Microstructure and magnetic properties were studied for the commercial Sm(Co FeCuZr)_(z) magnets before and after post annealing treatment.The results show that the phases composition and orientation of the magnet do ...Microstructure and magnetic properties were studied for the commercial Sm(Co FeCuZr)_(z) magnets before and after post annealing treatment.The results show that the phases composition and orientation of the magnet do not change after post annealing treatment,but the substantial redistribution of Cu element within multiscale(the microscale crystal grain and the nanoscale cellular structure) is observed simultaneously.In detail,along with the Cu redistribution,the thickness of the Cu-rich Sm(Co,Cu)_(5) cell boundary becomes thinner,and the Cu concentration in the boundary increases sharply.The pinning field of domain walls and corresponding coercivity increase remarkably with slight remanence and maximum energy product loss,and the overall magnetic performance of(BH)_(max)(MGOe)+H_(Cj)(kOe)increases by 54.3% as a result.Moreover,the thermal stability of the magnet improves as well.On the other hand,Cu-lean phenomenon was observed along the grain boundary region,triggering to magnetic domain reversal process and slightly undermining the squareness of the demagnetization curve of the magnet.展开更多
The evolution of the microstructure,microchemistry and magnetic properties of the Sm(CobalFe_(0.28)-CuyZrx)_(7.6)magnets with different Zr and Cu contents was investigated.It is found that the coercivity of the Sm(Co,...The evolution of the microstructure,microchemistry and magnetic properties of the Sm(CobalFe_(0.28)-CuyZrx)_(7.6)magnets with different Zr and Cu contents was investigated.It is found that the coercivity of the Sm(Co,Fe,Cu,Zr)_(z)magnets is sensitive to Zr content.The deficiency of Zr content causes heterogeneity of Cu and Fe distributions,while an excessive Zr content leads to the formation of a SmCoZr impurity phase.The cellular structure and distribution of Cu concentration.gradient between the cell boundary phase and cell pha se are destroyed by inappropriate Zr content,which results in a reduction of coercivity.The Cu concentration difference between the cell boundary phase and cell phase increases with increasing Cu content.The coercivity of the Sm(CobalFe_(0.28)CuyZ_(r0.02))_(7.6)magnets increases from 10.4 to 25.4 kOe for y=0.05 and y=0.07.However,the excess of Cu element destroys the cell boundary phase and enlarges the cell size,resulting in a significant decrease of squareness and energy density.The optimum performance(remanence of 11.4 kG,coercivity of 25.4 kOe,maximum magnetic ene rgy product of 30.4 MGOe)was obtained for the Sm(Co_(0.63)Fe_(0.28)Cu_(0.07)Zr_(0.02))_(7.6)magnet.展开更多
Sm(CoFeCuZr)zsintered permanent magnet has been attracting a great deal of attention by virtue of its high-temperature magnetic properties,low temperature coefficient and good corrosion and oxidation resistance.The mi...Sm(CoFeCuZr)zsintered permanent magnet has been attracting a great deal of attention by virtue of its high-temperature magnetic properties,low temperature coefficient and good corrosion and oxidation resistance.The microstructures and magnetic properties of Sm(Co_(ba1)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet prepared by a traditional powder metallurgy method were investigated.Tunable magnetic properties,especially the maximum magnetic energy product,(BH)max,were obtained through adjusting solution-treated temperatures.With solution-treated temperature increasing from 1155 to 1195℃,remanence(Br)almost keeps constant and knee point coercivity(Hk),magnetic induction coercivity(H_(cb))and(B_(H))maxfirst increase and then decrease.The intrinsic coercivity(H_(cj))of magnet solution-treated at 1195℃is 738 kA·m^(-1),which is less than 2/5 that of magnet solution-treated at 1183℃(>1927 kA·m^(-1)).The reason that magnet solution-treated at 1195℃shows lower Hcjthan magnet solution-treated at 1183℃is considered to be mainly related to the fact that there are a lot of cells with abnormally small size.In addition,the lattice constant of Sm(Co_(bal)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet solution-treated at 1195℃,given by indexing highresolution transition electron microscope(HRTEM)results,is considered to be related to the formation of cells with abnormally small size which decreases H_(cj).展开更多
基金Project supported by the National Natural Science Foundation of China(51871005,51931007)the Key Program of Science and Technology Development Project of Beijing Municipal Education Commission of China(KZ202010005009)。
文摘Microstructure and magnetic properties were studied for the commercial Sm(Co FeCuZr)_(z) magnets before and after post annealing treatment.The results show that the phases composition and orientation of the magnet do not change after post annealing treatment,but the substantial redistribution of Cu element within multiscale(the microscale crystal grain and the nanoscale cellular structure) is observed simultaneously.In detail,along with the Cu redistribution,the thickness of the Cu-rich Sm(Co,Cu)_(5) cell boundary becomes thinner,and the Cu concentration in the boundary increases sharply.The pinning field of domain walls and corresponding coercivity increase remarkably with slight remanence and maximum energy product loss,and the overall magnetic performance of(BH)_(max)(MGOe)+H_(Cj)(kOe)increases by 54.3% as a result.Moreover,the thermal stability of the magnet improves as well.On the other hand,Cu-lean phenomenon was observed along the grain boundary region,triggering to magnetic domain reversal process and slightly undermining the squareness of the demagnetization curve of the magnet.
基金the National Natural Science Foundation of China(51871005,51931007)the International S&T Cooperation Program of China(2015DFG52020)。
文摘The evolution of the microstructure,microchemistry and magnetic properties of the Sm(CobalFe_(0.28)-CuyZrx)_(7.6)magnets with different Zr and Cu contents was investigated.It is found that the coercivity of the Sm(Co,Fe,Cu,Zr)_(z)magnets is sensitive to Zr content.The deficiency of Zr content causes heterogeneity of Cu and Fe distributions,while an excessive Zr content leads to the formation of a SmCoZr impurity phase.The cellular structure and distribution of Cu concentration.gradient between the cell boundary phase and cell pha se are destroyed by inappropriate Zr content,which results in a reduction of coercivity.The Cu concentration difference between the cell boundary phase and cell phase increases with increasing Cu content.The coercivity of the Sm(CobalFe_(0.28)CuyZ_(r0.02))_(7.6)magnets increases from 10.4 to 25.4 kOe for y=0.05 and y=0.07.However,the excess of Cu element destroys the cell boundary phase and enlarges the cell size,resulting in a significant decrease of squareness and energy density.The optimum performance(remanence of 11.4 kG,coercivity of 25.4 kOe,maximum magnetic ene rgy product of 30.4 MGOe)was obtained for the Sm(Co_(0.63)Fe_(0.28)Cu_(0.07)Zr_(0.02))_(7.6)magnet.
基金financially supported by the National Basic Research Program of China(No.2014CB643701)the National Natural Science Foundation(No.51171048)
文摘Sm(CoFeCuZr)zsintered permanent magnet has been attracting a great deal of attention by virtue of its high-temperature magnetic properties,low temperature coefficient and good corrosion and oxidation resistance.The microstructures and magnetic properties of Sm(Co_(ba1)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet prepared by a traditional powder metallurgy method were investigated.Tunable magnetic properties,especially the maximum magnetic energy product,(BH)max,were obtained through adjusting solution-treated temperatures.With solution-treated temperature increasing from 1155 to 1195℃,remanence(Br)almost keeps constant and knee point coercivity(Hk),magnetic induction coercivity(H_(cb))and(B_(H))maxfirst increase and then decrease.The intrinsic coercivity(H_(cj))of magnet solution-treated at 1195℃is 738 kA·m^(-1),which is less than 2/5 that of magnet solution-treated at 1183℃(>1927 kA·m^(-1)).The reason that magnet solution-treated at 1195℃shows lower Hcjthan magnet solution-treated at 1183℃is considered to be mainly related to the fact that there are a lot of cells with abnormally small size.In addition,the lattice constant of Sm(Co_(bal)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet solution-treated at 1195℃,given by indexing highresolution transition electron microscope(HRTEM)results,is considered to be related to the formation of cells with abnormally small size which decreases H_(cj).
