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
本文研究了添加微量元素Si对HDDR工艺制备各向异性Nd Fe Co B Si系永磁磁粉的磁性能和磁粉结构的影响。研究结果表明 :添加Si可以显著地提高磁粉的矫顽力和各向异性 ,Si的添加可以细化晶粒 ,还能使反磁化畴难以形核 ,因而磁粉的矫顽力...本文研究了添加微量元素Si对HDDR工艺制备各向异性Nd Fe Co B Si系永磁磁粉的磁性能和磁粉结构的影响。研究结果表明 :添加Si可以显著地提高磁粉的矫顽力和各向异性 ,Si的添加可以细化晶粒 ,还能使反磁化畴难以形核 ,因而磁粉的矫顽力较高。目前对于添加Si的Nd Fe展开更多
Assuming that intergranular phase (IP) existing between adjacent grains is a weak magnetic phase, we study the effect of IP on the coercivity in the HDDR Nd-Fe-B magnet. The results indicate that the coercivity increa...Assuming that intergranular phase (IP) existing between adjacent grains is a weak magnetic phase, we study the effect of IP on the coercivity in the HDDR Nd-Fe-B magnet. The results indicate that the coercivity increases with the increasing IP’s thickness d, but decreases with increasing its anisotropy constant K1(0). When the structure defect thickness r0 =6nm, d=1nm and K1(0)=0.15K1 (K1 is the normal anisotropy constant in the inner part of a grain), our calculated coercivity is in agreement with available experimental data.展开更多
Effects of alloying additions of Co and Zr on microstructure and magnetic anisotropy of the HDDR powder of Nd Fe B alloy were investigated. It was found that the HDDR powder of Nd Fe Zr B alloy is nearly magnetic...Effects of alloying additions of Co and Zr on microstructure and magnetic anisotropy of the HDDR powder of Nd Fe B alloy were investigated. It was found that the HDDR powder of Nd Fe Zr B alloy is nearly magnetically isotropic, but that of Nd Fe Co Zr B alloy is remarkably anisotropic. A new Zr rich phase is formed in the homogenized Nd Fe Zr B alloy and keeps undecomposing during the HDDR process. The co addition of Co drastically depresses the formation of the Zr rich phase and results in higher Zr content of the hard magnetic phase than in the Co free alloy. The results suggested that a sufficient solubility of alloying elements such as Zr into the hard magnetic phase via the optimization of chemical composition of Nd Fe B alloy is the key for the production of anisotropic Nd Fe B alloy powder by the HDDR process.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Assuming that intergranular phase (IP) existing between adjacent grains is a weak magnetic phase, we study the effect of IP on the coercivity in the HDDR Nd-Fe-B magnet. The results indicate that the coercivity increases with the increasing IP’s thickness d, but decreases with increasing its anisotropy constant K1(0). When the structure defect thickness r0 =6nm, d=1nm and K1(0)=0.15K1 (K1 is the normal anisotropy constant in the inner part of a grain), our calculated coercivity is in agreement with available experimental data.
文摘Effects of alloying additions of Co and Zr on microstructure and magnetic anisotropy of the HDDR powder of Nd Fe B alloy were investigated. It was found that the HDDR powder of Nd Fe Zr B alloy is nearly magnetically isotropic, but that of Nd Fe Co Zr B alloy is remarkably anisotropic. A new Zr rich phase is formed in the homogenized Nd Fe Zr B alloy and keeps undecomposing during the HDDR process. The co addition of Co drastically depresses the formation of the Zr rich phase and results in higher Zr content of the hard magnetic phase than in the Co free alloy. The results suggested that a sufficient solubility of alloying elements such as Zr into the hard magnetic phase via the optimization of chemical composition of Nd Fe B alloy is the key for the production of anisotropic Nd Fe B alloy powder by the HDDR process.
