The high-temperature magnetic perfo rmance and micro structure of Sm_(1-x)Gd_(x)(Co_(bal)Fe_(0.09)Cu_(0.09)Zr_(0.025))_(7.2)(x=0.3,0.5) magnets were investigated.With the isothermal aging time decreasing from 11 to 3 ...The high-temperature magnetic perfo rmance and micro structure of Sm_(1-x)Gd_(x)(Co_(bal)Fe_(0.09)Cu_(0.09)Zr_(0.025))_(7.2)(x=0.3,0.5) magnets were investigated.With the isothermal aging time decreasing from 11 to 3 h,the temperature coefficient of intrinsic coercivity in the temperature range of 25-500℃,β_(25-500℃),was optimized from -0,167%/℃ to-0.112%/℃ for x=0.3 magnets.The noticeable enhancement(~33%) of temperature stability is correlated with the increased content of 1:5H cell boundary phase and its relatively high Curie temperature as well.However,for the x=0.5 magnet,it is found that the presence of Sm_(5)Co_(19) phases and wider nanotwin variants hinder the formation of 1:5H cell boundary phase.The insufficient 1:5H is not beneficial to the proper redistribution of Cu in cell boundary,making the x=0.5 magnet difficult to achieve higher temperature stability.Consequently,the approach of adjusting the isothermal aging process can offer guidance for attaining superior magnetic performance in the temperature range from 25 to 500℃ for Gd-substituted Sm_(2)Co_(17)-type magnets.展开更多
Sm-Co permanent magnets are widely used in aerospace equipments,tubes,sensors and hybrid electric vehicles due to their excellent magnetic properties at both room and high temperatures.Compared to that of Nd-Fe-B magn...Sm-Co permanent magnets are widely used in aerospace equipments,tubes,sensors and hybrid electric vehicles due to their excellent magnetic properties at both room and high temperatures.Compared to that of Nd-Fe-B magnets,the capability of reliably operating at temperatures up to 500℃ is the biggest preponderance of Sm-Co permanent magnets.However,the reliable high-temperature magnetic properties are susceptible to composition and technique processes.So,appropriate composition and matched technique processes are prerequisites for good high-temperature magnetic properties.This review mainly emphasizes the influences of Sm,Fe,Cu and Zr contents and technique processes on development of high-temperature performance and discusses the controversial hightemperature coercivity mechanism of 2:17-type high-temperature Sm-Co magnets.展开更多
Anisotropic MnBi/NdFeB （MnBi contents of 0 wt%, 20 wt%, 40 wt%, 60 wt%, 80 wt%, and 100 wt%） hybrid bonded magnets were prepared by molding compression using MnBi powders and commercial hydro-genation disproportiona...Anisotropic MnBi/NdFeB （MnBi contents of 0 wt%, 20 wt%, 40 wt%, 60 wt%, 80 wt%, and 100 wt%） hybrid bonded magnets were prepared by molding compression using MnBi powders and commercial hydro-genation disproportionation desorption and recombination （HDDR） NdFeB powders. Magnetic measurements at room temperature show that with MnBi content increasing, the magnetic properties of the MnBi/NdFeB hybrid bonded magnets all decrease gradually, while the density of the hybrid magnets improves almost linearly. In a temperature range of 293-398 K, the coercivity temperature coefficient of the hybrid magnets improves gradually from -0.59 %.K^-1 for the pure NdFeB bonded magnet to -0.32 %.K^-1 for the hybrid bonded magnet with 80 wt% MnBi, and the pure MnBi bonded magnet exhibits a positive coercivity temperature coefficient of 0.61%-K^-1.展开更多
基金Project supported by the National Key Research and Development Program of China (2021YFB3503100,2022YFB3505303,2021YFB3501500)the Key Technology Research and Development Program of Shandong Province (2019JZZY020210)。
文摘The high-temperature magnetic perfo rmance and micro structure of Sm_(1-x)Gd_(x)(Co_(bal)Fe_(0.09)Cu_(0.09)Zr_(0.025))_(7.2)(x=0.3,0.5) magnets were investigated.With the isothermal aging time decreasing from 11 to 3 h,the temperature coefficient of intrinsic coercivity in the temperature range of 25-500℃,β_(25-500℃),was optimized from -0,167%/℃ to-0.112%/℃ for x=0.3 magnets.The noticeable enhancement(~33%) of temperature stability is correlated with the increased content of 1:5H cell boundary phase and its relatively high Curie temperature as well.However,for the x=0.5 magnet,it is found that the presence of Sm_(5)Co_(19) phases and wider nanotwin variants hinder the formation of 1:5H cell boundary phase.The insufficient 1:5H is not beneficial to the proper redistribution of Cu in cell boundary,making the x=0.5 magnet difficult to achieve higher temperature stability.Consequently,the approach of adjusting the isothermal aging process can offer guidance for attaining superior magnetic performance in the temperature range from 25 to 500℃ for Gd-substituted Sm_(2)Co_(17)-type magnets.
基金financially supported by the National Natural Science Foundation of China(Nos.51871063,51571064 and 51590882)。
文摘Sm-Co permanent magnets are widely used in aerospace equipments,tubes,sensors and hybrid electric vehicles due to their excellent magnetic properties at both room and high temperatures.Compared to that of Nd-Fe-B magnets,the capability of reliably operating at temperatures up to 500℃ is the biggest preponderance of Sm-Co permanent magnets.However,the reliable high-temperature magnetic properties are susceptible to composition and technique processes.So,appropriate composition and matched technique processes are prerequisites for good high-temperature magnetic properties.This review mainly emphasizes the influences of Sm,Fe,Cu and Zr contents and technique processes on development of high-temperature performance and discusses the controversial hightemperature coercivity mechanism of 2:17-type high-temperature Sm-Co magnets.
基金financially supported by the National Natural Science Foundation of China(No.51271005)the Beijing Municipal Natural Science Foundation(No.2122006)+2 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(No.32009001201301)the Project from Samsung Advanced Institute of Technology(No.46009001201402)the Fundamental Research Foundation of Beijing University of Technology(No.009000514313002)
文摘Anisotropic MnBi/NdFeB （MnBi contents of 0 wt%, 20 wt%, 40 wt%, 60 wt%, 80 wt%, and 100 wt%） hybrid bonded magnets were prepared by molding compression using MnBi powders and commercial hydro-genation disproportionation desorption and recombination （HDDR） NdFeB powders. Magnetic measurements at room temperature show that with MnBi content increasing, the magnetic properties of the MnBi/NdFeB hybrid bonded magnets all decrease gradually, while the density of the hybrid magnets improves almost linearly. In a temperature range of 293-398 K, the coercivity temperature coefficient of the hybrid magnets improves gradually from -0.59 %.K^-1 for the pure NdFeB bonded magnet to -0.32 %.K^-1 for the hybrid bonded magnet with 80 wt% MnBi, and the pure MnBi bonded magnet exhibits a positive coercivity temperature coefficient of 0.61%-K^-1.
