材料期刊网

Thermodynamic Calculation of Segregation in Multicomponent Steels

Lin LI (Dept. of Materials Science & Engineering , Shanghai University , Shanghai 200072 , China)L.Delaey P.Wollants and V.D.Biest (Dept. of MTM , Katholieke Universiteit Leuven de Croylaan , 3001 , Heverlee , Belgium)(To whom correspondence should be addressed)

材料科学技术（英文）

The thermodynamic equation for segregation in multicomponent steels is extended from that in ternary system and the segregation amounts of Cr, C and P in the intergranular phase in a Cr-steel are estimated.

关键词:

R&D STATUS ON INTERMETALLICS IN CHINA

CHEN Guoliang(State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 , China)SHI Changxu (Academia Sinica , Beijing 100864 , China)

金属学报(英文版)

This paper briefiy introduces the R&D of intermetallics in China. R&D on intermetallics in a national scale in China began near ten years ago. The investigation in past years focused on the fundamental research and materials development. A significant progress has been made. Various components that made of Ti3Al Ni3Al, TiAl and Fe3Al have been successfully manufactured Some of them have been evaluted. It is expected that some intermetallic alloys will be produced in an industrial scale in the near future.

关键词: :intermetallic alloys , null , null , null

Key R&D activities for development of new types of wrought magnesium alloys in China

Transactions of Nonferrous Metals Society of China

Many researchers in China are actively engaged in the development of new types of wrought magnesium alloys with low cost or with high-performances and novel plastic processing technologies. The research activities are funded primarily through four government-supported programs: the Key Technologies R&D Program of China, the National Basic Research Program of China, the National High-tech R&D Program of China, and the National Natural Science Foundation of China. The key R&D activities for the development of new wrought magnesium alloys in China are reviewed, and typical properties of some new alloys are summarized. More attentions are paid to high-strength wrought magnesium alloys and high-plasticity wrought magnesium alloys. Some novel plastic processing technologies, emerging in recent years, which aim to control deformation texture and to improve plasticity and formability especially at room temperature, are also introduced.

关键词: wrought magnesium alloy;microstructure;properties;alloy designing;plastic deformation;research projects;y-zr alloys;mechanical-properties;mg-4y-4sm-0.5zr alloy;grain-refinement;rare-earth;microstructure;gd;phase;temperature;evolution

聚D,L-乳酸中间体--D,L-丙交酯的合成

王华林 , 方大庆 , 史铁钧 , 翟林峰

高分子材料科学与工程

聚D,L-乳酸(PDLLA)的合成方法主要有直接法和间接法两种.间接法合成PDLLA的关键在于中间体D,L-丙交酯(DLLA)的制备.文中以D,L-乳酸为原料,在催化剂辛酸亚锡(ZnOct2)的作用下,合成DLLA.研究温度、压力、时间等因素对DLLA产率的影响,利用DSC、XRD、IR等分析测试技术对DLLA的性能和结构进行相关的测试和表征.研究结果表明,在反应体系中加入乙二醇作为稀释剂,能降低DLLA的馏出温度,避免了DLLA在蒸馏过程中产生炭化现象,并使DLLA的平均产率由36.8%提高至51.3%.

关键词: 聚D,L-乳酸 , D,L-丙交酯 , 合成

聚D,L-乳酸的体外可降解性能

舒静 , 任丽丽 , 王鹏 , 王鉴 , 王刚

高分子材料科学与工程

研究了中等分子量((M)η=1.10×105)的聚D,L-乳酸在体外不同环境中的可降解性能,包括不同pH值溶液(37℃)和自然土壤.降解性能采用失重率、分子量变化、溶液pH值变化等来进行评价,并对试样表面形貌采用扫描电镜(SEM)进行了观察.结果表明:聚D,L-乳酸在体外环境中具有良好的可降解性,受降解环境的影响较大;失重和分子量的减小并不平行;在不同pH值溶液和土壤中的分子量变化在一定时间内符合一级反应动力学,且随溶液pH值的增大,降解速率减小.

关键词: 聚D,L-乳酸 , 体外可降解性 , 降解动力学

The behavior of 3d electrons and defects in TiAl-based alloys containing V and Cu studied by positron annihilation

Science in China Series G-Physics Astronomy

Information of defects and 3d electrons in transition metals (Ti, V, Cu) and TiAl-based alloys (Ti(50)Al(50), Ti(50)Al(48)V(2), Ti(50)Al(48)Cu(2)) can be extracted from the positron lifetime and coincidence Doppler broadening spectra. The results show that the 3d electron signals for the transition metals Ti, V and Cu increase with the number of 3d electrons. The 3d electron signal and the electron density for binary TiAl alloy are relatively low due to the (Ti)3d-(Al)3p interactions. The addition of V and Cu atoms to TiAl alloy leads to the increase in the electron densities in bulk and the defects on grain boundaries simultaneously, as well as the enhancement of the 3d electron signal. The 3d electron signal in the spectrum of Ti(50)Al(48)Cu(2) alloy is higher than that of Ti(50)Al(48)V(2) alloy.

关键词: TiAl alloy;3d electron;defect;positron annihilation;intermetallic compounds;plastic-deformation;ni3al alloys;cr;densities;electrons;compound;bulk;semiconductors;identification

混合溶剂热法制备[Zn(L-trp)(D-trp)]n

王建 , 许兴友 , 马卫兴 , 赵宏 , 陆路德 , 杨绪杰 , 汪信

人工晶体学报

新型氨基酸配位聚合物[Zn(L-trp)(D-trp)]n(L-trp和D-trp分别是L-色氨酸和D-色氨酸)通过水热法制备,并进行元素分析、红外光谱、单晶X-衍射等的表征.该化合物属三斜晶系,P-1,a=0.91670(10)nm,b=0.53320(6)nm,c=1.9525(2)nm,Z=2.为二维双链平面结构.此配位聚合物具有中心对称空间群.每个锌离子Zn2+与一对外消旋体配合,而形成内消旋化合物.

关键词: 色氨酸 , Zn(Ⅱ)配位聚合物 , 混合溶剂热法 , 表征

（L12,D022）-TiAl3和L12-Ti（Al,Pt）3电子结构与光学性质第一性原理计算

段永华 , 孙勇 , 鲁俐

功能材料 doi:10.3969/j.issn.1001-9731.2013.24.016

基于密度泛函理论(DFT)的第一性原理赝势平面波方法,采用广义梯度近似(GGA),计算了立方结构 L12-TiAl3和 L12-Ti (Al,Pt)3及四方结构D022-TiAl3的电子结构与光学性质。计算结果表明L12-TiAl3和D022-TiAl3费米能级附近价带和导带主要是由Ti的3d 和 Al 的3p 轨道贡献,而 L12-Ti(Al, Pt)3费米能级附近价带和导带则主要是由Ti的3 d和Pt的6 s 轨道贡献；同时也计算了 L12-TiAl3、L12-Ti (Al,Pt)3和D022-TiAl3的介电函数、折射率、吸收系数和反射率等。

关键词: L1 2-Ti (Al,Pt)3 , 第一性原理 , 电子结构 , 光学性质

First-principles investigation of 3d transition elements in L1(0) TiAl

Journal of Applied Physics

The effect of 3d transition elements (such as V, Cr, Mn, Fe, Co, and Ni additions) on material properties in L1(0) TiAl has been studied using the first-principles DMol and discrete variational method within the framework of the density-functional theory. The transfer energy calculation indicates that all these 3d elements show a tendency to substitute for Al sites in the stoichiometric TiAl alloy, with the increasing order V < Cr < Mn < Ni < Fe < Co. Our results show that the local distortion of crystal lattice around an impurity atom is nonuniform, and it is found that the important influencing factors on the local lattice distortion are the impurity atom size and the site preference. Based on the effects of the doped alloying elements on the structural parameters and mechanical properties, we conclude that the larger bond strength and the smaller axial ratio benefit the ductility. (c) 2007 American Institute of Physics.

关键词: alloying elements;site preference;electronic-structure;mn;substitutions;base alloys;compound;nb;deformation;occupancies;aluminides

Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

Applied Surface Science

High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density (I(corr)) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated. (C) 2011 Elsevier B. V. All rights reserved.

关键词: AZ91D Mg alloy;Electrodeposition;Ni-P;Corrosion resistance;phosphorus incorporation;pure magnesium;thin-films;ni;pretreatment;deposits;behavior;copper