Y.J. Li
,
J.S. Pan
,
M.J. Hu
,
D. Tian and W.M. Zhang Open Laboratory of the Educational Ministry for High Temperature Materials & Tests
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China
金属学报(英文版)
When FEM is utilized to simulate the quenching process of the workpiece and realize the coupled calculation of the temperature field and phase transformation, due to the effect of the complex shape, non-linear physical parameters and the latent heat during phase transformation, the element selection should be done cautiously so that end results can meet the actual situations. In this paper through comparing the different type and density of elements, the eight-node, hexahedral, isoparametric element is found to be a good choice. Using this kind of element can not only meets the need of calculating accuracy, but also cut down the calculating magnitude and takes full advantage of the hardware source. In addition, the effect of distorted elements on the calculation result has also been discussed in this paper.
关键词:
FEM
,
null
,
null
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
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
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
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+
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
Chemical Physics Letters
The influence of site occupancy of Li(+), including substitutional and interstitial sites, on the upconversion emissions of Er(3+) doped Y(3)Al(5)O(12) powders is reported. The intensity of green emission increases slightly when the Li(+) occupies substitutional site, but when the Li(+) enters into interstitial site it enhances drastically accompanied with a change of emission spectra. These phenomena originate from the increase, induced by interstitial Li(+), in the lifetime of (4)I(11/2) level, the ratio of radiation rate in green emission and the absorptivity at 980 nm. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
y2o3 nanocrystals;er3+;photoluminescence;ions
冯剑
,
黄金亮
,
贾玉鑫
稀土
为了提高Mg-8Li-3Gd-3Y-0.6Al合金铸锭的力学性能,对合金进行了均匀化退火处理.通过金相显微镜、扫描电镜、显微硬度测试、X射线衍射、拉伸力学性能测试等手段,研究了均匀化条件对Mg-8Li-3Gd-3Y-0.6Al合金的显微组织和力学性能的影响.结果表明,铸态合金经773K 8h的均匀化处理后,铸态时的网状相完全溶解到基体中,第二相弥散分布在基体中,同时退火态合金的抗拉强度达到了154 MPa,比铸态合金提高了23％.合金最佳的均匀化退火工艺是773K 8h,此时该合金具有较好的综合力学性能.
关键词:
Mg-8Li-3Gd-3Y-0.6Al合金
,
显微组织
,
均匀化
,
力学性能
徐春杰
,
马涛
,
王锦程
,
屠涛
,
张忠明
稀有金属材料与工程
采用锂盐熔剂保护熔铸了Mg-8Li-4Zn-xY合金铸锭,并通过正挤压制成1 mm的薄板.通过光学显微镜、扫描电镜、XRD分析及合金硬度测试,探讨合金的组织与力学性能.结果表明:Mg-8Li-4Zn-xY合金基体为β-Li(bcc)和α-Mg (hcp)相,析出强化相颗粒和化合物为Mg2Zn11,Mg72.05Zn27.g5,MgZn,Mg2Y,MgY及未知相.随Y含量的增加,铸态 基体组织得到细化,析出相数量增加.1 mm正挤压变形态薄板材基体组织大小、形貌和β-Li相内弥散析出的强化相颗 粒数量随着Y含量的提高没有明显变化,但α-Mg相由β-Li相包裹着被拉长并得到一定程度的细化,呈平行于挤压方向的条带状.β-Li相在协调塑性变形的同时发生了动态再结晶,晶界均匀分布着强化相颗粒.无论是铸态还是挤压后1 mm的Mg-8Li-4Zn-xY合金薄板,随着Y含量的增加合金得到不同程度的强化,硬度均得到不同程度的提高.
关键词:
Mg-Li合金
,
挤压
,
显微组织
,
力学性能
曲涛
,
田彦文
,
钟参云
,
翟玉春
功能材料
橄榄石型LiFePO4是近年发展起来的一种锂离子电池正极材料,它的理论容量为170mAh/g.具有价格便宜、环境友好、无毒、无吸湿性、热稳定性好等优点,越来越受到人们的重视.但是由于LiFePO4的室温电导率低,影响了它的实际应用,为改善其电导率低的问题,本文采用固相法掺杂稀土元素Y合成Li0.99Y0.01FePO4,结果表明,掺杂后材料具有良好的电化学性能,其室温初始放电容量为129.9mAh/g,循环15次后几乎没有衰减.
关键词:
锂离子电池
,
正极材料
,
Li0.99Y0.01FePO4
,
稀土
