NdFeB Magnet Sintering Reducing Heavy Rare Earth

The patent applies local quality by concentrating heavy rare earth elements (Dy, Tb) specifically at the grain boundaries of the NdFeB magnet rather than uniformly distributing them throughout the material. This localized approach at the grain boundary phase achieves enhanced coercive force while minimizing overall rare earth consumption, directly resolving the technical contradiction between improving magnetic strength and reducing resource usage.

The patent employs parameter changes by precisely controlling the concentration and distribution of heavy rare earth elements in the grain boundary phase, optimizing their content to achieve maximum coercive force enhancement with minimum material usage. Additionally, the multi-stage sintering process parameters (temperature, time, atmosphere) are optimized to control grain growth and heavy rare earth distribution, further reducing rare earth consumption while maintaining high magnetic performance.

The patent applies segmentation by dividing the sintering process into multiple distinct stages: initial sintering stage (forming Nd2Fe14B phase and grain boundary phase), first aging stage (800-950°C for grain growth control), and second aging stage (different temperature for final optimization). Each stage serves a specific purpose in controlling microstructure evolution and heavy rare earth distribution, enabling optimized magnetic performance with controlled processing time.

The patent employs preliminary action by conducting the initial sintering stage to establish the basic microstructure and grain boundary phase formation before subsequent aging treatments. The first aging stage preliminarily controls grain growth and heavy rare earth distribution, preparing the microstructure for final optimization in the second aging stage. This sequential preliminary actions approach enables systematic microstructure control while managing overall processing time efficiently.