Sm2Co17永磁体的显微组织及其对矫顽力的影响

探讨了Sm(CobalFe0.197Cu0.049Zr0.026)7.5,Sm(CobalFe0.197Cu0.062Zr0.034)7.5永磁体的显微组织及其对矫顽力的影响.Sm2Co17永磁体由2:17相和1:5相两相所形成的胞状组织构成,并影响材料矫顽力的大小.在高矫顽力磁体的单晶表面有大量取向一致的沟痕,而不同晶粒内部的沟痕取向不同;沟痕较多时,磁体内所形成的1:5相增多,对畴壁的钉扎能力增强,有利于内禀矫顽力的提高.磁体表面的白色物质含Sm较多时可降低矫顽力.     

新型高温永磁体的研制

通过分析影响磁体高温性能的因素,设计了新磁体的成分为:Cu含量高,Fe含量低,Zr适量,Sm含量高;采用粉末冶金工艺制备了高温Sm_2(CoFeCuZr)_(17)永磁体。制得的磁体室温磁性能为:B_r1.075 T,H_(ei)2 098.2 kA/m,H_(eb) 776.1 kA/m,H_k843.8 kA/m,(BH)_(max)210.0 kj/m~3;在200℃时的磁性能为:B_r0.991 T,H_(ci)1 175.7 kA/m,H_(cb)531.7 kA/m,H_k577.9 kA/m,(BH)_(max)172.5 kJ/m~3;矫顽力温度系数β(20～200℃)为-0.24％/℃。经理论分析和实验验证,磁体的使用温度均超过400℃,为高温环境(高于400℃)提供了一种实用性永磁材料。     

合金成分对高温Sm(Co,Fe,Cu,Zr)z磁性能与显微组织的影响

用粉末冶金法制备了6种Sm(CobalFe0.1CuyZr0.04)z烧结磁体,每种成分磁体都进行了热处理工艺优化实验;并对合金成分对磁体的显微组织及磁性能的影响进行了研究.结果表明z值较小的磁体有较多的15相,室温的Br、Hα与(BH)max都较低些,但方形度(K)较好,因此适当减小z值有利于提高高温磁性能;Cu含量的增加使15相的畴壁能(γ5)减少,217相与15相的畴壁能差(△γ)增加,从而使矫顽力增加,但Cu含量太高,如果不同时增加Sm含量,将导致Br与(BH)max急剧下降;z值较低,同时Cu含量又较高的Sm(CobalFe0.1-Cu0.16Zr0.04)6.7磁体具有最佳室温磁性能与方形度.     

高温2∶17型SmCo永磁体的显微组织及其与磁性能的关系

为了解2∶17型SmCo永磁体的显微组织与磁性能的关系,用粉末冶金法制备了4种Sm(CobalFe0.1-CuyZr0.04)z烧结磁体,每种成分磁体都进行了热处理工艺优化实验;并对磁体的显微组织及其与磁性能的关系进行了研究。结果表明:z值较低,同时Cu含量又较高的Sm(CobalFe0.1Cu0.16Zr0.04)6.7磁体具有最佳磁性能;扫描电镜(SEM)观察表明:显微组织表现为晶粒细小均匀且基本没有孔洞,晶界析出物均匀平滑地沿晶粒边界析出、且不成大块聚集的磁体具有较好的磁性能;磁力显微镜(MFM)观察表明:Sm(CobalFe0.1Cu0.16Zr0.04)6.7磁体的显微组织呈明显的胞状结构,磁畴结构表现为波纹畴结构,其高温磁滞回线在400℃时方形度仍较好,Hci仍有830kA/m,矫顽力温度系数(β)达-0.15%/℃,在500℃时退磁曲线才开始恶化。     

合金成分对高温Sm(Co,Fe,Cu,Zr)z磁性能与显微组织的影响

用粉末冶金法制备了6种Sm(CobalFe0.1CuyZr0.04)z烧结磁体,每种成分磁体都进行了热处理工艺优化实验;并对合金成分对磁体的显微组织及磁性能的影响进行了研究。结果表明:z值较小的磁体有较多的1∶5相,室温的Br、Hci与(BH)max都较低些,但方形度(K)较好,因此适当减小z值有利于提高高温磁性能;Cu含量的增加使1∶5相的畴壁能(1γ∶5)减少,2∶17相与1∶5相的畴壁能差(Δγ)增加,从而使矫顽力增加,但Cu含量太高,如果不同时增加Sm含量,将导致Br与(BH)max急剧下降;z值较低,同时Cu含量又较高的Sm(CobalFe0.1-Cu0.16Zr0.04)6.7磁体具有最佳室温磁性能与方形度。     

2∶17型Sm-Co高温永磁体的研究

用粉末冶金工艺制备了Sm(CobalFevCu0 .0 88Zr0 .0 2 5) 7.5(v =0～ 0 .3 0 )烧结磁体 ,通过系统研究Fe含量对磁体的室温及高温磁性的影响 ,制备出了具有很好的高温稳定性的永磁材料Sm(CobalFe0 .0 7Cu0 .0 88Zr0 .0 2 5) 7.5,在 5 0 0℃时其磁性能为 :Br=0 .687T ,bHC=42 9.7kA·m- 1 ,iHC=63 7 4kA·m- 1 ,(BH) max=83 .7kA·m- 1 。比较了该材料与商业用高矫顽力Nd Fe B和高矫顽力 2∶17型Sm Co磁体的高温磁性。     

2:17型Sm(CoCuFeZr)_z永磁合金的高性能化研究进展

2∶17型Sm(CoFeCuZr)_z永磁合金因其磁性能良好、居里温度高、温度稳定性强、抗腐蚀和抗氧化性强等优点,满足了航空航天、军事等高温工作环境的使用要求,已成为高温永磁材料的最佳选择。近年来,随着更高使用温度的应用需求和电动车高温磁体的开发, 2∶17型SmCo永磁体的相关研究重新引起重视。通常,获得较高室温磁性能及高温稳定性的重要因素是拥有高剩磁、高室温矫顽力和低温度系数。相应的,提高磁体磁性能的有效方法主要包括提高Fe含量、优化磁体中Cu元素的含量及分布及掺杂重稀土元素等等。在先前的研究中,主要关注Sm(CoFeCuZr)_z磁体晶粒内纳米级的微观结构的演化,鲜有关于磁体晶界研究的报道。本文就Sm(CoFeCuZr)_z磁体相关工作在近期取得的进展进行回顾,并介绍了元素含量变化引起的结构、磁性能变化及调控方法,磁体晶界Cu元素分布状态对磁性能的影响方式,以及通过掺杂技术改善Sm(CoFeCuZr)_z磁体晶界结构缺陷,最终实现磁体磁性能的优化。     

高温稀土永磁Sm2(Co,Cu,Fe,Zr)17的研制

利用粉末冶金方法研制了Sm(CobalFe0.24Cu0.08Zr0.027)7.0,Sm(CpbalFe0.27Cu0.05Zr0.027)7.0,Sm(CobalFe0.26Cu0.05Zr0.026)7.0 3种高温永磁,并对其磁性能、温度稳定性和显微结构进行了分析.结果表明:样品Sm(CobalFe0.27Cu0.05Zr0.027)7.0具有最高的内禀矫顽力(2 165.6 kA·m-1)和最大磁能积(212.0kA·m-3);3种磁体的温度系数都较低,最高使用温度均在400℃以上,大大高于一般商用磁体;增加Sm,Co,Cu的含量和减少Fe的含量可以提高材料的温度稳定性.X射线分析表明,合金中含有Sm2(Co,Fe)17主相,Sm(Co,Cu)5相,含Zr化合物等.Sm(Co,Cu)5相、单质Zr、晶粒边界等钉扎畴壁,使合金具有较高的矫顽力.     

低温度系数稀土永磁体的研究

研究了具有较低温度系数的稀土永磁体,包括低矫顽力温度系数的Nd2Fe14B/Fe3B-ferrite复合粘结磁体和低剩磁温度系数的Sm0.8RE0.2(CobalFe0.22Cu0.06Zr0.03)7.4(RE为Gd,Er)烧结磁体.实验表明,添加矫顽力温度系数βjHc为正数的铁氧体磁粉可将粘结磁体的矫顽力温度系数值减小.还讨论了固溶处理对2∶17型Sm-Co烧结磁体磁性能的影响以及添加重稀土元素部分替代钐,对提高温度稳定性的作用.     

烧结温度对高矫顽力Sm2(Co,Fe,Cu,Zr)17永磁体磁性能的影响

为深入了解高矫顽力Sm2(Co,Fe,Cu,Zr)17永磁体烧结温度与磁体磁性能的关系，设计了6种不同烧结温度，分别测试了各温度下烧结试样的密度和磁性能。试验结果表明：高矫顽力Sm2(Co,Fe,Cu,Zr)17磁体的密度随着烧结温度的升高而升高，在1210－1220℃达到最大值；磁体在1205－1210℃烧结时有较高的磁性能，内禀矫顽力超过1910kA/m，最大磁能积达到210kJ/m^3，温度过高或过低都使磁本性能下降；剩磁Br随磁体密度的升高而上升，矫顽力Hci的变化是密度和晶粒大小及胞状尺寸综合作用的结果。     

Antioxidation Study of Sm（Co, Cu, Fe, Zr）z-Sintered Permanent Magnets by Metal Injection Molding

2∶17type Sm(Co ,Cu ,Fe ,Zr)zpermanent mag-nets originatedfromthe investigationinthe 1970s .Sm(Co ,Cu ,Fe ,Zr)zpermanent magnets have excellentintrinsic magnetic properties such as very high Curietemperature , high anisotropy fields , and relativelyhigh saturation magnetizations[1 ~4]. Hence the mag-nets play an i mportant role in national defence andmodernindustry .Because of the high brittleness of Sm(Co ,Cu ,Fe ,Zr)zpermanent magnets ,theirtransfor-mationinto complex,small ,precision …     

Application of high-temperature permanent magnets Sm(Co, Fe, Cu, Zr)z in PPM focusing system

Rare earth permanent magnets Sm(Co, Fe, Cu, Zr)z with outstanding performance and high-temperture thermal stability were fabricated. Optimized by Fe content and process, Sm(Co0.72Fe0.1Cu0.1Zr0.03.03)7.5 magnet with Br>0.75 T and Hci>1300 kA/m at 300 ℃ can be obtained. According to the performance data of Sm(Co0.72Fe0.15Cu10.1Zr0.03)75, the magnetic field along central axis BZ in periodic permanent magnet (PPM) focusing system was simulated using electromagnetic field analysis software Maxwell 2D/3D. The BZ exhibited typical cosine curve along central axis, and the peak value of BZ was high enough to meet the demand of PPM focusing system at room temperature even at 200±20 ℃. Additionally, a kind of simple cooling structure for PPM focusing system was designed by setting cooling pipe between polepieces.Simulated results showed that smooth cosine curve of BZ was successfully achieved with good control of the thickness of cooling pipe.     

Effects of copper and zirconium contents on microstructure and magnetic properties of Sm(Co,Fe,Cu,Zr)_z magnets with high iron content

The evolution of the microstructure,microchemistry and magnetic properties of the Sm(Co_(bal)Fe_(0.28)-Cu_yZr_x)_(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(Co_(bal)Fe_(0.28)Cu_yZr_(0.02))_(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 2 5.4 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.     

Magnetic Microstructures of 2:17 Type Sm(Co,Fe,Cu,Zr)z Magnets Detected by Magnetic Force Microscopy

The magnetic microstructures of 2:17 type Sm(Co,Fe,Cu,Zr)z magnets were detected by magnetic force microscopy.Comparing the microstructures of the specimens coated with and without Ta thin film before and after heat-treatment, it is found that: (a) as a protection layer, Ta coating layer about 20 nm thick can effectively restrain Sm volatilization under high temperature;(b) the stress built in the 2:17 type Sm-Co magnets during specimen preparation only affects some local parts of the domain structures;(c) the magnetic microstructures vary largely for specimens heat-treated at high temperature without Ta film coating due to Sm volatilization.In addition, by comparing with high coercivity Fe-Pt point tips, it is found that the Co-Cr thin-film tips are not suitable for detecting the magnetic microstructures of strong permanent magnets.     

Magnetic Microstructures of 2：17 Type Sm（Co,Fe,Cu,Zr）z Magnets Detected by Magnetic Force Microscopy

The magnetic microstructures of 2：17 type Sm （Co, Fe, Cu, Zr）z magnets were detected by magnetic force microscopy. Comparing the microstructures of the specimens eoated with and without Ta thin film before and after heat-treatment, it is found that： （a） as a protection layer, Ta coating layer about 20 nm thick can effectively restrain Sm volatilization under high temperature; （b） the stress built in the 2.17 type Sm-Co magnets during specimen preparation only affects some local parts of the domain structures; （c） the magnetic microstructures vary largely for specimens heat-treated at high temperature without Ta film coating due to Sm volatilization. In addition, by comparing with high coercivity Fe-Pt point tips, it is found that the Co-Cr thin-film tips are not suitable for detecting the magnetic microstructures of strong permanent magnets.     

温度对2:17型SmCo永磁材料磁性能的影响

研究了Sm_2(Co Cu Fe zr)_(17),材料的剩磁B_r,、内禀矫顽力iH_c随温度的变化关系,研究了材料在不同温度条件下的磁通可逆损失和不可逆损失,随着材料内禀矫顽力iH_c的增大,可逆损失和不可逆损失都明显减小,最后采用了畴壁位移理论解释了磁性能随温度衰变的机制,提高材料的内禀矫顽力是提高材料温度稳定性的有效途径。     

Rare earth permanent magnets Sm2(Co,Fe,Cu,Zr)17 for high temperature applications

Sintered Sm(CobalFexCu0.1Zr0.03)7.5 (x=0.09-0.21) permanent magnets with higher Fe content were found to have higher remanence Br and maximum energy product (BH)max at room temperature. Br and (BH)max reached maximum of 0.96 T and 176.7 kJ/m3, respectively at room temperature when the Fe content x reached 0.21. However, the intrinsic coercivity Hci at room temperature increased gradually when the Fe content x increased from 0.09 to 0.15, but when x further increased to 0.21, Hci decreased. Hci attained its peak value of 2276.6 kA/m with Fe content x=0.15 at room temperature. For magnets with x=0.15, Br, (BH)max and Hci reached 0.67 T, 81.2 kJ/m3 and 509.4 kA/m at 500℃, respectively, showing good high temperature stability, which could be used in high temperature applications.     

Sm2(Fe,M)17Nx稀土永磁材料的研究进展

综述了Sm2(Fe，M)17Nx永磁材料的最新研究进展，介绍了Sm2(Fe，M)17Nx磁粉及磁体的制备技术，说明用其他元素替换Sm或Fe对材料性能的影响，以及粉末颗粒具有最佳的尺寸和形貌的重要性。并指出放电等离子烧结技术(SPS)有望成为制备Sm2(Fe，M)17Nx致密磁体的一个有效方法。     

双相纳米晶Nd2Fe14B/α-Fe磁体的热稳定性研究

采用快淬法制备出成分为Nd8.5Fe75Co5Cu1 Zr3Nb1 B6 .5和Nd8.5Fe74 Co5Cu1 Nb1 Zr3Cr1 B6 .5的双相纳米晶永磁材料 ,加入粘结剂后制成粘结磁体 ,研究了其磁性的热稳定性和抗氧化性能。结果发现 ,两种双相纳米晶磁体都具有较好的抗氧化性能 ,且在一定温度处理后磁通损耗较少 ,其中加入合金元素Cr后效果尤为明显。     

利用粉末掺和技术生产(Nd,Mm)2(Fe,Co,Ni)14B型烧结磁体

概述了利用粉末掺和技术制得（Nd，Mm）2（Fe，Co，Ni）14B型各项异性磁体的基本情况及该材料的主要性能。