材料期刊网

STUDY OF THE MICROSTRUCTURE AND PROPERTIES OF SIMULATED HEAT AFFECTED ZONE IN LASER WELDING OF ULCB 600 STEEL

Q. F. Wang , J. H. Liu , Z. Y. Li , P. H. Li , G. F. Zhou and X. Chen( 1) Huazhong University of Sci. & Tech. , Wuhan 430074 , China 2) Technology Center of WISCO , Wuhan 430080 , China)

金属学报(英文版)

The microstructure and properties of stmulated heat affected zone (HAZ) of laser welded ULCB600 steel were investigate by applying the simulation technique with gleeble - 2000 dynamic thermal - me - chanical simulator.The influence of the preheat condition on the microstructure and properties of simu- lated HAZ of laser welded plate was also studied in order to evaluate the feasibility of reducing arisk that the ductility and toedness of HAZ may be poor by using preheat treatment.The results indicate that the grain size of laser - welded HAZ simulated is very small no matter if there is preheat, the toughness of simulated HAZ is therefore improved comparing to the base metal,and there is no obvious brittle - ductile transition in the range from - 80℃ to 20℃. The TEM analyses of sub -microstruc- ture also discover that microstructure constituent of both simulated HAZ is dominative lath martensite. However, the shaf of martensite is relatively coarse,and the dislocation density is relatively high for simulated HAZ with 200℃ preheat because of slower cooling rate. Combination of these tow factors is responsible for farer bardness and better toughness of simulated HAZ with preheat condition.

关键词: physical simulation laser beam welding , null , null

HEAT TRANSFER BEHAVIOR OF SUPERALLOY DROPLETS DURING SPRAY FORMING

J.F. Sun , J. Shen , Z. Y. Li , J. Jia and Q.C. Li National Key Laboratory of Metal Precision Hot Processing , Harbin Institute of Technology , Harbin 150001 , China

金属学报(英文版)

Based on the Newtonian heat transfer formulation and classical heterogeneous nucleation theory, a mathematical model has been established to predict the profile of flight velocity, heat transfer coefficient, temperature, solid fraction and cooling rate of atomizing droplets for a superalloy. The results indicated that above parameters change with different droplet size and flight distance. The changing trend as well as the mechanism for the change are described and discussed.

关键词: spray forming , null , null , null

快速凝固Al—Li─Cu—Mg—Zr合金中H相和Z相的TEM研究

张立春 , 何安强 , 叶恒强 , 张永昌

材料研究学报

用HRTEM、TEM及EDAX分析研究了Al─Li—Cu—Mg—Zr合金中的一种新相(暂名H相)和六角Z相的结构,确定H相具有四方点阵,点阵参数为α=2.8nm,c=2.4nm,EDAX分析表明H相和Z相均含Al、Mg、Cu发现H相与Z相的共存取向关系为[100]‖[1120]Z,[1010]H‖[0001]Z。还观察到Z相中一种特有的旋转畴结构

关键词: Al─Li─Cu─Mg─Zr合金.四方H相 , tetragonal H phase , hexagonal Z phase

快速凝固Al-Li-Cu-Mg-Zr合金中Z相和T相的结构关系

张立春 , 何安强 , 吴玉琨 , 叶恒强 , 张永昌

金属学报

利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成

关键词: Al-Li-Cu-Mg-Zr合金 , Z hexagonal phase , T f.c.c. phase , shear structure

SOFC阴极材料(La_(0.85)Sr_(0.15))_y(Mn_(1-z)Cr_z)O_3的物理性能和化学稳定性

杨威 , 隋智通

材料研究学报

采用烧结法制备阴极材料(La0.85Sr0.15)y(Mn1z-Crz)O3(y=0.85;1;z=0.1,0.2).研究了多孔锰酸镧与致密ZrO2(8mol%Y2O3)界面的成分变化和显微形貌(La0.85Sr0.15)(Mn0.9Cr0.1)O3呈现高电子电导率、良好的热膨胀系数匹配和化学稳定性而(La0.85Sr0.15)MnO3未起到阻止界面退化的作用在1300～1500℃范围内Mn、La、Zr和Sr发生扩散,其中Mn的扩散明显

关键词: SOFC , lathanum manganite. chemical stability , thermal expansion , conductivity , null

Li+掺杂对Y2SiO5∶Pr3+上转换发光性能影响

刘成 , 杨毅 , 韩正玉 , 武晓雅 , 翁景霞 , 林璐

中国稀土学报 doi:10.11785/S1000-4343.20130408

采用溶胶-凝胶法制备Li+掺杂改性的Y2SiO5:Pr3+上转换发光材料,考察了Li+掺杂对样品晶型及发光性能的影响.采用XRD,DSC-TGA,FS对所制备的材料进行表征,结果表明Li+掺入浓度在7％～ 8％(摩尔分数)之间会引起Y2SiO5晶体类型由X型转变为X2型,且Li+掺入后样品转晶型温度由950℃降至800℃;样品经800℃煅烧处理后以X1型Y2SiO5为主相,850℃煅烧处理后以X2型Y2SiO5为主相;Li+掺入同时会提高Y2SiO5:Pr3+材料的上转换发光强度,Li+最佳掺杂浓度为10％,对于双掺杂pr3+,Li+:Y2SiO5体系中pr3+最佳掺杂浓度为1.2％.

关键词: 溶胶-凝胶法 , 上转换 , 晶相转变 , 锂掺杂 , 稀土

Y 对8090Al-Li 合金拉伸性能和断裂行为的影响

桂全红 , 马禄铭 , 蒋晓军 , 梁国军 , 李依依

材料研究学报

研究了两种不同Y 含量对8090Al-Li 合金拉伸性能及断裂行为的影响。实验表明:加入0.1wt-%Y 可在不降低强度的情况下提高合金的塑性,加入0.5wt-%Y 可在不降低塑性的情况下提高合金的强度。在峰值时效条件下,不加Y 的合金断裂为穿晶韧窝型和沿晶塑性混合方式,并伴有沿晶二次裂纹,加0.1%Y 不改变合金断裂模式,但使沿晶成分减少;加0.5%Y 合金则发生快速剪切断裂。本文从晶粒结构角度对断裂行为提出了解释。

关键词: A—Li 合金 , rare earth element Y , tensile properties , intergranular fracture , transgranular fracture

添加Y对Mg-3.5%Li合金冲击变形行为的影响

沙桂英 , 刘翠云 , 刘腾 , 孙晓光 , 李根

材料工程 doi:10.3969/j.issn.1001-4381.2010.07.014

利用Hopkinson压杆技术对Mg-3.5%Li及Mg-3.5%Li-0.77%Y合金在不同应变率下进行了冲击压缩实验,分析了两种合金的动态应力-应变行为及其应变率效应.结果表明,随应变率提高,Mg-3.5%Li合金的应力-应变行为表现出应变率强化效应与应变率弱化效应的双重特性.添加稀土元素Y后,合金有所强化,但其应力-应变行为仍具有应变率弱化效应,随应变率提高产生的微裂纹引起的内部损伤是导致合金应变率弱化效应的主要原因.

关键词: Mg-Li合金 , Mg-Li-Y合金 , 应变率 , 微裂纹

Mechanism of upconversion emission enhancement in Y(3)Al(5)O(12):Er(3+)/Li(+) powders

稀土学报(英文版)

Er(3+) and Li(+) codoped Y(3)Al(5)O(12) (YAG) powders were prepared for a systematic investigation of their upconversion emissions. X-ray diffraction (XRD), upconversion emission spectra, pump power dependence, FT-IR spectra and decay time were studied to characterize the samples. With Li+ doping, the upconversion emission intensity of Er(3+) doped YAG powders was obviously enhanced, accompanied with an increase in the ratio of green to red intensity. The enhancement of emission intensity could be attributed to two mechanisms: one was the distortion of local crystal field around Er(3+), and the other was the decrease in the amount of CO(3)(2-) and OH(-) groups. Our results revealed that the latter was the dominant mechanism of the upconversion intensity enhancement in the YAG:Er(3+)/Li(+) powders.

关键词: luminescence;optical materials and properties;sol-gel preparation;nanomaterials;rare earths;nanocrystals;nanophosphors;li+

Mg-12Li-3Gd-3Y-0.6Zr镁合金的均匀化研究

冯剑 , 黄金亮 , 贾玉鑫

兵器材料科学与工程

为改善铸态Mg-12Li-3Gd-3Y-0.6Zr合金的力学特性，对铸锭进行均匀退火处理。采用金相显微镜、SEM、XRD、显微硬度测试和拉伸力学特性测试，观察和研究了试验合金的微观组织和力学特性。结果表明：最佳的均匀化退火工艺为500℃×8 h，均匀化退火后合金的抗拉强度由铸态的114 MPa提高到133 MPa。第二相形态及分布的改变是Mg-12Li-3Gd-3Y-0.6Zr合金力学特性改变的主要原因。

关键词: 镁锂合金 , 均匀化 , 微观组织 , 力学特性