The magnetic properties and microstructure of Nd-Fe-B magnets prepared by spark plasma sintering with different die-upsetting processes were investigated. The results showed that the optimum magnetic properties of die...The magnetic properties and microstructure of Nd-Fe-B magnets prepared by spark plasma sintering with different die-upsetting processes were investigated. The results showed that the optimum magnetic properties of die-upset Nd-Fe-B magnets were obtained at 680 ℃ when the die-upset level was 60%, and the degree of magnetic alignment was 0.84. The microstructures showed that the coarse grains oc-curred predominantly within certain areas, and abnormal grain growth was not observed within the major areas of well-aligned grains. There existed many small spherical grains, which stacked together and were not aligned during die upsetting when the deformation temperature was 650 ℃. These small spherical grains grew up, and were aligned when the deformation temperature increased from 650 to 680 ℃, which could improve the crystallographic alignment of die-upset Nd-Fe-B magnets.展开更多
The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets ...The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets were obtained at the deformation temperature of 680 ℃. The anisotropy of Vickers hardness was more obvious at the die-upset level of 55%, and the Vickers hardness measured parallel to the c-axis was significantly lower than that perpendicular to the c-axis. The fracture toughness measured parallel to the c-axis first increased, and then decreased with increase in die-upset level. The maximum fracture toughness of Nd-Fe-B magnets was obtained at the die-upset level of 60%. The microstmcture showed that the width of defect layers and the average size of large grains increased, and the layered structure of die-upset Nd-Fe-B magnets was obviously different with increase in the die-upset level.展开更多
为提高传统纠检错(error detection and correction,EDAC)模块对星载SRAM中单粒子多位翻转(multiple bit upsets,MBU)的纠错率,提出一种能同时纠正多比特位翻转的技术,称为数据交错技术。参照版图交错法的原理,在FPGA的软件设计等级实...为提高传统纠检错(error detection and correction,EDAC)模块对星载SRAM中单粒子多位翻转(multiple bit upsets,MBU)的纠错率,提出一种能同时纠正多比特位翻转的技术,称为数据交错技术。参照版图交错法的原理,在FPGA的软件设计等级实现数据的交错存储,将单粒子的多位翻转分离后,分别通过EDAC模块纠正。仿真结果表明,该数据交错技术与(12,8)汉明码及(21,16)汉明码结合后,可将传统EDAC模块对单粒子引起的两位及三位翻转的纠错率从53.69%及28.91%提升至99.82%,以较低代价,实现了MBU大部分翻转形式的纠正。展开更多
基金supported by the National Natural Science Foundation of China (50801049)
文摘The magnetic properties and microstructure of Nd-Fe-B magnets prepared by spark plasma sintering with different die-upsetting processes were investigated. The results showed that the optimum magnetic properties of die-upset Nd-Fe-B magnets were obtained at 680 ℃ when the die-upset level was 60%, and the degree of magnetic alignment was 0.84. The microstructures showed that the coarse grains oc-curred predominantly within certain areas, and abnormal grain growth was not observed within the major areas of well-aligned grains. There existed many small spherical grains, which stacked together and were not aligned during die upsetting when the deformation temperature was 650 ℃. These small spherical grains grew up, and were aligned when the deformation temperature increased from 650 to 680 ℃, which could improve the crystallographic alignment of die-upset Nd-Fe-B magnets.
基金supported by National Natural Science Foundation of China (50801049)
文摘The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets were obtained at the deformation temperature of 680 ℃. The anisotropy of Vickers hardness was more obvious at the die-upset level of 55%, and the Vickers hardness measured parallel to the c-axis was significantly lower than that perpendicular to the c-axis. The fracture toughness measured parallel to the c-axis first increased, and then decreased with increase in die-upset level. The maximum fracture toughness of Nd-Fe-B magnets was obtained at the die-upset level of 60%. The microstmcture showed that the width of defect layers and the average size of large grains increased, and the layered structure of die-upset Nd-Fe-B magnets was obviously different with increase in the die-upset level.
文摘为提高传统纠检错(error detection and correction,EDAC)模块对星载SRAM中单粒子多位翻转(multiple bit upsets,MBU)的纠错率,提出一种能同时纠正多比特位翻转的技术,称为数据交错技术。参照版图交错法的原理,在FPGA的软件设计等级实现数据的交错存储,将单粒子的多位翻转分离后,分别通过EDAC模块纠正。仿真结果表明,该数据交错技术与(12,8)汉明码及(21,16)汉明码结合后,可将传统EDAC模块对单粒子引起的两位及三位翻转的纠错率从53.69%及28.91%提升至99.82%,以较低代价,实现了MBU大部分翻转形式的纠正。
