Nd5Fe17 Rare Earth Magnet Phase Balance
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Solution Overview
Problem
Rare earth permanent magnets with an intermetallic compound of Sm5Fe17 as the main phase have lower residual magnetization and coercivity compared to those with Nd2Fe14B, and substituting Sm with Pr or Nd to improve magnetic properties results in reduced coercivity due to increased content ratios of other phases.
Innovation Solution
A rare earth permanent magnet with a compound of Nd5Fe17 type crystal structure as the main phase, comprising two or more rare earth elements including Sm and one of Pr or Nd, with controlled content ratios and X-ray diffraction characteristics to enhance residual magnetization and coercivity, incorporating a sub phase with specific intensity ratios to optimize magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Sm is substituted by Pr or Nd to improve residual magnetization, then residual magnetization is improved, but coercivity is reduced greatly due to increased content ratio of phases other than main phase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of rare earth elements (R) and transition metals (T), specifically setting R content at 20.0-37.1 at% and T content at 47.9-80.0 at%, with Sm comprising 50.0-99.0 at% of the rare earth elements. This quantitative parameter optimization resolves the contradiction by finding the optimal balance point where both residual magnetization and coercivity are maximized simultaneously.
Solution Approach 2:
The patent employs composite materials by creating a multi-phase structure consisting of a main phase with Nd5Fe17 type crystal structure and controlled sub-phases. The composite nature allows different phases to contribute different properties: the main phase provides high coercivity while the sub-phases contribute to residual magnetization, thus resolving the contradiction between these two magnetic properties.
2Measurement precision
If content ratio of R is increased to improve magnetic properties, then residual magnetization improves, but coercivity is reduced due to phase composition changes
Solution Approach 1:
The patent resolves this contradiction through precise parameter control of the R content ratio, establishing it within the specific range of 20.0-37.1 at%. This quantitative optimization ensures that the main phase Nd5Fe17 type crystal structure remains dominant while allowing sufficient rare earth content to maintain high residual magnetization, thereby preventing coercivity reduction.
Solution Approach 2:
The patent applies local quality by creating a non-uniform phase distribution where the main phase with Nd5Fe17 type crystal structure is predominant, and sub-phases are present in controlled amounts. This local phase differentiation allows different regions to contribute differently: the main phase ensures high coercivity while sub-phases enhance residual magnetization, resolving the contradiction.
3Reliability
If content ratio of T is increased to improve coercivity, then coercivity improves, but residual magnetization is reduced
Solution Approach 1:
The patent resolves this contradiction by optimizing the T content ratio within the range of 47.9-80.0 at%, with specific embodiments using 63.0-79.7 at%. This parameter optimization ensures sufficient transition metal content to maintain high coercivity through the Nd5Fe17 type crystal structure while preventing excessive T content that would reduce residual magnetization.
Solution Approach 2:
The patent employs composite materials by creating a balanced multi-phase structure where the main phase (Nd5Fe17 type) and sub-phases work synergistically. The main phase provides high coercivity through its crystal structure, while the controlled sub-phases contribute to residual magnetization, thus resolving the contradiction between coercivity and residual magnetization.
Data Source
AI summary
A rare earth permanent magnet that is high in residual magnetization and coercivity is obtained and includes R and T. A main phase of crystal grains having an Nd5Fe17 type crystal structure is included. In an X-ray diffraction profile drawn by performing an XRD measurement for a rare earth permanent magnet, peaks of detected intensity are present in specific ranges. In which the detected intensity of the peak with the highest detected intensity in the range of 41.60°<2θ(°)<42.80° is set as α, the detected intensity of the peak with the highest detected intensity in the range of 34.38°<2θ(°)<34.64° is set as β, and the detected intensity of the peak with the highest detected intensity in the range of 38.70°<2θ(°)<41.20° is set as γ, 0.38<α/β<0.70 and 0.45<γ/β<0.70 are established. The peak with the highest detected intensity in the range of 34.38°<2θ(°)<34.64° is a peak derived from the Nd5Fe17 type crystal structure.