Short range order transformation and magnetostriction of Fes3Ga17 ribbons

The relationship between magnetostriction and structure of melt-spun Fes3Ga17 ribbons are investigated by XRD and M5ssbauer spectrum technique （MS）. As the heat-treatment temperature increases from 650℃ to 800℃, the magnetostriction coefficient of Fes3Ga17 ribbon first increases and then decreases. The largest magnetostriction coeiffcient （-578.4 ppm） is achieved in those specimens quenched at 750oc. According to the XRD and MSssbauer spectrum anal- ysis, a small quantity of DO3 phase is precipitated in Fe83Ga17 ribbons when quenched from 650℃ and the DO3 phase is gradually transformed into B2-1ike phase if quenched at higher temperature. However, both DO3 and B2-1ike phases disappear when the temperature increases up to 800℃. From this point of view, B2-1ike phase might be beneficial to the enhancement of magnetostrictive properties of melt-spun ribbons.     

烧结Nd-Fe-B磁体表面渗镀Dy2O3对磁体显微组织和磁性能的影响

研究了烧结Nd-Fe-B磁体表面渗镀Dy2O3对磁体组织结构与磁性能的影响. 表面渗镀Dy2O3后, N40的矫顽力由1017 kA · m-1提高到1146 kA · m-1, 38H的矫顽力由1575 kA · m-1提高到1753 kA · m-1, 而通过传统合金化添加同量Dy, N40和38H的矫顽力分别为1061和1634 kA · m-1. 磁体表面渗镀Dy2O3后热稳定性也大大改善. 组织分析表明, 元素Dy从表面扩散并渗入磁体的内部约20 μm厚, Nd2Fe14B晶粒表层附近Dy含量比晶界中高, 说明Dy2O3中的Dy通过扩散与富Nd相及Nd2Fe14B晶粒表面层的部分Nd发生置换反应, 增强了Nd2Fe14B晶粒表面层的磁晶各向异性. 在此基础上, 提出了高矫顽力高热稳定性渗Dy的烧结Nd-Fe-B磁体中Dy分布的理想模型.     

Short range order transformation and magnetostriction of Fe83Ga17 ribbons

The relationship between magnetostriction and structure of melt-spun Fe 83 Ga 17 ribbons are investigated by XRD and M¨ossbauer spectrum technique(MS).As the heat-treatment temperature increases from 650℃ to 800℃,the magnetostriction coefficient of Fe 83 Ga 17 ribbon first increases and then decreases.The largest magnetostriction coefficient(578.4 ppm) is achieved in those specimens quenched at 750℃.According to the XRD and Mo¨ssbauer spectrum analysis,a small quantity of DO 3 phase is precipitated in Fe 83 Ga 17 ribbons when quenched from 650℃ and the DO 3 phase is gradually transformed into B2-like phase if quenched at higher temperature.However,both DO 3 and B2-like phases disappear when the temperature increases up to 800℃.From this point of view,B2-like phase might be beneficial to the enhancement of magnetostrictive properties of melt-spun ribbons.     

Wiedemann effect of Fe—Ga based magnetostrictive wires

(Fe83Ga17)98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly,because the ductility of Fe83Ga17 alloy is improved by adding Cr element.The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and(Fe83Ga17)98Cr2 wires are investigated.The largest observed Wiedemann twists of 245 s·cm-1 and 182 s·cm-1 are detected in the annealed Fe83Ga17 and(Fe83Ga17)98Cr2 wires,respectively.The magnetostrictions of the annealed Fe83Ga17 and(Fe83Ga17)98Cr2 wires are 160 ppm and 107 ppm,respectively.The maximum of the Wiedemann twist increases with magnetostriction increasing.However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire,and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.     

《113》轴向取向稀土超磁致伸缩材料的制备与性能

利用低温度梯度水平炉, 成功地生长了113轴向取向的稀土超磁致伸缩材料, 该材料在低磁化场下具有很高磁致伸缩应变, 在10 MPa压应力、 80 kA*m-1磁场下的磁致伸缩应变λ=1540×10-6. 113轴向取向材料的高磁致伸缩应变来源于材料良好的取向; 定向生长的大晶粒; 施加磁场时较多的可转动磁矩.     

Tb1-xPrxFe1.96 (x=0,0.1,...,0.7)化合物的磁性能及其物相组成的研究

研究了名义成分为Tb1-xPrxFe1.96 (x=0, 0.1, ..., 0.7)化合物的磁性能及其物相组成. 研究发现, 随着Pr含量的上升, 化合物在易磁化方向的饱和磁化强度先下降后上升, 从x=0的77.24 Am2·kg-1, 下降到x=0.5的最低值11.84 Am2·kg-1, 再回复到x=0.7的37.14 Am2·kg-1; 在x=0.2时化合物开始出现非立方相结构; 化合物主相从x=0时的1:2相过渡为x=0.4时的1:3相, 最后变为x=0.7时的2:17相. 而且Pr的含量越高, 化合物的物相组成就越复杂.     

巨磁致伸缩合金Tb-Dy-Fe近似单晶颗粒在磁场中的取向

主要研究了TbxDy1-xFey(0.27≤x≤0.50,y≈1.95)退火合金粉末的近似单晶颗粒,在磁场中的取向情况,及其与成分x,颗粒的粒度,有机胶比,取向场,取向温度等之间的关系.观察到在x为0.295与0.33之间,取向效果有很大的差异.并对取向效果与上述各因素之间的关系进行了讨论.     

热处理工艺对〈110〉轴向取向Tb-Dy-Fe合金性能与显微组织的影响

研究了热处理工艺对<110>轴向取向Tb0.3Dy0.7(Fe1-xMx)1.95(M=Mn,Al,Ti,B,x=0.03)合金磁致伸缩性能与显微组织的影响。实验结果表明,热处理后合金的磁致伸缩应变λ和dλ/dH都显著提高,显微组织由片状晶向多边形晶粒转化,而且富稀土相在样品表面和晶界析出,晶粒内部的富稀土相有球化趋势。合理控制热处理温度和时间可以显著提高该合金的磁致伸缩性能。