High coercive force and high stability NdFeB magnet based on grain boundary reconstruction and its preparation method

Abstract

The invention discloses a high-coercivity and high-stability neodymium iron boron magnet and a preparation method based on crystal boundary reconstruction. The preparation method comprises the steps of separating design and preparation of main alloy and crystal boundary phase alloy powder, nano-modification of crystal boundary phase, powder mixing, magnetic field profiling, isostatic pressing, sintering and thermal treatment. According to the high-coercivity and high-stability neodymium iron boron magnet and the preparation method is based on crystal boundary reconstruction and combines with a rich heavy rear earth novel crystal boundary phase and nano-modification technology, namely the rich heavy rare earth novel crystal boundary phase is redesigned and synthesized, in the process of magnetic sintering and tempering, magnetic hardening is achieved through spread of the heavy rare earth element to the boundary layers of the principle phase crystal grain, and thus a high-coercivity magnetic is prepared under the condition that no or less heavy rear earth is added in the principle phase. Meanwhile the distribution of the crystal boundary and the form of the crystal grain boundary are optimized through a nano-modification method, a pinning domain wall restrains counter magnetic field nucleation and crystal grain growth, and thus high coercivity and high stability of the neodymium iron boron is achieved. The high-coercivity and high-stability neodymium iron boron magnet and preparation method based on crystal boundary reconstruction is simple in process, low in cost and suitable for large-scale volume production.

Description

technical field [0001] The invention relates to a NdFeB magnet with high coercive force and high stability based on grain boundary reconstruction and a preparation method. Background technique [0002] Nd-Fe-B has the incomparable advantages of other types of permanent magnet materials such as high magnetic energy product and high cost performance, and is currently the most widely used rare earth permanent magnet material. By 2015, the world demand for NdFeB products will be as high as 200,000 tons. It can be seen that NdFeB materials will still play an important role in the modern information technology industry for a long time in the future. [0003] The main technical indicators to measure the performance of NdFeB permanent magnets include remanence B r , the maximum energy product ( BH ) max ,Coercivity H c and Curie temperature T c . After years of hard work, based on relatively mature alloy composition design theory and preparation process optimization, B r ...

AI Technical Summary

Problems solved by technology

Under the traditional process, the Nd-rich grain boundary phase is naturally formed, and it is difficult to achieve effective regulation