Fabrication And Study Of Sintered NdFeB With Low Dy Content And High Thermal Stability

Sintered NdFeB rare earth permanent magnet, which has very excellent intrinsic magnetic properties, is the most popular permanent magnetic materials. With the rising of market demand and prices of raw materials, how to reduce the manufacture cost is very important. Meanwhile, the weak thermal stability of NdFeB limits its application at high temperatures. To solve these two problems, we systematically investigated the impacts of the optimization technology in the preparation process and various element additions on the magnet performance and thermal stability.Firstly, this thesis focused on the optimization of preparation technology and adjustment of the processing parameters of preparation. Through scanning electron microscope analysis and magnetic properties characterization, we finally decided to use the double alloy processing:NdFeB alloy thin belt are prepared by melt-Spinning at4m/s roller speed, the8hour insulation for hydrogen dehydrogenation at T=550℃,4200r/min for airflow grinding powder and adding1.5ml/kg antioxidants,2T magnetic field for oriented formation, addition of2ml/kg lubricant. And then cold isostatic pressing and the4hour insulation at T=1065℃, the2hour insulation at T=890℃and T=500℃for second annealing processing.The second part of the thesis is the optimization of composition design. The sintered NdFeB magnet was fabricated through adding proper Co, Al, Ga, Nb elements. After characterization of magnetic properties and analyzing of thermal stability, the main phase with (PrNd)29Co3Nb0.2Fe66.8B1and accessorial phase with (PrNd)10Dy20Cu2Al8Ga4Fe55were choosed for final fabrication. The mass ratio between main phase and accessorial phase was15:1.Compared with other products with same performance, the sintered NdFeB magnet synthesized by above preparation technology and composition design has lower Dy content (0.7%lower) and notable improvement of thermal stability.