大块非晶合金制备技术进展

介绍了大块非晶合金的制备方法,并从成分结构条件等方面阐述了大块非晶合金的形成机制,描述了大块非晶合金玻璃形成能力的各种判据。对一些方法、特点进行了讨论,并对它们进行了初步对比。     

大块非晶合金力学性能研究进展

对大块非晶合金力学性能研究领域的最新进展进行了综述,介绍了新型不同系列大块非晶合金的结构和成分特点,特别是与传统晶态合金相比,相同成分的大块非晶合金具有优异的力学性能,其弹性比拉伸断裂强压缩断裂强度、弯曲断裂强度、摆锤冲击断裂能、断裂韧性和弯曲疲劳强度均较高,同时,对此类合金的应用前景进行了简要评述。     

Fe-Nd-Al系块状非晶合金的形成

采用铜模铸造法研究了Fe-Nd-Al系合金块状非晶的成分范围、合金元素对非晶形成能力的影响、Fe-Nd-Al系块状非晶的形成能力与约化晶化温度的关系.研究结果表明,Fe-Nd-Al系合金的非晶形成能力很强,成分在Fe50~42.5NdyAl7.5~17.5范围内能制得直径达2~3 mm的非晶棒材;添加B,Ni,Co,Y,Zr,Si,Ti替代部分Al可以提高合金的GFA;合金的Tx/Tm值愈高,非晶形成能力越强.     

ZrCuAlMo大块非晶的制备及热稳定性研究

通过铜模吸铸法制备（Zr47Cu44Al9）100-xMox（x=0,1,2,3）大块非晶合金.利用X射线衍射、差热分析等,研究分析添加Mo对Zr47Cu44Al9合金非晶形成能力及热稳定性的影响.结果表明,Mo的添加量为2%时,合金具有最大的非晶形成能力,纯非晶试样的临界尺寸从4mm增大到6mm以上,8mm的样品只有微弱的衍射峰.Mo提高非晶形成能力的原因主要是抑制引起异质形核的CuZr相的析出与长大.利用Kissinger方法计算得到的其玻璃转变激活能Eg为278.57kJmol-1、晶化激活能Ex为392.46kJmol-1、晶化峰值的激活能Ep为376.97kJmol-1.与原合金相比,晶化激活能与晶化峰值激活能的数据都增大,说明Mo的添加不仅提高了原合金的非晶形成能力,同时也增强了合金的热稳定性.     

大块非晶合金的研究进展

大块非晶合金由于其在科学技术上的重要意义而广受关注.从大块非晶合金的发展历史出发,综述大块非晶合金形成的各种判据、特性、微观结构分析及其应用,并对今后发展的方向进行展望.     

Zr60Ni21Al19块体非晶合金的耐电化学腐蚀和抗氧化性能

该文研究了块体非晶态Zr60Ni21Al19合金的耐电化学腐蚀和抗氧化性能．非晶态Zr60Ni21Al19三元合金比与其同成分的晶态合金和0Cr18Ni9Ti不锈钢表现出了更正的电极电位,而且其在2mol／L HCl溶液中的腐蚀失重小于与其同成分的晶态合金和0Cr18Ni9Ti不锈钢,甚至小于五元的非晶态ZrTiCuNiBe合金．抗氧化性方面,虽然非晶态Zr60Ni21Al19三元合金好于与之同成分的晶态合金,但两者均表现出了良好的抗氧化性．     

含孔洞大块非晶合金变形行为的数值研究

建立能够描述静水压力影响和塑性体积膨胀的率相关的大块非晶合金本构模型.通过编写ABAQUS材料用户子程序VUMAT,对含不同形态孔洞的Zr基大块非晶合金的变形行为进行有限元分析,并对其细观变化规律进行研究.     

Cu60Zr33Ti7非晶合金的非等温晶化动力学行为

采用铜模吸铸法制备Cu60Zr33Ti7大块非晶合金(BMGs),用X射线衍射仪(XRD)、透射电子显微镜(TEM)确定其非晶态结构,并利用同步示差扫描量热仪(DSC)对其晶化动力学进行研究.结果显示:该BMGs第一晶化峰晶化产物为Cu10Zr7,其晶化过程有显著的动力学效应.由Kissinger法和Ozawa法得到的全局晶化激活能分别为116.27、122.9kJ·mol-1,该大块非晶合金具有很好的热稳定性.     

非晶合金发展及制备

概述了大块非晶态材料的发展历史,并从成分结构条件、热力学条件、动力学条件等方面阐述了大块非晶合金的形成机制。介绍了大块非晶合金的制备方法,描述了大块非晶合金玻璃形成能力的各种判据。     

大块非晶合金热塑性成形的研究进展

介绍了大块非晶合金的特性及其应用,对大块非晶合金的热塑性成形原理、技术及其研究进展进行了详细的综述,并展望了大块非晶合金热塑性成形的发展趋势。     

Magnetocaloric effect in Gd<Subscript>5</Subscript>Si<Subscript>1.85</Subscript>Ge<Subscript>2.15</Subscript> prepared by Gd metal with lower purity

Recently, Pecharsky et al. have discovered that Gd5(SixGe1-x)4 (0 < x <0.5) has a significantly large mag-netocaloric effect (MCE), which is 50% to 200% larger than any known materials[1—4]. This behavior is called as 慻iant magnetocaloric effect? The giant MCE is caused by simultaneous magnetic and crystallographic transition in these alloys. The first order magnetic ordering tem-perature of Gd5(SixGe1-x)4 can be tuned from 20 to 280 K by changing the ratio of Si︰Ge[2]. The temperat…     

低磁化率锆合金的研究进展

金属植入物在磁共振成像（magnetic resonance imaging,MRI）诊断中常产生较大的伪影,严重降低MRI图像的质量,进而影响病理诊断分析。降低金属植入物的磁化率是降低MRI伪影的有效途径。医用锆合金以其优良的生物相容性,优越的综合力学性能和较低的磁化率成为近年来的研究热点。回顾了锆合金的发展历史,分析了相组成和合金元素对锆合金磁化率的影响,详细介绍了Zr-Nb合金、Zr-Mo合金、Zr-Ru合金等低磁化率锆合金的研究现状,展望了锆合金作为医疗器械候选材料的发展前景。     

Study on precipitation and transition mechanisms from the magnetic properties of silicon steel during annealing

Precipitates play an important role in determining the mechanical and magnetic properties of silicon steel. This paper aims to investigate the growth kinetics of precipitates in commercial silicon steel by analyzing its magnetic properties during isothermal annealing at 200℃. The growth of precipitates was studied by optical microscopy, scanning electron microscopy, transmission electron microscopy, and magnetic measurements. In combination with the coercive field and initial susceptibility, this technique offers the advantage of being non-destructive and providing quantitative information about the number, mean radius of precipitates, and fraction of transformation. An observed decrease in the number of precipitated particles indicates that the transformation starts from particles of appreciable initial size.     

Effects of Yb^3＋ codoping on visible and near infrared emissions of Er^3＋-Yb^3＋ codoped Al2O3 powders by the sol-gel method

The 0.1 mol% Er^3＋ and 0-2 mol% Yb^3＋ codoped Al2O3 powders were prepared by the sol-gel method, and the phase structure, including only two crystalline types of doped Al2O3 phase, γ-（Al,Er, Yb）2O3 and θ-（Al,Er, Yb）2O3, was detected at the sintering temperature of 1000℃. The visible and near infrared emissions properties depended strongly on the Yb^3＋ codoping, and the corresponding maximal peak intensities centered at about 523, 545, 660 and 1533 nm were obtained respectively for the 0.1 mol% Er^3＋ and 0.5 mol% Yb^3＋ codoped Al2O3 powders, which were composed of θ-（Al,Er,Yb）2O3 and a small amount of γ-（Al,Er, Yb）2O3 phases. The two-photon absorption process was responsible for the visible up-conversion emissions, and the one-photon absorption process was involved in the near infrared emissions of the Er^3＋-yb^3＋ codoped Al2O3 powders.     

Cr掺杂闪锌矿AlP半导体的电子结构及磁性研究

在共轭梯度近似（GGA）下，采用基于密度泛函理论的第一性原理平面波赝势方法，对Cr掺杂闪锌矿AlP半导体的基态电子结构和磁性进行研究．结果发现，Al0.5Cr0.5P体系具有显著的半金属特征，晶胞总磁矩为3μB／Cr．这对在半导体工业中实现自旋载流子注入具有一定的理论价值。     

SYNTHESIS AND CHARACTERIZATION OF MONOVALENT AND MIXED-VALENCE COMPLEXES OF COPPER WITH 2-THIOURACIL

Five polynuclear monovalent and mixed-valence complexes of copper with 2-thiouracil were synthesized. They were characterized by the molar conductivity, electromc spectra, infrared spectroscopy, thermogravimetric and magnetic susceptibility measurements. Their coordination properties and tentative structures were discussed.     

Synthesis and Magnetic Properties of Spin-Liquid Tb2Ti2O7

Polycrystalline samples of a novel spin-liquid compound Tb2Ti2O7 were prepared by a standard solid-state reaction. X-ray diffraction at room temperature confirms that the synthesized compound of Tb2Ti2O7 is single phase with cubic unit cell constant a0 of 1.015 44 nm. Magnetic susceptibility measurements in the temperature range between 100 and 300 K give an effective moment of 9.44 μB and Curie-Weiss temperature of 12.68 K, respectively, indicating the dominance of antiferromagnetic interactions. However, below 50 K, the magnetic behavior of Tb2Ti2O7 deviates from Curie-Weiss law, whose origin remains suspicion.     

First-principles calculations of the β′-Mg<Subscript>7</Subscript>Gd precipitate in Mg-Gd binary alloys

The metastable β’ phase is often the most effective hardening precipitate in Mg-Gd based alloys.In this paper,the structural,elastic and electronic properties of the recently identified β’-Mg7Gd precipitate in Mg-Gd binary alloys were investigated using first-principles calculations based on density functional theory.The lattice mismatches between the coherent β’-Mg7Gd precipitate and α-Mg matrix are discussed and used to rationalize the experimentally observed morphology of the precipitate.The mechanical properties were investigated through analysis of the single-crystal elastic constants and the polycrystalline elastic moduli.It is found that β’-Mg7Gd is brittle in nature.Strong covalent bonding in β’-Mg7Gd,as inferred from its electronic structure,further explains its mechanical properties.Our theoretical results show good agreement with experimental measurements.     

Al^3＋ -induced vesicle formation

Aluminium laurate [Al(OOCC11H23)3] was synthesized as a surfactant, which can dissolve in micellar solution of a zwitterionic surfactant, tetradecycldimethylamine oxide (C14DMAO). The phase behavior of the mixtures of Al(OOCC11H23)3 and C14DMAO in water was studied and birefringent Lα-phase was observed. The birefringent Lα-phase consists of vesicles that were demonstrated by Polarizer and Transmission Electron Microscope (TEM) micrographs. Al3 -coordinated vesicles could be used as templating-precursor, providing a vesicle-route for preparation of inorganic nanoscale particles.     

饱和多相流体孔隙介质内部磁场梯度的探测

饱和流体孔隙介质中存在的内部磁场梯度会对孔隙介质的核磁共振产生显著影响,提出了一种基于（T2int,D）二维核磁共振方法计算饱和多相流体孔隙介质内部磁场梯度的方法,可以计算饱和水以及油水多相流体的孔隙介质中内部磁场梯度．数值模拟与实验测量表明,该方法计算的饱和流体孔隙介质内部磁场梯度是有效的．