时效转变与Ti/(Ti,Zr)2Si复合材料的制备

通过真空自耗电极炉熔炼得到硅锆比为1，2的Ti—Zr—Si合金材料，对合金材料进行了1200℃，3．5h的固溶处理和850℃不同时间的时效处理，通过时效析出反应制备Ti／(Ti，Zr）2Si复合材料。利用光学显微镜、扫描电镜、X射线衍射、EDX分析了Ti—Zr—Si合金的铸造、固溶和不同时效阶段的显微组织及其相组成。分析结果表明，硅锆比为1／2(重量百分比)的Ti—Zr—Si合金，铸造组织为块状β—Ti、晶界由块状β—Ti和条状的5—3型硅化物组成；Ti—Zr—Si合金经过850℃，480min的时效处理，5—3型硅化物转变为2—1型硅化物；尺寸细小、分布均匀的2—1型硅化物使制备高性能的Ti／(Ti，Zr)2Si复合材料成为可能。     

介稳定β钛合金TB2中的两个新的温度参数

在“Ti—5Mo-5V—8Cr-3Al合金研制总结”中,我们曾介绍了该合金的相变温度及再结晶温度。相变温度和再结晶温度做为合金的基本温度参数,其重要性是人所共知的。随后进一步研究发现TB2合金中还存在着两个新的温度参数——临界淬火温度和转折温度,这两个温度参数对介稳定β钛合金TB2的组织和性能有较重要的影响。相变温度、再结晶温度、临界淬火温度和转折温度构成TB2合金的四个温度参数。本文     

SHS法制备钛基复合材料用的TiC颗粒

研究了由Ti，C，Al元素粉末通过自蔓延高温合成(SHS)工艺制取TiC颗粒过程中体系物相组成的变化情况，以及合成产物的状态。采用燃烧波淬熄法制备了样品，用X射线衍射(XRD)和扫描电子显微(SEM)技术分析、检测了所得样品的相组成和微结构。结果表明，在Ti—C—Al系的燃烧合成反应中，分别产生Ti—Al，Ti—C和Al—C间的多个反应，生成多种金属间化合物相，但最终产物以TiC和纯Al相为主。反应产物的形态为纯Al相分隔的符合化学计量比的等轴TiC颗粒多孔堆积体，颗粒大小均匀，尺寸多在2μm一8μm之间。     

钇对Ti-43Al-9V合金组织性能的影响

采用OM，XRD，SEM和TEM等测试方法，分析了稀土元素(Y)对Ti—43Al—9V合金显微组织以及力学形能的影响。实验结果表明，Ti—43Al—9V—0．3Y合金由γ相、α2相、B2相和YAl2相组成；添加稀土可以细化Ti—43Al—9V合金的晶粒尺寸，并促进细小的α2／γ层片形成以及细化粗大的α2／γ／B2层片。对TiAl合金力学性能测试表明，适量添加稀土Y(0．3％，原子分数)可明显改善合金的室温强度和塑性，但过量添加将会造成材料性能降低；断口分析表明过量添加稀土导致沿晶断裂比例增加将损害TiAl合金的性能。     

大热流通量条件下原位合成Fe-TiC复合材料的研究

首次应用Gleeble热模拟机研究Fe—Ti—C体系在大热流通量条件下原位合成Fe—TiC复合材料。通过压坯在加热升温过程所反映出的特点，结合热力学计算，以及对产物的x射线衍射分析(XRD)、扫描电镜(SEM)以及能谱分析(EDS)等的研究分析，结果表明：在大热流通量下，可以大幅度地降低合成反应起始温度，且反应完全。在实验研究条件下，Fe—Ti—C体系可在394℃的低温条件下发生合成反应。合成的产物除了分布在铁基体中的小颗粒TiC外，还有少量的Fe2Ti。此研究结果为低温合成Fe—TiC复合材料提供了一条新途径。     

时效强化Fe-Ni-Ti-Al因瓦合金的力学与膨胀特性

研究了Fe—Ni—Ti—Al因瓦合金化学成分、热处理工艺、冷加工工艺对合金力学和膨胀特性的影响。实验结果表明，Ti,Al的加入使合金膨胀系数增大，同时随着Ti,Al的加入，应适当增加Ni含量，以保证合金具有较低的膨胀系数；冷加工降低Fe—Ni—Ti—Al合金的膨胀系数，时效热处理则增大合金的膨胀系数。含Ti2．5％（wt），AI0．6％（wt）的Fe—Ni—Ti—A1因瓦合金经时效热处理和变形强化，抗拉强度可达1500MPa。     

(Ti,M)(C,N)基金属陶瓷显微组织与力学性能的研究进展

(Ti,M)(C,N)基金属陶瓷是重要的刀具及涂层材料。综述了国内外(Ti,M)(C,N)基金属陶瓷显微组织和力学性能的研究进展,对(Ti,M)(C,N)基金属陶瓷的黑芯—白内环—灰外环和白芯—灰环显微组织结构特征进行了阐述。系统综述了TiC/TiN含量、Co、Ni粘结相含量、Mo、WC、VC、Cr_3C_2、TaC、NbC添加剂成分对(Ti,M)(C,N)基金属陶瓷显微组织和力学性能的影响,并指出接下来的深入研究方向。结果表明:(Ti,M)(C,N)基金属陶瓷显微组织中芯—环相结构的形成受到原始粉体粒度的影响,当碳化物原始粉体为微米级时形成黑芯—白内环—灰外环结构;当碳化物原始粉体尺寸为亚微米及纳米时形成白芯—灰环结构。金属和陶瓷性能优势的结合依赖于显微组织的调控。多组元添加剂制备的复式(Ti,M)(C,N)基金属陶瓷显微组织中环相和芯相界面能的匹配、硬质相晶粒尺寸分布及取向分布等机理研究有待进一步深入。     

依据~(31)P和~(45)Sc核磁共振资料用ТБФ和ТВЭКС-ТБФ从硫酸溶液中萃取钪

本文对用ТВФ和ТВЭКС-ТВФ从硫酸溶液中萃取钪进行了研究。采用~(31)P和~(45)Sc核磁共振方法确定,在萃合物中没有P=O→Sc配位键存在。研究表明,在6mol/LH_2SO_4中,钪的萃取是按照在有机相中生成[Sc(SO_4)_3]~(3-)络合物的水合溶剂化机制进行的。Sc在ТВЭКС—TBФ中的分配系数比用液体TBФ时有所提高,这可以用TBФКС聚合物中的萃取剂的状态特性进行解释。     

Ni-Ti形状记忆合金薄膜的研究和应用

Ni—Ti形状记忆合金(SMA)薄膜由于其尺寸小输出功大，是一种有诱人前景的微机械材料。本文主要介绍了Ni—Ti形状记忆合金薄膜的马氏体相变、时效稳定性、R相变、退火对相变温度的影响、力学性能以及最近的应用。     

Ti-Al系电子结构及Mn掺杂对TiAl_3室温脆性的影响

以Ti-Al的3个化合物相(Ti3Al、TiAl和TiAl3)及Ti3Al8Mn为对象,采用密度泛函的赝势平面波法,在优化驰豫的基础上计算其电子结构和弹性模量,系统分析成分对各相电子结构的变化及脆性的影响。结果表明:Al含量逐步增多导致Al2p—Ti3d成键并抑制Ti—Ti键,使共价键以及成键的各向异性增强,因而使合金脆性增大;Mn替代Al位掺杂后,可减少Al—Al共价键,抑制Al2p—Ti3d成键并增强Mn与Ti的3d电子层杂化程度,降低由Al—Al共价键和Al2p—Ti3d杂化键形成所带来的键的空间各向异性和高位错能垒,进而改善合金的室温脆性。     

LF炉精炼渣冶金性能的研究现状

主要从精炼渣组分对其发泡性能和脱硫性能的影响二个方面综述了精炼渣的研究现状，展望了精炼渣的发展前景和方向，为今后精炼渣的研究和使用提供依据和参考。     

超细WC-Co硬质合金的磁性能和金相分析

介绍了超细WC-Co硬质合金的磁性能和金相,对它们之间的关系和作用进行了比较分析,认为磁性能和金相是超细WC-Co硬质合金质量控制的重要检测方法。     

五氯化钼

简单介绍了五氯化钼的应用、化学性能和物理性能.     

30万,60万千瓦汽轮机紧固件用高温合金的研究

本文研究了GH26合金成分中最佳碳钛含量,抗应力松弛性能、抗蠕变性能和抗应力腐蚀性能,合金组织和在使用温度下长时时效后组织稳定性。合金制作的紧固螺栓和汽封弹簧片等部件已用于国产首台引进60万千瓦汽轮机组上。     

V含量对TaVCN复合膜微结构、力学性能和摩擦磨损性能的影响

采用多靶磁控溅射技术,制备一系列不同V含量的TaVCN复合膜。利用X射线衍射仪、纳米压痕仪和高温摩擦磨损仪研究该复合膜的微结构、力学性能和摩擦磨损性能。结果表明, TaVCN复合膜为面心立方和底心斜方的双相结构。随V含量增加,复合膜的硬度先升高后降低,当V原子分数为26.85%时,复合膜的硬度达到最大值,为31.7 GPa。室温下随V含量增加,复合膜的摩擦因数和磨损率均先减小后增大,V原子分数为32.60%时,摩擦因数达到最小值,为0.213;V原子分数为26.85%时,磨损率达到最小值,为2.1×10?7 mm2/N。随温度升高,复合膜的摩擦因数逐渐减小,磨损率逐渐增大。并对不同温度下 TaVCN 和 TaCN 复合膜的摩擦磨损性能进行了讨论。     

Review of the historical, empirical, and theoretical status of the von Restorff phenomenon.

The major purpose of the review was to examine theoretical and empirical properties of the von Restorff phenomenon. A selection of studies that preceded the von Restorff article demonstrated that isolating an item by making it more vivid than the rest of the list yielded a positive influence on learning that item. Subsequent studies in a variety of contexts have been quite consistent in confirming that isolation facilitates learning of the isolated item. This review attempts to indicate some of the specific features and influences of the von Restorff effect. The final section of the article presents theoretical discussions and suggested attempts to explain the isolation effect. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling the Mechanical Behavior of Lung Tissue at the Microlevel

This paper is concerned with the development of a computational model of pulmonary alveoli against the background of ventilator-induced lung injuries. In order to quantify mechanical stimulation of alveolar tissue during artificial respiration, a detailed constitutive model of alveolar septa and an approach to consider interfacial phenomena is needed. For that purpose, a polyconvex hyperelastic material model formerly developed for arteries is adopted for pulmonary alveoli. Information about tissue morphology is inherently integrated into the constitutive model, therefore, establishing a connection between structure and function of the different septal constituents. Structural and interfacial dynamics are directly coupled at the alveolar surface. In order to take into account the complex behavior of surface active agents covering alveoli, a constitutive model considering dynamical changes of surface energy is employed.     

Nd-doped ZnO as a multifunctional nanomaterial

Chemically synthesised ZnO and Nd-doped ZnO nanoparticles were investigated for structural, optical, magnetic properties along with photocatalytic activity. Transmission electron microscopy measurement was performed on the undoped and doped ZnO nanoparticles. Compared to the undoped ZnO, Nd-doped ZnO nanoparticles showed enhanced photoluminescent and ferromagnetic properties. The Nd-doped ZnO nanoparticles also showed improved photocatalytic properties compared with the undoped ZnO nanoparticles. Furthermore, the effect of UV light irradiation was studied with thermoluminescence (TL) and photoluminescence (PL) measurement techniques. It was found that in case of Nd-doped ZnO nanoparticles TL intensity increased while the green emission in PL spectra decreased with UV-light irradiation. This was attributed to the production of more surface defects on UV irradiation on Nd-doping.     

Effect of Nd2O3 doping on the electrical properties of Ba0.96Ca0.04Ti0.90Sn0.10O3 ceramics

The Ba_(0.96)Ca_(0.04)Ti_(0.90)Sn_(0.10)O_3-xNd_2 O_3(x = 0-0.08%) ceramics were prepared via traditional solid-state sintering method. The influences of Nd3+ substitution on the phase structure, dielectric properties,piezoelectric and ferroelectric properties of the ceramics were investigated. All the samples possess pure BaTiO_3-type perovskite structure. MPB with orthorhombic and tetragonal phase coexist at around x = 0.03-0.04. Nd~(3+) doping decreases both Tc and T_(O-T) to lower temperature. All the samples exhibit an intermediate state with the coexistence of ferroelectric and diffuse relaxor ferroelectric behavior with the addition of Nd~(3+). The electric properties of the ceramics were optimized at x = 0.03 with d33, K_p, ε_r and P_r values of 545 pC/N, 51.9%, 24,412 and 10.74 μC/cm~2.     

Influence of alloying elements and grain refiner on microstructure,mechanical and wear properties of Mg-Al-Zn alloys

In the present investigation, the effects of alloying elements (Sn, Pb) and grain refiner (Ag, Zr) on microstructure, mechanical and wear properties of as-cast Mg-Al-Zn alloys were studied. The alloys were prepared through melting-casting route under a protective atmosphere and cast into a permanent mould. The microstructure of the base alloy consisted of α-Mg, Mg₁₇Al₁₂ continuous eutectic phase at the grain boundary and Mg-Zn phase was distributed within the grains. Addition of Sn and Pb suppressed the formation of continuous Mg₁₇Al₁₂ eutectic phase and formed Pb enriched Mg₂Sn precipitates at the grain boundary as well as inside the grain. The Ag and Zr addition to Mg-Al-Zn-Sn-Pb alloy suppressed the Mg₁₇Al₁₂ phase formation and refined the grains leading to improve mechanical properties. Addition of Sn, Pb and grain refiner (Ag, Zr) significantly enhanced the tensile strength and elongation but reduced hardness. The Ag addition imparted best tensile properties, where ultimate tensile strength (UTS) and elongation are 205?MPa and 8.0%, respectively. The fracture surfaces were examined under SEM which revealed cleavage facets and dimple formation. Therefore, the cleavage fracture and dimple rupture were considered as the dominant fracture mechanisms for developed Mg alloys. The cumulative volume loss of Mg alloys increased with sliding distance and applied load. The coefficient of friction decreased with sliding distance. The microscopic observation, analysis of the wear surface and coefficient of friction revealed that the wear mechanism of developed Mg alloys changes from abrasion oxidation to delamination wear.