采用电化学阻抗谱测试技术、光学显微镜、扫描电镜及X射线能谱研究了V-5Cr-5Ti合金在Cl-溶液中的界面腐蚀特性，并与钒进行了比较。结果表明，在50μg/g Cl-的KCl溶液中，V与V-5Cr-5Ti合金的电化学阻抗谱均具有容抗弧特性，其界面腐蚀物理结构模型可用 R1（Q1（R2（Q2 R3）））等效电路表示，V的腐蚀电极过程电荷转移电阻远大于V-5Cr-5Ti合金；V的腐蚀为均匀腐蚀，而V-5Cr-5Ti合金为局部腐蚀；V的抗腐蚀性能优于V-5Cr-5Ti合金。

Interface corrosion characteristics of V-5Cr-5Ti alloy in chloride solution were studied by electrochemical impedance spectroscopy (EIS) ,optical microscope ,scanning electron microscope (SEM ) and X-ray energy dispersive spectroscope (EDS ) , and compared with that of V .The results indicate that in 50 μg/g Cl- potassium chloride solution ,EIS of V and V-5Cr-5Ti alloy has same capacitance arc characteristic ,their interface corrosion physical structure model can be represent as equivalent circuit as R1 (Q1 (R2 (Q2 R3 ))) .Charge transfer resistance of corrosion electrode process of V is much higher than that of V-5Cr-5Ti alloy .Interface corrosion characteristic of V is homogeneous ,but V-5Cr-5Ti alloy is localized .Corrosion resistant performance of V is better than that of V-5Cr-5Ti alloy .

Ti-5553(Ti-5Al-5V-5Mo-3Cr-0.5Fe)合金具有优异的综合力学性能,正逐步替代TC4(Ti-6Al-4V)钛合金成为高强度航空用工件的制备材料。然而,由于Ti-5553合金机械加工效率低,一定程度上制约了其在航空领域的大规模应用。为此,对Ti-5553合金与TC4钛合金的车削加工性能参数进行了探索,发现在相同的切削速度下,Ti-5553合金的主切削力和吃刀抗力均高于TC4钛合金,且最高切削速度仅为50 m/min。此外,两种合金在切削过程中均会与车刀发生扩散反应,而Ti-5553合金对刀具的磨损更为严重。相信本研究将为后期优化Ti-5553合金的车削加工参数、提高其加工效率提供有利的实验数据支持。

Ti-5553(Ti-5Al-5V-5Mo-3Cr-0.5Fe) alloy has excellent comprehensive mechanical properties , and it is substituting for TC4 ( Ti-6Al-4V) titanium alloy to produce the high strength workpieces in aviation .However, due to the lower machining efficiency of Ti-5553 alloy, the use in the industry of aviation is restricted .So the parameters in cutting process of Ti-5553 alloy and TC4 titanium alloy were achieved by experiment .The results show that the cutting force of Ti-5553 alloy is higher than TC4 titanium alloy under the cutting speed , and the maximum allowed speed is only 50 m/min for Ti-5553 alloy .Besides , the diffusion reactions both have occurred during the cutting processes . This research will give an experimental data support to optimize the cutting processing parameters and increase the machining efficiency .

尖晶石结构的Li4 Ti5 O12由于电压平台平稳、循环寿命长、“零应变”和安全性高等优点，成为锂离子电池的热门负极材料。然而纯Li4 Ti5 O12本身为绝缘体，导电性很差，倍率性能不佳，这限制了它的实际应用。研究表明，对Li4 Ti5 O12表面进行碳包覆可以有效改善其电化学性能。结合最近国内外研究情况，综述了表面碳包覆对Li4 Ti5 O12负极材料改性的研究进展，分析了不同的碳包覆方法、碳层厚度、碳结构和碳含量对Li4 Ti5 O12/C复合材料电化学性能的影响，希望促进Li4 Ti5 O12/C复合电极材料在锂离子电池领域的应用。

ABSTRACT:Spinel Li4 Ti5 O12 has become a promising anode material for lithium ion batteries because of its flat voltage, long cy-cle life,"zero starin" and high safety. However, the electronic conductivity of pure Li4 Ti5 O12 is very low, leading to bad rate per-formance, which limits its practical application. Studies have proven that carbon coating on Li4 Ti5 O12 can effectively enhance the electrochemical performance. In this review, we summarized the recent developments of modification of Li4 Ti5 O12 anode material by carbon coating based on the studies in China and foreign countries. Moreover, the effects of different coating methods, carbon coat-ing thickness, carbon structure and carbon content on the electrochemical properties of the Li4 Ti5 O12/C composite were analyzed, shedding light on the further application of the Li4 Ti5 O12/C composite as high-performance anode of lithium ion batteries.

采用基于密度泛函理论(DFT)的第一性原理赝势平面波方法,计算了不同数量的Al原子代位六方D88结构的Ti5Si3晶体中的Si原子后的形成能(ΔHf)、结合能(ΔEcoh)、体模量(B)、剪切模量(G)、泊松比(ν)、Cauchy压力参数(C12―C66,C13―C44)、金属性(fm)和派-纳力(τP-N)等参数,表征了Al合金化对D88-Ti5Si3的结构稳定性和力学性质的影响。结合态密度、差分电荷密度图和Mul iken布居等电子结构分析,揭示了Al原子的添加量对D88-Ti5Si3的韧/脆性变化的影响机制。研究表明, D88-Ti5Si3晶体中强的Ti6g―Si6g方向共价键是导致其室温脆性的主要原因。当1个和2个Al原子占据D88-Ti5Si3晶体中Si6g位置时,形成了键强较弱的Al6g―Si6g键、Ti6g―Al6g键和Ti4d―Al6g键,同时降低了D88-Ti5Si3中Ti6g―Si6g键的强度和数量,从而提高了D88-Ti5Si3的韧性。当D88-Ti5Si3晶体中Si6g位置被3个Al原子所占时, Al6g―Si6g键消失,而Ti6g―Si6g键的强度增加,导致Ti5(Si1-xAlx)3的脆性增加。

The influence of the substitution of Al for Si on the structural stability and mechanical properties of D88-Ti5Si3 was determined using first-principles pseudopotential plane-wave methods based on density functional theory. Several parameters including formation enthalpies ((ΔHf), cohesive energies (ΔEcoh), bulk modulus (B), shear modulus (G), Poisson′s ratio (ν), Cauchy′s pressure (C12-C66,C13-C44), metal icity (fm), and Peierls stress (τP-N) were calculated. To develop a better understanding of the effects of substitutional Al al oying on the toughness/brittleness of D88-Ti5Si3 from an electronic structure point of view the density of states, charge density differences and Mul iken population were determined. The results show that the intrinsic brittleness of D88-Ti5Si3 comes from strong covalent bonding between Ti6g and Si6g. When one or two Ti atoms occupy Si sites in the D88-Ti5Si3 crystal the intensity of covalent bonding between Ti6g and Si6g is reduced and the m

采用Ti/Al/Ti/Au多层金属电极对高Al组分n-AlxGa1-xN(x=0.6)欧姆接触的制备进行了研究,通过优化Ti接触层厚度以及合金退火条件,获得了较低的比接触电阻率(5.67×10-5Ω.cm2)。研究证实,Ti接触层厚度对欧姆接触特性有着重要影响,同时发现,高低温两步退火方式之所以能够改善欧姆接触特性的本质是与Al3Ti及TiN各自的生成条件直接相关,即低温利于生成Al3Ti,高温利于生成TiN,而这对n型欧姆接触的有效形成至关重要。

In this work,the ohmic contacts of Ti/Al/Ti/Au multilayer electrode to high Al-content Si-doped n-AlxGa1-xN（x=60%） were studied.By optimizing the thickness of Ti contact-layer and the annealing conditions,low specific contact resistivity of（5.67×10-5 Ω·cm2） was achieved.It is revealed the thickness of Ti contact-layer has great effect on the characteristic of ohmic contact,meanwhile the essential reason for achieving low resistance ohmic contact by two-step annealing method is that low temperature favors the formation of Al3Ti,and high temperature favors the formation of TiN,which is the key factor in forming n-type ohmic contact.