Pr_(83)Cu_(17)(wt%) grain boundary reconstruction was applied to prepare sintered NdFeB magnets. The effects of addition amount and annealing on the bending strength were investigated. The results show that Pr_(83)Cu_...Pr_(83)Cu_(17)(wt%) grain boundary reconstruction was applied to prepare sintered NdFeB magnets. The effects of addition amount and annealing on the bending strength were investigated. The results show that Pr_(83)Cu_(17) can not only effectively enhance the bending strength, but also change the mechanical anisotropy in two directions parallel and perpendicular to c-axis. The bending strength perpendicular to c-axis reaches 404 MPa in 10 wt% addition magnet, higher than 348 MPa along parallel direction. This change is attributed to the preferred distribution of boundary phases, i.e., ductile(Nd,Pr)-Fe-Cu phase along perpendicular direction to c-axis and(Nd,Pr)-Fe phase along parallel direction. Moreover, the Cu migration during 480 ℃ annealing is found to be related to this boundary phase distribution.展开更多
Nd-Fe-B permanent magnets doped with CuZn5 powders were prepared via conventional sintered method. The effects of CuZn5 contents on magnetic properties and corrosion resistance of the magnets were sys- tematically stu...Nd-Fe-B permanent magnets doped with CuZn5 powders were prepared via conventional sintered method. The effects of CuZn5 contents on magnetic properties and corrosion resistance of the magnets were sys- tematically studied. It shows that the remanence, coercivity, and maximum energy product decrease gradually with the increase in CuZn5 doping content. The magnet＇s corrosion kinetics in autoclaves environment and its electrochemical properties in electrolytes were also examined. It is interesting to see that the weight loss of 3.5 wt% and 4.5 wt% CuZn5 powders doping magnets is only 1 and 0 mg.cm^-2 after autoclaves test at 121 ℃, 2 × 10^5 Pa for 500 h, respectively, which is much lower than that of the magnets without CuZn5 doping. Electrochemical results show that the CuZn5 powders doping magnets display more positive corrosion potential （Eoorr） and lower corrosion current density （Icorr） than those of the original magnets without CuZn5 doping in sulphuric acid electrolyte and distilled water. It is, therefore, concluded that doping CuZn5 powders is a promising way to enhance the corrosion resistance of sintered Nd-Fe-B magnets.展开更多
基金supported by National Natural Science Foundation of China(51401021)the State Key Laboratory Advanced Metals and Materials(20162-14)
文摘Pr_(83)Cu_(17)(wt%) grain boundary reconstruction was applied to prepare sintered NdFeB magnets. The effects of addition amount and annealing on the bending strength were investigated. The results show that Pr_(83)Cu_(17) can not only effectively enhance the bending strength, but also change the mechanical anisotropy in two directions parallel and perpendicular to c-axis. The bending strength perpendicular to c-axis reaches 404 MPa in 10 wt% addition magnet, higher than 348 MPa along parallel direction. This change is attributed to the preferred distribution of boundary phases, i.e., ductile(Nd,Pr)-Fe-Cu phase along perpendicular direction to c-axis and(Nd,Pr)-Fe phase along parallel direction. Moreover, the Cu migration during 480 ℃ annealing is found to be related to this boundary phase distribution.
基金financially supported by the National High Technology Research and Development Program of China (No. 2012AA063201)the National Natural Science Foundation of China (Nos. 51001002 and 51371002)+2 种基金the International S&T Cooperation Program of China (No.2015DFG52020)the Natural Science Foundation of Anhui Province (No.1408085MKL72)the 2011 Cooperative Innovation Center of Beijing University of Technology
文摘Nd-Fe-B permanent magnets doped with CuZn5 powders were prepared via conventional sintered method. The effects of CuZn5 contents on magnetic properties and corrosion resistance of the magnets were sys- tematically studied. It shows that the remanence, coercivity, and maximum energy product decrease gradually with the increase in CuZn5 doping content. The magnet＇s corrosion kinetics in autoclaves environment and its electrochemical properties in electrolytes were also examined. It is interesting to see that the weight loss of 3.5 wt% and 4.5 wt% CuZn5 powders doping magnets is only 1 and 0 mg.cm^-2 after autoclaves test at 121 ℃, 2 × 10^5 Pa for 500 h, respectively, which is much lower than that of the magnets without CuZn5 doping. Electrochemical results show that the CuZn5 powders doping magnets display more positive corrosion potential （Eoorr） and lower corrosion current density （Icorr） than those of the original magnets without CuZn5 doping in sulphuric acid electrolyte and distilled water. It is, therefore, concluded that doping CuZn5 powders is a promising way to enhance the corrosion resistance of sintered Nd-Fe-B magnets.
