Study On The Preparation And The Microstructure Of Melt-spun SmFe Alloys With TbCu₇-type Structure

Melt spun SmFeN bonded magnetic powder with TbCu7-type structure has high magnetic properties and corrosive-resistance and temperature and is a kind of promising new bonded permanent magnet material. Unlike Sm2Fe17Nx magnetic powder, SmFeN magnetic powder with TbCu7-type can be prepared into isotropic magnets, and this can reduce costs. At present, the preparation of industrialization has begun in Japan, but there is not much research on this subject at home.Preparation of single-phase melt spun SmFe Alloys with TbCu7-type is the key problem in the research. SmFe Alloys with TbCu7-type is a kind of metastable phase, and it can be obtained only when rapid cooling rate and Fe/Sm are controlled within a rational range. To obtain SmFe Alloys by high-speed water-cooling molybdenum roll and to obtain the best phase structure and microstructure by adjusting the Sm content and wheel speed and additive elements such as Zr, Co.Four kinds of Alloys with different component were designed, and the influence of Sm content, wheel speed and additive elements on phase structure and microstructure was discussed, as well as the variation of Sm volatilization. The main results were as follows:During Melting Process, Sm volatilization is about0.6wt%and has nothing to do with the compensation of Sm; during Melt-spun Process, Sm volatilization decreased gradually with increasing quenching rate. The decrease of Sm content as well as increased quenching rate is beneficial to obtain Sm-Fe alloys with TbCu7-type. With the decrease of Sm content, Sm-rich phase gradually disappeared and a-Fe dendrites gradually decreased. With the increase of quenching rate grain size decreases and composition becomes gradually uniform. The microstructure can be improved by change in Sm content and the addition of niobium of Zirconium, Cobalt, so as to improve magnetic properties.In addition, because of Non-wetting Phenomena between Alloy liquid and molybdenum roll, Spherical Alloy having a lot of a-Fe dendrites and fairly bad nitriding effect has appeared, and it is harmful to magnetic properties.