Studies On Hydrogen Decrepitation And Electric Field Sintering Of NdFeB Alloys

Hydrogen decrepitation and sintering are the key working procedures in the preparation of NdFeB sintered magnets. However, hydrogen decrepitation has been mainly used as a means of crashing NdFeB alloys for recent 20 years, more researches on its techniques and theories are rather short. Meanwhile, comparing with the existing sintering ways of NdFeB alloys, there is no doubt that it has very important significance if we can find a new faster way in magnet preparation, and it will be more efficient and have lower energy consumption. Therefore, working on study and exploration on hydrogen decrepitation and electric field fast sintering of NdFeB alloys will not only have innovations, but also have important scientific and engineering values.The results of study on hydrogen decrepitation process of NdFeB alloys show that there obviously exists an incubation period before NdFeB alloys begin to absorb hydrogen, and that the higher the hydrogen pressure and temperature are, the smaller the alloy granularity is, and the less the oxidation is, the shorter the incubation periods are. The incubation phenomenon and the effects of temperature and hydrogen pressure on incubation can be explained with the theory of adsorption. After NdFeB alloys begin to absorb hydrogen, there will be three stages: stage of slow absorption by Nd-rich phases, stage of rapid absorption mainly by Nd2Fe14B phases, and stage of extremely slow absorption by the Nd-rich phases and main phases in the core of alloys. With increase of hydrogen pressure and temperature, the rates of hydrogen...