ThMn12 Magnetic Compound Composition and Cooling Control
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Solution Overview
Problem
Current high-performance permanent magnets, such as Nd-Fe-B, face challenges in achieving both high anisotropy field and saturation magnetization, with rare earth element-iron magnetic compounds having a ThMn12 type crystal structure falling short in saturation magnetization compared to Nd-Fe-B magnets.
Innovation Solution
A magnetic compound with the formula (R(1-x)Zr_x)M(Fe(1-y)Co_y)T_cM_dA_e, where R represents rare earth elements, Zr, Ti, V, Mo, or W, M includes unavoidable impurities, and A is N, C, or P, is developed, with specific composition and production methods to enhance anisotropy field and saturation magnetization by controlling the volume percentage of the α-(Fe,Co) phase and cooling rate during production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If T content is reduced to increase magnetic element percentages, then saturation magnetization improves, but crystal structure stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the T content within 0.5-5.0 at% and Zr content within 0.1-5.0 at% ranges. This optimization balances the competing requirements: enough T to stabilize the ThMn12 crystal structure, but limited T to maintain high saturation magnetization. The specific compositional parameters achieve both structure stability and magnetic performance simultaneously.
Solution Approach 2:
The patent creates a composite material system by combining rare earth elements (R), transition metals (Fe, Co, T), and Zr in specific proportions. This composite approach allows the material to exhibit both the crystal structure stability provided by T and the high magnetization from Fe-Co magnetic elements, while Zr enhances coercivity. The composite formulation resolves the contradiction by distributing functions across multiple elements.
2Quantity of substance
If cooling rate is increased to reduce α-(Fe,Co) phase deposition, then saturation magnetization improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the cooling rate within 1×10²-1×10⁴ K/s range. This controlled parameter adjustment suppresses excessive α-(Fe,Co) phase formation during solidification, thereby improving saturation magnetization. The specific cooling rate parameter achieves the desired microstructure without requiring overly complex manufacturing equipment.
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 magnetic compound achieves improved anisotropy field and saturation magnetization by reducing the T content and α-(Fe,Co) phase volume, resulting in a material with characteristics exceeding those of existing ThMn12 type compounds, particularly in motor applications.
Implementation Method 1
a magnetic compound having a ThMn12 type crystal structure with high anisotropy field and high saturation magnetization
Implementation Method 2
adjusting the cooling rate of molten alloy during the production process
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
Provided is a magnetic compound represented by the formula (R(1-x)Zrx)a(Fe(1-y)Coy)bTcMdAe (wherein R represents one or more rare earth elements, T represents one or more elements selected from the group consisting of Ti, V, Mo, and W, M represents one or more elements selected from the group consisting of unavoidable impurity elements, Al, Cr, Cu, Ga, Ag, and Au, A represents one or more elements selected from the group consisting of N, C, H, and P, 0≤x≤0.5, 0≤y≤0.6, 4≤a≤20, b=100-a-c-d, 0<c<7, 0≤d≤1, and 1≤e≤18), in which a main phase of the magnetic compound includes a ThMn12 type crystal structure, and a volume percentage of an α-(Fe,Co) phase is 20% or lower.