Study On The Key Preparation Technology Of Sm₂Co₁₇ Permanent Magnets For High Magnetic Properties

With the development of aerospace technology and the expanding of precision instrument applications,researchers propose high requirements for the permanent magnets.2:17-type permanent magnets are attracted widely attention due to high magnetic properties and well temperature stability.In this paper,the effect of milling process,heat treatment process for particle size distribution,magnetic properties and microstructure of 2:17-type permanent magnets have been studied systemtically.The main study of this research includes:1.The effect of milling process on particle size distribution has been studued.?1?The XRD results show that the main phase of the original alloy are 1:5 phase and 2:17 phase,where the 2:17 phase content take up more than 80.?2?Using the milling process,when the milling time extended from 6h to 8h hours,the magnetic particles reduced from 8.9 ?m to 5.7 ?m,the half width decreases from 13.0?m to 5.4?m,uniformity exaltation.Continue to extend the milling time to 11 h,the powder particle change is not obvious.With the milling time increases,the remanence from 10.21 kG increase to 10.95 kG,.Milling using a jet mill,when the jet mill speed increased from 2600 r/min to 4400 r/min,the magnetic particles reduced from 7.9 ?m to 4.9 ?m,Half width is reduced from 9.3 ?m to 5.2 ?m,uniformity exaltation.Continue to improve the speed to 4800 r / min,the powder particle change is not obvious.2.The microstructure,magnetic domain structure and magnetic properties variation of the sintering-solid solution stage have been studied.?1?The XRD results show that the main phase of the magnetic particle are 1:5 phase and 2:17 phase,which the 1:5 phase have lost.In the sintering-solid solution process,the 1:5 phase reduce and the 2:17 phase increase.When the solid solution temperature is 1180? and the holding time is 60 min,the 2:17H phase transform to 2:17H phase totally.?2?When the sintering condition is 1210? *80 min and the solid solution condition is 1180? *60 min,the magnet have the best magnetic properties,which is B_r=11.16 kG,H_cj>21.35 kOe,?BH?_max= 28.3 MGOe?3.The microstructure,magnetic domain structure and magnetic properties variation of the aging stage have been studied.?1?The XRD results show that the main phase of the magnetic is 2:17 phase,and a small amount of 1:5 phase and 2:7 phase.With the aging performed,the 2:7 phase peak decreases,indicating that the phase gradual break down.?2?The TEM results show that magnet begins to form cellular structure and cellular organization grew older and the cell wall phase becomes complete and continuous with the ageing going.The EDS results show that there are a great amount of Fe and Cu elements spreading from the cellular structure to the cell wall phase in the cooling process.?3?At the one aging process,when the holding time is 5h and the cooling time is 10 h,the magnet have the best magnetic properties,which is B_r=10.85 kG,H_cj>21.35 kOe,?BH?_max=28.02 MGOe.At the multistage aging,when holding 5h at each of 7 00?,600? ? 500?,the magnet have the best magnetic properties,which is B_r=10.75 kG,H_cj=22.00 kOe,?BH?_max=27.4 MGOe?...