R-T-B Magnet Alloy Composition for Coercivity and Crystal Homogeneity

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Solution Overview

Problem

Existing R-T-B based permanent magnets face challenges in achieving improved magnetic properties due to the presence of fine R-rich phases and columnar crystal structures that affect their coercivity and homogeneity.

Innovation Solution

The alloy for R-T-B based permanent magnets is formulated with a specific area ratio of non-columnar crystal structures between 1.0% and 30.0% in its cross section, along with controlled compositions of R, T, and B, and a manufacturing process that includes pulverization, pressing, sintering, and heat treatment to enhance magnetic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the alloy contains fine R-rich phases and columnar crystal structures, then the manufacturing process is simpler, but the coercivity and magnetic homogeneity deteriorate

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcoercivity and magnetic homogeneity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the crystal structure parameter by controlling the area ratio of non-columnar crystal structure to be 1.0% or more and 30.0% or less. This parameter control transforms the harmful fine R-rich phases and columnar crystal structures into a controlled non-columnar crystal structure, improving coercivity and magnetic homogeneity while maintaining manufacturing simplicity through conventional casting processes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the area ratio of non-columnar crystal structure is increased, then coercivity and magnetic anisotropy improve, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvecoercivity and magnetic anisotropyVSAvoidarea ratio control precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention establishes a specific parameter range (1.0% or more and 30.0% or less for non-columnar crystal structure area ratio) that balances performance improvement with manufacturing feasibility. This parameter specification enables conventional manufacturing processes to achieve the desired crystal structure without requiring extreme precision control.

Inventive Principle:

Principle #35Parameter changes

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 resulting R-T-B based permanent magnets exhibit enhanced high-temperature coercivity (HcJ) and room-temperature magnetic anisotropy (Hk/HcJ) by optimizing the non-columnar crystal structure ratio, leading to improved magnetic performance.

Implementation Method 1

an area ratio of a non-columnar crystal structure in a cross section of the alloy is 1.0% or more and 30.0% or less

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 2

a method for manufacturing an R-T-B based permanent magnet according to the present disclosure includes a step of pulverizing the alloy for an R-T-B based permanent magnet

Methodology Applied

Scientific EffectMechanical fracture: Fracture Mechanics

Data Source

PatentUS12597541B2Alloy for R-T-B based permanent magnet and method for manufacturing R-T-B based permanent magnet

Publication Date: 2026.04.07 TDK CORP

AI summary

To provide an alloy for an R-T-B based permanent magnet from which an R-T-B based permanent magnet having improved magnetic properties can be manufactured. The alloy for an R-T-B based permanent magnet contains R, T, and B, in which R is a rare earth element, T is a transition metal element, and B is boron. An area ratio of a non-columnar crystal structure in a cross section is 1.0% or more and 30.0% or less.