Fe-Ga磁致伸缩材料研究进展

Fe-Ga合金是人们在新型高性能磁致伸缩材料探索中的一个重要发现,具有高应力灵敏度、良好的热-机械性能和磁致伸缩性能,填补了传统磁致伸缩材料和稀土超磁致伸缩材料之间的空白,在超声领域和微位移器等方面有较大的潜在应用价值,应用前景广阔。本文从Ga含量及相结构、第三组元、制备方法、压力和温度四个部分阐述Fe-Ga磁致伸缩材料的研究进展及研发趋势,总结了Ga含量及相结构、第三组元对Fe-Ga合金的磁致伸缩性能的影响,Fe-Ga合金的磁致伸缩性能与Ga含量密切相关,不同的第三组元对合金磁致伸缩性能的影响也不同;Fe-Ga合金的制备方法主要有定向凝固法、甩带急冷法、轧制法、拉丝法等方法,比较了各种制备方法对材料性能的影响;阐述了应力场和温度对Fe-Ga合金的磁致伸缩性能的影响,其中应力场对Fe-Ga合金的磁致伸缩性能有积极影响,但Fe-Ga合金磁致伸缩的温度依赖性比较复杂,磁致伸缩随温度变化的幅度与趋势都取决于合金结构。     

成分及工艺对SmFe2系磁致伸缩性能的影响

研究了SmFe2合金中不同Sm、Fe比及添加Dy的磁致伸缩性能和力学性能,并且探讨了制备工艺和热处理对合金磁伸性能的影响.结果表明,Sm∶Fe为1∶1.87时,磁致伸缩性能最佳,用部分镝替代钐,可以提高材料的强度,热处理可以明显改善材料的磁致伸缩性能.     

Fe-Ga合金磁致伸缩材料的研究进展

与稀土磁致伸缩材料Tefernol-D相比, Fe-Ga合金具有饱和磁场低、磁导率高、强度高、脆性小和温度特性好等特点, 其潜在的应用范围更为广泛, 尤其适用于强震动、大负荷、强腐蚀等较为恶劣的工作环境. 重点介绍了Fe-Ga磁致伸缩材料的制备工艺、合金成分、微观结构及性能等方面的研究进展.     

新型磁致伸缩合金

美国海军部和衣阿华州大学埃姆斯实验室联合开发了一种新型磁致伸缩合金。磁致伸缩是磁性材料的一种特性,这种特性在磁场作用下引起磁性材料膨胀。当施加有效磁场时,称之为 Terfend-D 的稀土—铁合金(铒—镝—铁)具有任何已知材料的最大室温磁致伸缩性能。在数微秒内10英寸长的棒可     

超磁致伸缩材料的研究新进展

近年来,稀土超磁致伸缩TbDyFe材料的研究进展迅速,既有新的研究方向如材料力学性能、合金的凝固过程、磁畴取向的分布、组分处于准同型相界的合金的性能等,也有传统的如热处理时施加高磁场及应力处理、新热处理方法等方面。此外,科研人员不断开发出新的稀土超磁致伸缩材料合金体系,即不同元素对TbDyFe体系的部分取代与添加,主要有Pr、Nd、Sm、Gd、Ho和Er等稀土元素及第八族的Co元素。     

Terfenol-D材料变负载时的磁致伸缩特性分析

关于稀土超磁致伸缩材料Terfenol-D的磁致伸缩特性国内外已有大量报道,但大多数都是基于载荷(预紧力)在磁致伸缩过程中保持不变条件下的磁致伸缩特性研究。本文在这些研究的基础上分析了Terfenol-D材料在变负载时的磁致伸缩特性,介绍了变负载动态特性曲线的求解方法并讨论了恒载与变载时特性曲线的特点与差异。     

激光多普勒准静态法测量磁致伸缩系数

提出了一种利用激光多普勒测量磁致伸缩系数的方法,理论分析了激光多普勒测量磁致伸缩系数的工作原理,设计了铁镓合金棒材的测试系统.对铁镓合金棒(Galfenol)的准静态磁致伸缩系数进行测量.结果显示,该方法所获得应变与出厂数据符合较好,在10 Hz驱动电流下获得铁镓合金棒的动态变化曲线.该测量方法具有以下优势:(1)能够实现非接触测量;(2)可以测量铁镓合金棒端面任意点的应变情况;(3)测量结果准确度较高;(4)测量操作简单.      

铁镓磁致伸缩材料制备工艺的研究进展

Fe-Ga合金具有原材料成本低、低场高磁致伸缩和高强度等优点,引起材料工作者的广泛关注。介绍了国内外Fe-Ga合金的制备方法、热处理工艺以及添加第三元素等方面的最新研究进展,比较了不同制备方法的优缺点,分析了热处理工艺对合金织构及磁致伸缩性能的影响,提出制备成分均匀、高度取向、大磁致伸缩的Fe-Ga取向织构或单晶材料是未来的研究发展方向。     

微量稀土元素Tb、La掺杂对Fe-Al合金结构和磁致伸缩性能的影响

为了研究微量稀土元素Tb和La掺杂对Fe81Al19合金结构和磁致伸缩性能的影响及影响机制,采用真空电弧熔炼法制备了Fe81Al19、Fe81Al19La0.1和Fe81Al19Tb0.1三种铸态合金。用X射线衍射仪(XRD)和扫描电镜联合能谱仪(SEM/EDS)分析了合金的微结构。用振动样品磁强计(VSM)和磁致伸缩测量仪测试了合金的磁性能和磁致伸缩系数。结果表明,Fe81Al19合金由单一的bcc结构A2相组成,而掺杂稀土后的Fe81Al19Tb0.1和Fe81Al19La0.1合金均由bcc结构的A2主相和少量富稀土相组成。稀土Tb和La的掺杂使Fe81Al19合金沿<100>晶向择优取向,且Fe81Al19Tb0.1合金择优取向更加明显。此外,三种合金的磁化功大小排序为:Fe81Al19Tb0.1> Fe81Al19La0.1> Fe81Al19。表明稀土元素掺杂导致Fe-Al合金具有更大的磁晶各向异性,且Tb的掺杂效果更加明显。磁致伸缩系数测试表明,与Fe81Al19合金相比,稀土掺杂合金的磁致伸缩系数明显增大,而且Fe81Al19Tb0.1合金的磁致伸缩系数增大的更加明显,大约是Fe81Al19合金的3.2倍,为86×10^-6。稀土掺杂合金磁致伸缩系数增大的原因主要源于掺杂稀土使Fe-Al合金沿<100>晶向择优取向和稀土导致合金具有高磁晶各向异性。     

磁场退火对Fe80Si9B11非晶合金的磁致伸缩特性影响

摘要：利用激光多普勒法测量50Hz下非晶合金带材的磁致伸缩曲线,研究了磁场退火对Fe80Si9B11非晶合金带材的磁致伸缩特性的影响。结果显示,在相同的磁场强度下非晶带材经横磁退火后磁致伸缩最大,无磁场退火次之,纵磁退火时最小。然后,采用Kerr方法观察了非晶合金带材的磁畴形貌,从微观结构上解释了经不同磁场退火后磁致伸缩大小不同的机理。最后,对无磁场退火、横磁退火和纵磁退火后的Fe80Si9B11铁基非晶合金铁芯进行了噪音测试。结果显示,在相同的频率和磁通密度下,非晶合金铁芯经横磁退火后噪音最大,无磁场退火次之,纵磁退火时噪音最小,与非晶合金带材经不同磁场热处理后磁致伸缩大小的规律一致。为解决非晶合金铁芯在实际应用中的噪音问题提供了参考。     

Effect of copper on magnetostriction and mechanical properties of TbDyFe alloys

The intrinsic brittleness of the TbDyFe alloy significantly decreases its mach inability and applications.This paper aims to improve the toughness of TbDyFe alloy by adding Cu. Various alloys of the type(Tb_(0.3)Dy_(0.7))_(0.37)Fe_(0.63-χ)Cu_χ(χ=0, 0,01.0.03, 0.05, 0.08, 0.1) were fabricated by an arc melting furnace under a high purity argon atmosphere. The microstructure, magnetostrictive properties and mechanical performance were studied systematically. The results show that the (Tb,Dy)Cu phase forms in these alloys upon the addition of Cu. Correspondingly, their toughness improves, attributed to the formation of a (Tb,Dy)Cu phase. Compared to the Cu-free alloy, the fracture toughness (Kic) increases 2-3 times with increasing Cu content. However, the magnetostriction performance of these alloys declines with Cu addition, due to the low-magnetic performance of the (Tb,Dy)Cu phase at room temperature. Compared with other alloys, the alloy with the addition of 1at%Cu shows the best compromise between the saturation magnetostriction and fracture toughness.     

Effects of trace ytterbium addition on microstructure,mechanical and thermal properties of hypoeutectic Al–5Ni alloy

Over the past decade, the cast aluminum alloys with excellent mechanical and conductivity properties have emerged as potential materials for thermal management. However, the traditional Al–Si based alloys are difficult to make significant breakthrough in conductivity performance. The hypoeutectic Al–5Ni alloy also possesses sound castability and is expected to be applied in thermal management applications. In this study, the effects of ytterbium (Yb element) at 0–0.5 wt% on the microstructures as well as the electrical/thermal conductivity and mechanical properties of the Al–5Ni alloy were systematically investigated. The experimental results indicate that the addition of Yb at a relatively low amount not only reduces the secondary dendrite arm spacing of the α-Al grains, but also modifies the morphology and distribution of eutectic boundary phase. Moreover, it is found that the dosage of Yb at 0.3 wt% in the Al–5Ni alloy can simultaneously improve the yield strength, ultimate tensile strength and electrical/thermal conductivity. The strengthening and toughening of the Al–5Ni alloy are mainly attributed to the decrease of secondary dendrite arm spacing and the improvement of eutectic phases. The transmission electron microscopy/selected area electron diffraction (TEM/SAED) analysis indicates that the ytterbium in Al–5Ni alloy will form Al₃Yb phase, which mainly agglomerates in the Al₃Ni phase region. This phase is helpful to decrease the solubility of impurity elements (e.g., Fe and Si) in the α-Al matrix, which is beneficial to electrical/thermal conductivity. The value of this study lays foundation for manufacturing Al–Ni alloys with high thermal conductivity and acceptable mechanical properties.     

Microstructure and mechanical properties of Mg-7Zn-3Al alloy with Nd and Y additions

The effects of combined addition of 0.6 wt.% Nd and 0.4 wt.% Y on the microstructure and mechanical properties of Mg-7Zn-3Al alloy were investigated.The results indicated that the Nd and Y addition led to obvious dendrite coarsening.However,it could modify the morphology and distribution of-Mg 32(Al,Zn) 49 intermetallics.Moreover,Al 2 REZn 2 phase could be introduced into the alloy with the Nd and Y addition.With the effective second-phase strengthening,the ultimate tensile strength and elongation in as-cast state can be improved by the Nd and Y addition.After ageing treatment,the alloy with the Nd and Y addition exhibited better precipitation strengthening effects by forming finer MgZn 2 and Mg 32(Al,Zn) 49 precipitates into the-Mg matrix.As a result,the yield and ultimate strength of Mg-7Zn3Al-0.6Nd-0.4Y alloy could be increased to 182 and 300 MPa by peak-ageing treatment.     

Relationship between crystal growth mode, preferred orientation and magnetostriction of (Tb0.3Dy0.7)Fe1.95 alloys

The relationship between crystal growth mode, preferred orientation and magnetostrictive properties of (Tb0.3Dy0.7)Fe1.95 alloys was investigated at different directional solidification rates. The results showed that preferred orientation had a strong influence on the characteristics of (Tb0.3Dy0.7)Fe1.95 alloys. At lower solidification rates, the sample with <110> preferred orientation showed larger low-field magnetostriction and apparent compressive stress effect. The excessive solidification rate resulted in failure of preferred orientation and a poor magnetostrictive performance. With an increase in solidification rates, the crystal growth modes changed gradually from cellular and primary dendrite morphology to developed dendritic morphology. In addition, domain configurations were observed using magnetic force microscopy, and the change of magnetostrictive properties was interpreted in terms of revealing the domain configurations.     

Sm对AZ61合金力学性能的影响

采用XRD、OM和SEM手段研究了Sm(0～2.0%,质量分数,下同)对AZ61合金显微组织和力学性能的影响。结果表明,Sm优先与A1形成高熔点Al2Sm弥散相,细化合金显微组织,提高时效态合金室温抗拉强度和屈服强度。在研究范围内,加入1.5%Sm的合金力学性能最优。Sm可以通过细晶强化、Ramakrishnan强化和Gypen固溶强化机制对AZ61合金强度产生影响。     

Glass-Fibre-Reinforced Aluminium Alloys Formed by Hot Extrusion: Part I: Preparation and Properties

Abstract

An investigation was conducted to study the variation of properties of a WC–TiC–TaC–NbC–Co alloy with carbon content. Carbon content was varied by adding tungsten and/or carbon black to the powder mixture. Lattice parameter measurements by X-ray diffraction showed the maximum solubility of tungsten in cobalt to be ～10%. Besides α-cobalt, the presence of ε-cobalt was also observed. There is little change in cobalt lattice parameters, hardness, and coercive force outside the region where three phases are present. Although toughness reaches a maximum above the stoichiometric carbon content, optimum machining performance is obtained at a rather lower carbon content. With 5–8% tungsten in solution in the binder, the binder strength is improved, which explains the satisfactory machining results. PM/0193     

2,3,5-吡啶三酸与重稀土配合物的合成、表征及光致发光性质

采用水做溶剂,用2,3,5-吡啶三酸做配体和重稀土铽、镝、铒、镱、镥、钇六种稀土元素的氯化物在常温下反应合成了六种重稀土的配合物。通过EDTA络合滴定分析,确定了六种配合物中稀土离子含量;并对配合物进行了熔点测定、红外光谱测试,并测试了铽和镝配合物的光致发光性质,结果表明,铽和镝配合物在紫外光的激发下具有良好的发光性质。     

不同稀土掺杂聚苯乙烯力学性能研究

选择了几种功能不同的Pr，Eu，Gd，Th，Dy，Ho和Er的三异丙氧基化合物与苯乙烯本体聚合获得稀土掺杂聚苯乙烯，采用ESEM，DMTA，冲击强度测试研究了不同稀土对聚合物力学性能的影响，结果表明不同稀土引入聚苯乙烯中均能使韧性得以提高，它们的力学性能与稀土的原子序数、原子半径大小有关。