Preparation method for a neodymium-iron-boron magnet

A preparation method for NdFeB permanent magnet, the method including the steps of:

• a) Preparing main alloy flakes consisting of (Pr2Nd8)xFe100-x-y-zByMz, where M is at least one of Al, Co, Cu, Ga,Ti and Zr, and x, y and z is 28.5 wt. %≤x≤31.0 wt. %, 0.85 wt. %≤y≤0.98 wt. % and 0.5 wt. %≤z≤5.0 wt. %;
• b) Preparing auxiliary alloy flakes consisting of LuFe100-u-v-wBvMw, where L is one or more of the metals Pr and Nd, M is at least one of Al, Co, Cu, Ga, Ti and Zr, and u,v and w is 35.0 wt. %≤u≤45.0 wt. %, 0 wt. %≤v≤5.0 wt. % and 2.0 wt. %≤w≤10.0 wt. %;
• c) Mixing the main alloy flakes and the auxiliary alloy flakes in a predetermined rate, then performing a hydrogen decrepitation to produce alloy pieces,and then crushing the alloy pieces to an alloy powder by jet milling;
• d) Preparing a powder mixture including the alloy powder and an added heavy rare earth powder consisting of at least one of Dy and Tb;
• and
• e) Pressing the powder mixture to a green compact while applying a magnetic field, and thermal treatment of the green compact in a vacuum furnace to obtain the NdFeB permanent magnet.