. This segmented approach, while more complex than single-alloy methods, enables precise control over phase formation and composition, thereby achieving the required magnetic performance that simple methods cannot provide.
Solution Approach 2:
The patent applies preliminary action by first forming the Nd2Fe14B phase with appropriate composition and microstructure, then subsequently introducing Ce to form the Ce2Fe14B phase. This preliminary formation of the high-performance phase ensures that magnetic parameters are established before the cost-reducing Ce phase is added, preventing degradation of magnetic performance while still achieving cost benefits.
4Reliability
If sintering temperature is increased to improve density, then magnetic performance improves but production cost increases
Solution Approach 1:
The patent utilizes parameter changes during the preparation process, specifically controlling cooling rates and heat treatment conditions to achieve the desired dual-phase microstructure. By optimizing these parameters, the patent achieves high magnetic performance through proper phase formation and distribution without requiring excessively high sintering temperatures, thus resolving the contradiction between magnetic performance and production cost.
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 superior magnetic performances with a coercive force above 11 kOe and magnetic energy product over 30 MGOe, while reducing production costs and allowing for engineering-scale production with a lower Nd content and no heavy rare earth elements.
Implementation Method 1
aligned forming under a magnetic field
Implementation Method 2
followed by sintering and tempering
Data Source
AI summary
The invention discloses a low-cost double-main-phase Ce permanent magnet alloy and its preparation method, and belongs to technical field of rare earth permanent magnet material. The Ce permanent magnet alloy has a chemical formula of (Cex,Re1-x)aFe100-a-b-cBbTMc in mass percent, wherein 0.4≦x≦0.8, 29≦a≦33, 0.8≦b≦1.5, 0.5≦c≦2, Re is one or more selected from Nd, Pr, Dy, Tb and Ho elements, and TM is one or more selected from Ga, Co, Cu, Nb and Al elements; the Ce permanent magnet alloy has a double-main-phase structure with a low HA phase in (Ce,Re)—Fe—B and a high HA phase in Nd—Fe—B. The double-main-phase Ce permanent magnet alloy of the present invention prepared by using a double-main-phase alloy method greatly lowers the production cost of magnet while maintaining excellent magnetic performances.