Micro-structure-influence research on the double phase nano-composite permanent magnet
As new permanent magnets, double-phase nanocomposite permanent magnets have recently attracted considerable attention.
This type of alloys integrates advantages of hard magnetic phase’s high magnetocrystalline anisotropy and soft magnetic phase’s high saturation magnetization, and obtains the excellent magnetic properties through exchange-coupled interaction on a scale of the order nm. Theoretical estimation indicates that double-phase nanocomposite permanent magnet material’s energy product may reach as high as 800kJ/m3, higher than any kind of single-phase permanent-magnet material. This kind of material also has characteristics of low rare earth content and good
chemical stability, Therefore, it is of great practical value and to be the new generation of low price caking permanent-magnet material, it will have promising application prospect.
Firstly, this author studied the take-shape craft of double-phase nanocomposite permanent magnet material, including the performance by pressure and time’s maintenance to magnet’s density and the magnetism.
The result indicates that the magnet density increases along with the pressure and time. The magnet
density reaches the biggest one when pressure is 600MPa and time is 150s. When the pressure or the time is continually
increased, the magnet density will no longer increase, there is possibility to create break interior and reduce the production efficiency.
This suppressed craft was still used in following experiments.
Secondly, the author studied the agglutinate craft of double-phase nanocomposite permanent magnet material, which had two variables: high agglutinates- temperature and heat preservation time. Had determined the elevation of temperature mechanism according to the differential-thermal analysis curve, the elevation of temperature speed is 3~5℃. Three specimens were selected in experiment, their serial numbers were3#、4#、5#, separately used in different high agglutinates-temperature, and simultaneously different heat preservation time , the result is that the 4# is burn to be most compact, and
the compactness is the highest when the heat
preservation time is the 150min. According to the micro analysis, the Crystal grain of test specimen has ruled size, and the distribution is even,
and no crystalless phase exists.
Finally, the author studied the influence of adding element on the double-phase nanocomposite permanent magnet material, the author choose the representative replacement element Co and doping element Mo
in adding element, the recruitment control is below 1.0wt%, the experiment is divided into six groups, different group with different element
addition and different recruitment. Concluded by the micro analysis, among the six groups, the foemer of group adding with Mo element is better
than that adding with Co element. It has more tiny-even crystal grain, and among the group adding with Mo element, 0.5wt％Mo is the best one. The final result indicates that Co element actually has enhances the magnetism performance influence on craft
of NdFeB, and the Mo element mainly played the thin crystal grain role, the magnetism performance had the enhancement.
