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。     

应力对退火态Sm-Fe-BGMF磁学性能的影响

利用离子束溅射(IBSD)法,在盖玻片衬底上制备Sm-Fe-B超磁致伸缩薄膜(GMF)样品;并在退火过程中对其施加预应力,研究应力对退火态Sm-Fe-B薄膜磁畴结构、软磁性能及磁致伸缩性能的影响并分析其差异产生的原因。结果表明:退火过程中施加预应力能使薄膜磁畴结构发生显著变化,通过改善退火态薄膜的微结构与应力状态,能有效提高薄膜的软磁性能与磁致伸缩性能;与自由退火态样品比较,应力退火态样品具有较明显的垂直各向异性,虽然在低场磁敏性方面略有降低,但是在饱和磁致伸缩性能方面有较大提高。     

Fe-Ga磁致伸缩合金相结构及其制备工艺研究进展

与已商业化的Terfenol-D磁致伸缩材料相比,新型磁致伸缩Fe-Ga合金以其高强度、良好韧性、低磁场高磁致伸缩和低成本等优势成为目前凝聚态物理和材料科学领域的研究热点。Fe-Ga合金的磁致伸缩性能取决于合金的微结构,特别是该类合金的相结构。而Fe-Ga合金的微结构又密切相关于合金的制备工艺。从Fe-Ga二元合金的基本相结构出发,在详细分析平衡态和亚稳态Fe-Ga二元合金相图的基础上,重点综述了Fe-Ga合金的相结构对其磁致伸缩性能的影响;之后,详细综述了各种制备工艺下Fe-Ga合金的相结构和磁致伸缩性能;最后展望了该类合金未来发展方向。     

《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.     

速凝成晶-粘结法制备稀土磁致伸缩材料TbDyFe的研究

采用速凝成晶技术,制备了具有<112>和<110>择优取向的Tb0.27Dy0.73Fe1.95速凝片.研究发现,速凝片的择优取向和显微组织与冷却速度密切相关.随着冷却速度的增加,其择优取向从<112>向<110>变化,显微组织由枝状晶向胞枝晶转变.研究了由速凝片制备的稀土粘结磁致伸缩样品的性能.结果表明,当粉末粒度≤(100～150)μm时材料性能较好,具有<112择优取向的样品性能高于<110>择优取向的样品,磁场取向成型有利于材料性能的改善.获得了性能良好的粘结磁致伸缩材料,在238.8 kA·m-1时磁致伸缩系数达到740×10-6.     

粘结超磁致伸缩Tb-Dy-Fe合金磁致伸缩性能的研究

采用粘结方法制备了Tb1-xDyxFe2棒状合金样品，经筛选确定了粘结材料的制备工艺，测试了粘结棒状合金样品的静态、动态磁致伸缩系数和磁机械耦合系数k33。结果表明，所制备的粘结棒状样品具有较高的磁致伸缩性能，且动态磁致伸缩参数k33和磁机械耦合系数k33高于国外所报道的结果。     

第四届中国国际稀土学术会议将在北京召开

由中国稀土学会(ＣＳＲＥ)主办的第四届中国国际稀土学术会议将于2001年6月15～20日在中国北京召开。会议内容主要包括以下3个部分:Ａ:稀土新材料和应用:磁性材料和磁学,超磁致伸缩和磁阻材料,磁致冷,磁光材料;高Ｔｃ超导体;贮氢材料和电池;发光、荧光和激光材料。Ｂ:稀土化学:配位化学和金属有机化学;生物无机化学;固态化学;稀土在农、医等方面的应用;稀土催化材料;电子结构和光谱;分析化学;溶液化学;熔盐化学;物理化学。Ｃ:稀土资源和冶金:稀土分离技术,数字模型,萃取机制,加工工艺,在线分析和自动控制;湿法冶金和设备,金属与合金的制备,…     

粉末冶金法制备稀土超磁致伸缩材料的研究

介绍了一种粉末冶金制备稀土磁致伸缩材料的方法,该方法包括铸造Tb0.30Dy0.70Fe1.80合金锭、制粉、磁场取向、压制成型和烧结工序。实验结果表明:粒度小于0.147 mm的Tb0.30Dy0.70Fe1.80合金粉末,经磁场取向后压制成型,在1200℃烧结2 h,并在950℃热处理24 h,当磁场强度为240 kA.m-1,预应力为8 MPa时,材料的磁致伸缩系数达到1.613×10-3。     

硝酸铽与1,1,1'''',1''''-四(吡啶-2-羧酸酯基)联三甲基丙烷配合物的合成、表征及荧光性质

稀土离子具有独特的电子结构和成键特征,配位数高且多变,因而稀土配合物能表现出独特的光、电、磁性质。目前,设计和合成含有稀土离子的功能配合物作为发光分子器件和荧光探针是配位化学和超分子化学等研究领域的热点课题[1￣6]。研究表明,稀土配合物的发光性能和稳定性可通过改变其配体的组成和结构加以调控。因此,设计、合成具有新颖结构、良好配位能力及高效能量吸收和传递性能的有机配体是研究和开发新型稀土配合物发光材料的关键课题之一。多足配体在与金属离子配位时,能够表现出特有的选择性配位能力、类球形配位空穴和新颖的配位结构…     

Zn_xCoFe_2O_4的制备及磁性能和磁致伸缩性能的研究

本实验采用溶胶—凝胶自蔓延的方法,将富含Co元素的废旧锂电池加工成一系列的含锌量不同的钴铁氧体样品,并对不同锌含量样品的形貌、结构、磁性能和磁致伸缩性能进行研究。实验结果表明:含锌的钴铁氧体是尖晶石结构的晶体,与Co Fe_2O_4相比,微观结构和形貌发生了变化,因此,性质发生了明显的变化。随着锌含量的增加,样品的饱和磁化强度先增加后减小;最大磁致伸缩系数整体递减;磁致伸缩应变导数的最大值整体递增,该值对应的磁场强度逐渐降低。研究表明:Zn~(2+)含量为0.4时,样品的最大磁致伸缩系数,最大应变导数及其对应的场强分别是-134.8 ppm,-2.12×10~(-9)A~(-1)m和20.0KA·m~(-1),即应变导数在较低的磁场强度下取得最大值,使用该样品制备而成的器件在非接触式传感器和执行器方面的应用中可能更具优势。     

The effects of a eutectic modifier on microstructure and surface corrosion behavior of Al-Si hypoeutectic alloys

Hypoeutectic aluminum–silicon alloys can have significant improvements in mechanical properties by inducing structural modification in the normally occurring eutectic. The eutectic modification may affect not only the mechanical properties but also the corrosion resistance of such alloys. It is well known that structural parameters such as grain size and interdendritic spacing can significantly affect corrosion resistance of alloys. However, to date, few researches have been performed to experimentally evaluate the effects of an effective modification of eutectic morphology on surface corrosion behavior of Al–Si alloys. In the present study, modified and unmodified samples of an Al 9 wt.% Si alloy were solidified under similar solidification conditions, and after metallographic procedures, the corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and the Tafel extrapolation method carried out in a 0.5 M NaCl test solution at 25 °C. The impedance parameters and corrosion rate were obtained from an equivalent circuit analysis. It was found that the Al-9 wt.% Si alloy casting in the modified condition tends to have its corrosion resistance decreased when compared to the unmodified alloy.     

Characterization and corrosion resistance of pure Mg modified by micro‐arc oxidation using phosphate electrolyte with/without NaOH

Magnesium and its alloys have been suggested as potential absorbable implant materials due to their excellent biodegradability and biocompatibility. Current researchers focus on reducing the rapid corrosion rate of Mg and its alloys by alloying and surface modification. To improve the corrosion resistance, pure Mg is modified by micro‐arc oxidation (MAO) in phosphate electrolyte containing sodium hydroxide and its properties are compared with those formed using only phosphate or sodium hydroxide as electrolytes. A uniform and stable coating layer is formed on Mg after MAO treatment in phosphate electrolyte containing sodium hydroxide. The corrosion resistance of MAO‐coated Mg is evaluated by potentiodynamic polarization study and immersion test. The results reveal that MAO coating enables a good improvement in corrosion resistance, and among them, coatings treated using phosphate electrolyte containing sodium hydroxide offer the best performance. Copyright © 2013 John Wiley & Sons, Ltd.     

Photocatalytic,phosphorus-doped,anatase oxide layers applicable to titanium implant alloys

Titanium alloys provide excellent corrosion resistance and favorable mechanical properties well suited for a variety of biomaterial applications. The native oxide surface on titanium alloys has been shown to be less than ideal and surface modification is often needed. Previously, an optimized anodization process was shown to form a porous phosphorus-enhanced anatase oxide layer on commercially pure Ti grade 4. The anodized layer was shown to improve osseointegration and to reduce bacteria attachment when photocatalytically activated with UVA preillumination. The primary objective of the present study was to create a similar phosphorus-enhanced anatase oxide layer on series of titanium alloys including commercially pure Ti grade 4, Ti-6Al-7Nb, Ti-6Al-4V ELI, alpha + beta Ti-15Mo, beta Ti-15Mo, and Ti-35Nb-7Zr-5Ta. Phosphorus-enhanced anatase oxide layers were formed on each titanium substrate. Anatase formation was shown to generally increase with oxide thickness, except on substrate alloys containing niobium. Phosphorus uptake was shown to be dependent on the titanium alloy chemistry or microstructure. Anodized layers formed on beta-structured titanium alloys revealed the lowest phosphorus uptake and the most nanosized surface porosity. A methylene blue degradation assay showed anodized layers on commercially pure Ti and both Ti-15Mo alloys to exhibit the highest levels of photocatalytic activity. Given the range of mechanical properties available with the commercially pure Ti and Ti-15Mo alloys, the results of this study indicate the benefits of phosphorus-enhanced anatase oxide coatings may be applicable to a wide variety of biomaterial applications.     

医用钛表面TiO_2纳米管/HA复合膜层于Tyrode’s生理溶液中电化学腐蚀行为

钛及其合金具有良好的力学性能和生物相容性,被广泛地用作医用人工植入体.然而,钛植入体在人体内的生理环境中必然发生腐蚀,金属离子的溶出和积累可产生毒副作用.本文应用电化学方法对医用钛金属作表面改性,提高其生物活性,应用Tafel极化曲线和电化学阻抗(EIS)研究其耐蚀性能及腐蚀电化学行为.结果表明,在钛基TiO2纳米管阵列膜层上沉积构筑HA涂层之后,由于表面阻挡层的强化,TiO2涂层在Tyrode’s生理溶液中的耐蚀性有所提高.     

Ionic liquids: Electrochemical investigation on corrosion activity of ethyl-dimethyl-propylammonium bis(trifluoromethylsulfonyl)imide at high temperature

In the present work we report on our investigation on the corrosion properties of the ethyl-dimethyl-propylammonium bis(trifluoromethylsulphonyl)imide at temperatures up to 473 K. The tests were performed both for commercially pure iron alloys and for pure copper. The electrochemical measurements showed that the metals corrosion rates can be dramatically reduced by purging the ionic liquid with inert gases to remove the dissolved oxygen.     

添加铈对低锑铅合金的微观结构及电化学性能的影响

采用金相显微镜和电镜扫描观察Pb-Sb-As-Sn-S-Ce合金的微观组织形态,用显微硬度仪测试合金的硬度,研究了铈对含砷锡硫的铅锑合金微观结构及合金硬度的影响;应用循环伏安法、交流阻抗法和阴极极化曲线来分析铈的添加对Pb-Sb-As-Sn-S合金的电化学性能的影响。结果表明：铈能细化铅锑合金晶粒,薄化晶界,减少晶体缺陷,能提高铅锑合金的硬度,降低整体腐蚀速度和腐蚀的危害性,提高低锑铅合金的耐腐蚀性能,增大电池的循环寿命。     

Electrochemical deposition and corrosion stability of Zn–Co alloys

Electrochemically deposited Zn–Co alloys under various deposition conditions were investigated using anodic linear sweep voltammetry for phase structure determination, scanning electron microscopy for surface morphology analysis, atomic absorption spectroscopy for determination of chemical composition, and polarization measurements and open circuit potential measurements for determination of corrosion properties. The influence of deposition current density, temperature, and composition of deposition solution on the phase structure and corrosion properties of Zn–Co alloys was studied. It was shown that the ratio of cobalt to zinc ions in the plating bath strongly affects the chemical content and phase structure, as well as corrosion stability, of Zn–Co alloys. Zn–Co alloys deposited from plating baths with the lowest and the highest ratios of cobalt and zinc ions exhibited the lowest corrosion rate.     

功能化离子液体修饰多壁碳纳米管固定化Candida antarctic lipase B

将带不同阴离子（Br^-、BF₄^-、PF₆^-、H₂PO₄^-）的咪唑离子液体修饰改性的多壁碳纳米管（MWNTs）作为一种全新的载体通过物理吸附法固定化褶皱假丝酵母脂肪酶B（CALB）,对其酶学性能进行测试。并通过透射电镜、拉曼光谱、热重分析、X射线光电子能谱对修饰前后的MWNTs进行表征,研究材料表面修饰对酶学性能的影响。研究结果表明,经过离子液体表面修饰后的MWNTs固定化CALB具有更高的比活力,耐受性（高温、高pH值）、热稳定性和重复使用性也得到进一步增强;离子液体中不同的阴离子对修饰MWNTs固定化酶的酶学性能有显著影响,其中以PF₆^-为阴离子的固定化酶比活力最高,比未修饰的MWNTs提高了5倍。固定化酶的动力学参数分析表明离子液体的引入增强了酶与底物之间的亲和力,从而增强了酶的活性。     

Corrosion-resistant composite coatings on biodegradable magnesium alloys: In vitro studies

A composite coating was formed on MA8, MA14, and MA12 magnesium alloys by plasma electrolytic oxidation with subsequent immersion of samples into a superdispersed polytetrafluoroethylene suspension. In vitro volumetry determined that using this coating significantly reduces the magnesium alloy dissolution rate. It was shown that superdispersed polytetrafluoroethylene seals pores of the coating, thus reducing the corrosion rate in an artificial medium that mimics human blood by ionic composition. However, the surface of the calcium phosphate coating (Ca: P = 1.61) containing hydroxyapatite remains open for contact with the environment. The obtained data suggested that the proposed method for surface treatment of MA8, MA14, and MA12 alloys is promising for producing biodegradable protective coatings on magnesium medical implants.     

Al electroplating on the AZ121 Mg alloy in an EMIC–AlCl3 ionic liquid containing ethylene glycol

To improve the corrosion resistance of Mg alloys, an Al layer was electrodeposited on the Mg surface from an ionic liquid of 1-ethyl-3-methylimidazolium chloride (EMIC) and aluminum chloride (AlCl₃) at 283?K. A smooth surfaced Al electrodeposit can be electroplated in the AlCl₃–EMIC ionic liquid by pulse electrolysis at 6.7?Hz and a duty ratio of 0.67. A denser and flatter Al layer was successfully electroplated on AZ121 substrate at the lower temperature of 283?K in an AlCl₃–EMIC ionic liquid with 0.1?M ethylene glycol added.