Low-Neodymium Magnet Composition and Sintering
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Solution Overview
Problem
Current rare earth permanent magnet technologies face challenges in reducing production costs and maintaining high magnetic performance due to the high cost of neodymium (Nd) and the limitations of substituting Nd with cerium (Ce), which results in low magnetic torque and coercive force, and increased production costs.
Innovation Solution
A low-neodymium, high-performance magnet is developed by substituting 10% to 40% of Nd with La and Ce, and adding a small amount of TM elements like Ga, Co, Cu, or Al to improve coercive force, using a method involving rapid solidification, hydrogen crash, jet milling, aligned forming, and low-temperature sintering to achieve magnetic energy product (BH) of 40 MGOe or above and coercive force over 10 kOe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Nd is substituted by Ce to reduce cost, then production cost decreases, but magnetic torque and coercive force fall below requirements
Solution Approach 1:
The patent changes the substitution ratio parameter, limiting Ce substitution to 10-40% of total rare earth content rather than higher ratios used in prior art. This optimized parameter range maintains magnetic performance while achieving cost reduction. Additionally, the patent introduces TM element content as a new parameter (0.5-2%) to enhance coercive force and compensate for any performance loss from substitution.
Solution Approach 2:
The patent creates a composite rare earth system combining Nd, Pr, Ce, and La elements rather than using single-element substitution. This composite approach leverages the high magnetic performance of Nd/Pr while incorporating cost-effective Ce/La in controlled amounts. The multi-element composition allows synergistic effects that maintain overall magnetic properties despite partial substitution of expensive Nd.
2Adaptability or versatility
If multiple rare earth elements are smelted to create different magnet series, then component flexibility increases, but production cost increases greatly
Solution Approach 1:
The patent establishes a universal base composition formula [(Nd, Pr)100-x(Ce100-yLay)x]aFe100-a-b-cBbTMc that can produce multiple magnet grades through parameter adjustment rather than requiring separate smelting processes for each series. By universally applying this formula with varying x, y, a, b, and c values, manufacturers can achieve component flexibility while avoiding the cost penalties of multiple dedicated production lines.
Solution Approach 2:
The patent enables production of different magnet series and grades by changing compositional parameters (x, y, a, b, c) within the unified formula rather than through separate smelting processes. This parameter-based differentiation allows a single production system to generate multiple product variants, achieving versatility without the need for multiple specialized smelting facilities, thereby reducing overall production costs.
3Manufacturing precision
If sintering temperature is increased above 1060°C to improve densification, then grain size grows large, but magnetic performance worsens and production cost increases
Solution Approach 1:
The patent optimizes the sintering temperature parameter to a specific range (1000-1050°C) rather than using higher temperatures above 1060°C. This optimized temperature parameter achieves sufficient densification for high magnetic performance while preventing excessive grain growth that would deteriorate properties. The patent also optimizes holding time parameters at these moderate temperatures to ensure complete densification without the need for high-temperature 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
The solution significantly reduces production costs while maintaining high magnetic properties, allowing the magnets to meet market requirements with improved price/performance ratio and flexibility in component adjustment, suitable for large-scale engineering production.
Implementation Method 1
Nd—Fe—B features high residual magnetism Br, high coercive force Hcj and high magnetic energy product (BH)m
Implementation Method 2
the magnetic torque Js and anisotropic field HA of La2Fe14B/Ce2Fe14B falls far below that of Nd2Fe14B
Data Source
AI summary
The invention discloses a low-neodymium, non-heavy-rare-earth and high-performance magnet and its preparing method, and belongs to technical field of rare earth permanent magnetic material. The magnet has a chemical formula of [(Nd, Pr)100-x(Ce100-yLay)x]aFe100-a-b-cBbTMc, wherein x, y, a, b and c represent mass percents of corresponding elements respectively, 0≤x≤40%, 0≤y≤15%, 29≤a≤30%, 0.5≤b≤5%, 0.5≤c≤5%; and TM is one or more selected from Ga, Co, Cu, Nb and Al elements. A series of grades of magnets can be prepared with rapidly solidified strips of only three components. Component proportioning of magnet can also be directly performed by using mixed rare earth, so that the cost increased by further separation and purification of the rare earth is reduced. During the preparation of magnetic powder with a jet mill, an antioxidant lubricant which is composed of alcohol, gasoline and basic synthetic oil is added. A low-temperature sintering technology is adopted; and the sintering temperature is 1,010-1,050° C. and the annealing temperature is 450-550° C. The magnetic energy product (BH)m is more than 40 MGOe; and the coercive force Hcj is more than 10 kOe. The production time and the energy loss can be significantly reduced.