用磁力显微镜研究了三元Nd Fe B合金在HDDR过程的不同阶段(铸态、不充分吸氢歧化、充分吸氢歧化和脱氢再复合)的磁畴结构。在铸态样品表面清楚地观察到了易磁化轴互相垂直的柱状晶表面的两类磁畴图型。当样品不充分吸氢歧化和充分吸氢...用磁力显微镜研究了三元Nd Fe B合金在HDDR过程的不同阶段(铸态、不充分吸氢歧化、充分吸氢歧化和脱氢再复合)的磁畴结构。在铸态样品表面清楚地观察到了易磁化轴互相垂直的柱状晶表面的两类磁畴图型。当样品不充分吸氢歧化和充分吸氢歧化时,磁畴结构明显发生变化,反映了Nd Fe B的分解产物NdH2,α Fe和Fe2B及其微晶结构的变化。脱氢再复合后形成的微晶的磁畴结构则表明样品保留了铸态样品柱状晶的构型。此外,还对比研究了多元Nd Fe B合金在HDDR过程中的磁畴结构,并根据微磁结构分析,指出过量的Ga元素添加可抑制Nd2(Fe,M)14B相的吸氢歧化,从而导致相应HDDR粘结磁体性能降低。展开更多
XRD,SEM及MFM观察表明,Nd Fe B粉末压坯在液相烧结过程中同时存在两种影响主相晶粒取向度的机制:烧结过程中大颗粒吞并吸附在其表面的取向不良的小晶粒并择优长大,使磁体的取向度提高;在液相烧结过程中,被液相所包围的主相晶粒的自由转...XRD,SEM及MFM观察表明,Nd Fe B粉末压坯在液相烧结过程中同时存在两种影响主相晶粒取向度的机制:烧结过程中大颗粒吞并吸附在其表面的取向不良的小晶粒并择优长大,使磁体的取向度提高;在液相烧结过程中,被液相所包围的主相晶粒的自由转动,造成磁体的取向度降低。对于取向度较低的DP生坯,烧结中影响Nd Fe B磁体取向度的前一种机制是主导的;而对于取向度较高的振动RIP生坯,烧结过程中后一种机制起主导作用。展开更多
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 afte...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.展开更多
The aexercisegexperiment shows that the dumbbell domains,which can eventually contract to circular form and then collapse,should be classified as a kind of dumbbells rather than hard bubbles.Thus dumbbell domains can ...The aexercisegexperiment shows that the dumbbell domains,which can eventually contract to circular form and then collapse,should be classified as a kind of dumbbells rather than hard bubbles.Thus dumbbell domains can be divided into two kinds:ID and HD.Their static characteristics are reported,and typical photos are presented.展开更多
The typical magnetic domains of Sm（CObalFe0.25Cuo.07Zr0.02）7.4 magnets quenched through various heattreatment steps have been revealed by using magnetic force microscopy （MFM）. For the specimens in which the nomin...The typical magnetic domains of Sm（CObalFe0.25Cuo.07Zr0.02）7.4 magnets quenched through various heattreatment steps have been revealed by using magnetic force microscopy （MFM）. For the specimens in which the nominal c-axis is perpendicular to the imaging plane, the domain configurations change from plate-like for the as-sintered magnet to corrugation and spike-like for the homogenized one, and then to a coarse and finally to a finer domain structure when isothermally aged at 830℃ and then annealed at 400℃. However, only plate-like domains can be detected on the surfaces with the nominal c-axis parallel to the imaging plane. The finer domain （so-called interaction domain） is a characteristic magnetic domain pattern of the SmCo 2：IT-type magnets with high coercivities. Domain walls in a zigzag shape are revealed by means of MFM in final bulk SraCo 2：17-type sintered magnets.展开更多
We present a magnetic force microscopy study of surface magnetic microstructure changes at high temperatures in 2：17-type Sm（Co,Fe, Cu,Zr）z （z ～ 7.4） magnets. Surface magnetic microstructures are found to change...We present a magnetic force microscopy study of surface magnetic microstructure changes at high temperatures in 2：17-type Sm（Co,Fe, Cu,Zr）z （z ～ 7.4） magnets. Surface magnetic microstructures are found to change greatly in parallel and vertical specimens after heat-treatment at 400℃ for one hour in vacuum of 10^-5 Torr with Ar gas as protecting atmosphere. Changes of microstructures are attributed to the formation of a soft-magnetic surfaces layer in the specimens, resulting from Sm volatilization due to high temperature. This hypothesis is further confirmed by the heat-treatment experiments at 400℃ for 0.5 h and 2 h. Finally, the existence of the soft-magnetic layers, which consist primarily of Fe Co compounds, is verified by the results of both XRD and XPS of the vertical specimens before and after heat-treatment.展开更多
文摘用磁力显微镜研究了三元Nd Fe B合金在HDDR过程的不同阶段(铸态、不充分吸氢歧化、充分吸氢歧化和脱氢再复合)的磁畴结构。在铸态样品表面清楚地观察到了易磁化轴互相垂直的柱状晶表面的两类磁畴图型。当样品不充分吸氢歧化和充分吸氢歧化时,磁畴结构明显发生变化,反映了Nd Fe B的分解产物NdH2,α Fe和Fe2B及其微晶结构的变化。脱氢再复合后形成的微晶的磁畴结构则表明样品保留了铸态样品柱状晶的构型。此外,还对比研究了多元Nd Fe B合金在HDDR过程中的磁畴结构,并根据微磁结构分析,指出过量的Ga元素添加可抑制Nd2(Fe,M)14B相的吸氢歧化,从而导致相应HDDR粘结磁体性能降低。
文摘XRD,SEM及MFM观察表明,Nd Fe B粉末压坯在液相烧结过程中同时存在两种影响主相晶粒取向度的机制:烧结过程中大颗粒吞并吸附在其表面的取向不良的小晶粒并择优长大,使磁体的取向度提高;在液相烧结过程中,被液相所包围的主相晶粒的自由转动,造成磁体的取向度降低。对于取向度较低的DP生坯,烧结中影响Nd Fe B磁体取向度的前一种机制是主导的;而对于取向度较高的振动RIP生坯,烧结过程中后一种机制起主导作用。
文摘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.
文摘The aexercisegexperiment shows that the dumbbell domains,which can eventually contract to circular form and then collapse,should be classified as a kind of dumbbells rather than hard bubbles.Thus dumbbell domains can be divided into two kinds:ID and HD.Their static characteristics are reported,and typical photos are presented.
基金Project supported by the Beijing Municipal Science and Technology Committee Key Project, China (Grant No D0406002000091)the National Natural Science Foundation of China (Grant No 10374110)
文摘The typical magnetic domains of Sm（CObalFe0.25Cuo.07Zr0.02）7.4 magnets quenched through various heattreatment steps have been revealed by using magnetic force microscopy （MFM）. For the specimens in which the nominal c-axis is perpendicular to the imaging plane, the domain configurations change from plate-like for the as-sintered magnet to corrugation and spike-like for the homogenized one, and then to a coarse and finally to a finer domain structure when isothermally aged at 830℃ and then annealed at 400℃. However, only plate-like domains can be detected on the surfaces with the nominal c-axis parallel to the imaging plane. The finer domain （so-called interaction domain） is a characteristic magnetic domain pattern of the SmCo 2：IT-type magnets with high coercivities. Domain walls in a zigzag shape are revealed by means of MFM in final bulk SraCo 2：17-type sintered magnets.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10374110 and 50201004.
文摘We present a magnetic force microscopy study of surface magnetic microstructure changes at high temperatures in 2：17-type Sm（Co,Fe, Cu,Zr）z （z ～ 7.4） magnets. Surface magnetic microstructures are found to change greatly in parallel and vertical specimens after heat-treatment at 400℃ for one hour in vacuum of 10^-5 Torr with Ar gas as protecting atmosphere. Changes of microstructures are attributed to the formation of a soft-magnetic surfaces layer in the specimens, resulting from Sm volatilization due to high temperature. This hypothesis is further confirmed by the heat-treatment experiments at 400℃ for 0.5 h and 2 h. Finally, the existence of the soft-magnetic layers, which consist primarily of Fe Co compounds, is verified by the results of both XRD and XPS of the vertical specimens before and after heat-treatment.
