超磁致伸缩材料作为一种新型功能材料，受到世界高技术领域专家们的极大关注，发展迅速。美国、日本、瑞士等国家对其制备工艺、成分、相结构、和性能做了大量研究工作，开发了许多实用器件，如传感器、致动器和换能器等。我国在该领域仍然存在一些尚需研究与完善的课题，如材料的性能不及国外产品且不稳定，某些方面的研究有待继续深入等。
本文通过添加微量稀土Ho对稀土超磁致伸缩合金进行改性研究，探讨提高材料性能的途径。实验采用真空非自耗电弧熔炼法制造Tb0.3Dy0.7(Fe1-xHox)1.95。系统研究了室温下Tb0.3Dy0.7(Fe1-xHox)1.95(x=0,0.05,0.1,0.15,0.2,0.25)合金中金属Ho替代Fe对晶体结构、磁致伸缩等的影响。并对退火后出现的蘑菇状生长物进行了分析讨论。
通过研究分析，论文得出如下结论：
(1)稀土Ho的添加对磁致伸缩性能有很大的影响，随着Ho含量的增加，掺Ho在原子比为0.2时达到最小值209.8ppm，含量为0.25时， 达最大值538.8ppm；
(2)Terfenol-D超磁致伸缩材料在高温退火过程中长出的蘑菇为多相，合金和蘑菇相比，合金的组织疏松，蘑菇由于含有过多的富稀土相和其他杂质而组织致密；
(3)高温退火组织转变的同时还发生传质过程，这时进行着相辅相成的两个重要程：富稀土相熔化后通过晶界管道被挤出，基相枝晶则转变为粗大的柱状晶；
机械毕业论文----德维在线 www.devay.net
(4)退火过程中充分进行传质和组织转变是获得具有高磁致伸缩性能GMM棒的必要条件，蘑菇的出现是其重要标志。
关键词：稀土Ho；磁致伸缩；制备技术；“蘑菇”状析出物
Abstract
Experts in high-tech domain all over the world have followed rare earth giant magnetostrictive materials,a modern functional material, with interest.In U.S.A.、Japan,、Switzerland,etc.,the studies were carried out on preparation, composition, phase structure, properties and so on. A large amount of practical devices, such as sensor, actuator, transducer etc. were developed. Our country still had the topic in this domain which some still had to study and to consummate, like the material performance was inferior to the overseas product also was unstable, certain aspect research pending continued and so on thoroughly.
This article conducts the modified research through increase micro rare earth Ho to the rare earth giant magnetostriction alloy, the discussion enhances the material performance the way. The experiment uses the vacuum must from to consume the electric arc smelting law manufacture Tb0.3Dy0.7(Fe1-xHox)1.95.The effect of Ho substitution for Fe on the structure, magnetostriction, and anisotropy of a series of Tb0.3Dy0.7(Fe1-xHox) 1.95 alloys(x=0, 0.05, 0.1,0.15, 0.20, 0.25,) at room temperature has been investinated. And the mushroom-shaped which appears after the annealing lives the surplus to carry on the analysis discussion.
英语毕业论文----德维在线 www.devay.net
Through the research analysis, the paper draws the following conclusion:
（1）The rare earth Ho increase has the very tremendous influence to the magnetostriction performance, along with the Ho content increase, mixing Ho achieves minimum value 209.8ppm when the atomic ratio is 0.2 to, when the content is 0.25, reaches maximum value 538.8ppm;
（2）In the Terfenol-D giant magnetostriction material high temperature annealing process, the mushroom created is the heterogeneity, the alloy and the mushroom compares, the alloy organization is loose, as a result of includes excessively many rich rare earth and other impurity organization ,the mushroom is compact;
（3）When high temperature annealing ang structural transformation ,there is the mass transfer process, by now carrying on two important regulations which complemented one another: After the rich rare earth melts is squeezed out through the crystal boundary pipeline, the base arborescent crystal transforms into the thick columnate crystals; 英语专业毕业设计----德维在线 www.devay.net
（4）In the annealing process, carring on the mass transfer and the structural transformation, whice obtaining the high magnetostriction performance GMM stick is essential condition, Mushroom's appearance is its important symbol..
Key word: Rare earth Ho; Magnetostriction; Terfenol-D; Preparation technology; “Mushroom” shape separation