【作者】 刘何燕；

【导师】 李养贤； 吴光恒； 王荫君；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2002， 硕士

【摘要】 本文对含轻稀土磁致伸缩材料及MnBiAl薄膜的制备及性能进行了研究。 鉴于稀土化合物凝固结晶的特点，对区熔法进行了改进，将电弧炉熔炼好的样品装入石英管中，封石英管后在区熔设备上进行区熔。对于石英管的直径、装入石英管块材的大小及区熔工艺参数等因素进行了分析。采用电弧炉熔炼的方法制备了Ce_x(Tb_0.27Dy_0.73)_1-xFe₂和Pr_0.15Tb_xDy_0.85-xFe₂系列的合金，对于X光结构、晶格常数、居里温度及磁致伸缩性能进行了分析。研究结果表明，在Ce_x(Tb_0.27Dy_0.73)_1-xFe₂体系中，Ce的价态是向+3价态波动的，Ce_x(Tb_0.27Dy_0.73)_1-xFe₂合金的磁致伸缩随x的增加而下降。对于Pr_0.15Tb_xDy_0.85-xFe₂系列合金，由于Pr的替代，磁晶各向异性补偿点由x=0.27移到x=0.3，当磁场为20KOe时，磁致伸缩由Tb_0.27Dy_0.73Fe₂的1600ppm提高到2100ppm。采用改进的区熔法制备出主要以＜110＞的Pr_0.15Tb_0.3Dy_0.55Fe₂棒材，磁场为900KA／m时，磁致伸缩达到1000ppm。尽管棒材仅为φ79×30mm，然而通过改进工艺条件，有望获得更大的棒材及＜211＞甚至＜111＞取向的棒材。 采用粘结法制备了Th_0.27Dy_0.73Fe₂粘结体，研究了胶量，成形压力对粘结体电阻率，密度及磁致伸缩性能的影响。结果表明，密度随成形压力的增加而增加，电阻率则随成形压力的增加而减小，在48MPa～148MPa内，成形压力对磁致伸缩性能的影响不大。胶与磁性粉末的质量比为4：100时，粘结体的密度最高，电阻率最低，磁致伸缩性能最佳。在磁致伸缩的测量中，预应力可大大提高粘结棒材的磁致伸缩，当预应力为10MPa时，粘结棒材在磁场为450kA／m时达到1186ppm。采用粘结法制备的Pr_0.15(Tb_0.35Dy_0.65)₍0.85_Fe₂棒材，当磁场为900kA／m，磁致伸缩达900ppm。采用Al作为粘结剂，得到了结构致密的粘结体，粘结体的轴向磁致伸缩达到350ppm。 本文采用溅射法制备出结构完整的＜002＞取向的MnBiAl薄膜。对溅射Bi薄膜在不同基片上的结构及溅射MnBiAl薄膜结构和性能进行了研究。研究表明，在＜100＞取向的SrTiO₃基片上，溅射Bi薄膜主要以＜003＞取向，而在玻璃基片上，溅射Bi薄膜无取向。对Mn：Bi原子比（Al含量一定）及多层膜周期数（总厚度一定）对溅射MnBiAl薄膜结构影响的研究表明，当Al的含量一定，Mn：Bi原子比为1：0.92时，可制备出结构完整的MnBiAl薄膜，总厚度不变的情况下，单周期MnBiAl比双周期的MnBiAl具有更强的＜002＞取向结构。低温转矩测量表明，溅射MnBiAl薄膜在80K主要是垂直膜面各向异性。更多还原

【Abstract】 In this work, the preparation and properties of magnetostrictive material and MnBiAl thin film are studied.On account of the solidification character of rare earth alloys, the zone melting is improved by putting the alloys prepared by arc-melting into the quartz tube, then melting. The technological parameters such as the diameter of quartz tube, the dimension of materials and parameters in zone melt are analyzed. Ingots of Cex(Tbo.27Dyo.73)i-xFe2 and Pro.i5TbxDyo.85-xFe2 alloys is prepared by arc-melting in a cold copper crucible under an argon atmosphere protection. The lattice constant, courier temperature and magnetostrictin of Cex(Tbo.27Dyo.73)i-xFe2 and Pro.i5TbxDyo.8s-xFe2 alloys is studied. It is shown that, in Cex(Tbo.27Dyo.73)i-xFe2 alloys, the valence of Ce is moved to +3 with the Ce increasing, the magnetostriction of Cex(Tbo.2?Dyo.73)i-xFe2 alloys is decreased with Ce increasing. In Pro.i5TbxDyo.g5-xFe2 alloys, due to the Pr as substitute for Tb, the point of the lowest magneto-crystalline anisotropy is shifted to 0.3, the magnetostriction of Pro.i5Tbo.3Dyo.5sFe2 alloys is SOOppm higher than Tbo.27Dyo.73Fe2 alloys at 20KOe. The Pro.i5Tbo.3Dyo.5sFe2 stick orienting by <110> is prepared by improving zone melting. Although the dimension is only $ 7.9 X 30mm, the more bigger and oriented by <211> or <111> will be prepared by adjusting technological parameters.The Terfenol-D and Pro.i5TbojDyo.55Fe2 composite is prepared by polymer-bonding method. The influence of the proportion of binder and compaction pressure on the density, resistivity and magnetostriction of the bonded composites have been investigated. It was found that the sample density increases with the increasing compaction pressure, while the resistivity decrease with the increasing compaction pressure. The compaction pressure between 48MPa and 148MPa has a little effect on the magnetostriction. The highest density and the low resistivity and the best magnetostriction in a composite rod were obtained when the proportion of binder to powders’ weight is 4:100. The large magnetostriction of 1186xlO"6 at 450KA/m for Terfenol-D composite with the applied compressive stress of lOMPa and magnetostriction of 900x10"6 at 900KA/m for Pro.isTbojDyo.ssFea composite are obtained. The magnetostriction of 350ppm for the bonded composite with Al as binder at 900KA/m is obtained.MnBiAl thin film orienting by <002> is prepared by sputtering. The structure of Bi film and MnBiAl film is investigated. It is shown that Bi film on SrTiC>3 substrate orienting in <100> is mainly oriented in <003>, while Bi film on glass substrate is disoriented. The study of the Mn:Bi influence on the structure of MnBiAl film shows that ,on the base of the same Al content , only the specimen with Mn:Bi 1:0.92 possesses single phase structure of MnBiorienting in <002>. With the whole thickness fixed, the structure of sole layer specimen [Bi/Al/Mn] is more integral than that of double layers specimen [Bi/Al/Mn/Bi/Al/Mn]. The measurement of MnBiAl torque at low temperature shows that MnBiAl film possesses a perpendicular magnetic anisotropy with decreasing temperature down to 80K.更多还原