F. Huang N.R. Tao K. Lu
材料科学技术（英文）
The microstructures and hardness of pure Al samples subjected to plastic deformation with different temperatures and strain rates were investigated. The results showed that the strain-induced grain refinement is significantly benefited by increasing strain rate and reducing deformation temperature. The saturated size of refined subgrains in Al can be as small as about 240 nm in cryogenic dynamic plastic deformation (DPD). Grain boundaries of the DPD Al samples are low-angle boundaries due to suppression of dynamic recovery during deformation. Agreement of the measured hardness with the empirical Hall-Petch relation extrapolated from the coarse-grained Al implies that the low-angle boundaries can contribute to strengthening as effective as the conventional grain boundaries.
关键词:
Dynamic plastic deformation
,
Microstructure
,
Hardness
,
Strain rate
,
Temperature
F. Huang N.R. Tao K. Lu
材料科学技术（英文）
The microstructures and hardness of pure Al samples subjected to plastic deformation with different temperatures and strain rates were investigated. The results showed that the strain-induced grain refinement is significantly benefited by increasing strain rate and reducing deformation temperature. The saturated size of refined subgrains in Al can be as small as about 240 nm in cryogenic dynamic plastic deformation (DPD). Grain boundaries of the DPD Al samples are low-angle boundaries due to suppression of dynamic recovery during deformation. Agreement of the measured hardness with the empirical Hall-Petch relation extrapolated from the coarse-grained Al implies that the low-angle boundaries can contribute to strengthening as effective as the conventional grain boundaries.
关键词:
Dynamic plastic deformation
,
Microstructure
,
Hardness
,
Strain rate
,
Temperature
刘文鹏
,
张庆礼
,
杨华军
,
周鹏宇
,
孙敦陆
,
高进云
,
谷长江
,
罗建乔
,
王迪
,
殷绍唐
量子电子学报
doi:10.3969/j.issn.1007-5461.2011.02.018
采用固相反应法制备了Bi3+、Eu3+、Tb3+掺杂的Lu3TaO7.测量了样品的X射线衍射谱、激发和发射光谱及荧光衰减曲线.三种离子掺杂的Lu3TaO7均呈现出强的荧光发射,其中Bi3+具有峰位在431 nm处的一强发射宽带,衰减寿命为16.8μs,Eu3+、Tb3+则表现出稀土离子的特征锐发射峰,衰减寿命分别为1.26 ms和1.20 ms.因此,它们均是具有潜在应用前景的重闪烁体材料.
关键词:
材料
,
闪烁体
,
Lu3TaO7
,
发光
肖瑗
,
王哲飞
,
龚志杰
,
王丽熙
,
张其土
功能材料
采用固相合成法制备了(Y0.99R0.01)2 Ti2O7(R=Pr、Tb、Ho、Er、Tm、Yb、Lu)陶瓷,研究了Pr、Tb、Ho、Er、Tm、Yb及Lu掺杂对Y2Ti2O7陶瓷物相组成、烧结性能和微波介电性能的影响.结果表明A位取代能改进其微波介电性能.烧结样品为单相的烧绿石结构,主晶相为Y2Ti2O7.当R=Er,1450℃烧结4h时,(Y0.99Er0.01)2Ti2O7陶瓷的微波介电性能最佳:εr=44.3,Q×f=12021GHz(5.371GHz),τf=+44×10-6/℃,优于Y2Ti2O7陶瓷的介电性能(εr=54,Q×f=6565 GHz,τf=-31×10-6/℃).
关键词:
无机非金属材料
,
微波介质陶瓷
,
Y2Ti2O7
,
烧绿石结构
,
掺杂
张明举
,
李文明
,
郑树凯
中国有色金属学报
doi:10.19476/j.ysxb.1004.0609.2017.05.012
采用基于密度泛函理论(DFT)的第一性原理平面波超软赝势(PWPP)方法,模拟计算未掺杂,Lu、F单掺杂及Lu-F共掺杂ZnO的几何结构、能带结构、态密度分布、光吸收谱和介电常数等性质.结果表明:掺杂后ZnO的晶格常数发生畸变,晶胞体积增大,禁带宽度不同程度地减小;在光学性质方面,F单掺杂较Lu单掺杂和Lu-F共掺杂时在可见光区的吸收系数和反射低,反映前者在可见光范围具有较高的透射率.
关键词:
ZnO
,
第一性原理
,
共掺杂
,
电子结构
,
光学性质
Solid State Communications
Magnetic anisotropy fields at room temperature of ternary tetragonal compounds of R2Fe14C(R = Lu, Gd, Nd) and R2Fe14B(R = Gd, Nd) were determined by Singular-Point-Detection (SPD) technique. The magnetocrystalline anisotropies of the carbides were found to be larger than those of their corresponding borides, indicating that the outstanding permanent-magnetic properties may be obtained in the R2Fe14C-based alloys.
关键词:
Journal of Magnetism and Magnetic Materials
Magnetization curves of the ternary tetragonal compound Lu2Fe14C were measured in an extracting-sample magnetometer in the temperature range from 1.5 to 300 K. The temperature dependence of the magnetic properties of Lu2Fe14C is discussed.
关键词:
anisotropy
李秾
,
李洪波
,
张杰
,
贾生晖
,
褚玉刚
,
刘海军
钢铁
doi:10.13228/j.boyuan.issn0449-749x.20160554
为了揭示冷轧带材前屈曲面内残余应力与后屈曲挠度、后屈曲残余应力的关系,引入非协调F?ppl-von Kármán方程组,建立了两边自由无限长带条后屈曲的非线性偏微分方程组边值问题模型.根据冷轧带材后屈曲挠度具有轧制方向单波长周期性变化的特点,将非线性偏微分方程组边值问题分离变量而形成非线性常微分方程组边值问题.将边值问题中涉及的各物理量无量纲化,并分析这些物理量的数量级,进而确定出带有待定系数的无量纲挠度函数的形式.然后将总势能写成只与无量纲挠度函数有关的形式,并利用Ritz法确定各待定系数.最后采用其他文献中的计算结果与本文提出方法的计算结果进行对比,发现较为吻合,并解释了产生误差的原因.同时针对某冷轧厂产品计算出后屈曲释放后的残余应力,并计算了使带钢保持平直的最小张应力,为板形仪的合理应用提供了参考.
关键词:
冷轧带材
,
后屈曲
,
非协调F?ppl-vonKármán方程组
,
Ritz法
Pengfei Zhang Litong Zhang Xiaowei Yin
材料科学技术（英文）
To improve the corrosion resistance of porous Si3N4 used in the high temperature environments, which contain water vapor and volatile species, porous Si3N4-Lu2Si2O7 composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N2 atmosphere at the temperatures lower than 1550°C. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO2 derived by the oxidation of Si3N4 at 1250°C in air reacted with Lu2O3 at various sintering temperatures, leading to the formation of Lu2Si2O7 with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si3N4-Lu2Si2O7 composite ceramics with the porosity of 52% and the pore size of 0.2μm were obtained by oxidation bonding at 1250°C for 1 h and pressureless sintering at 1550°C for 2 h using 4 wt pct Lu2O3 additive.
关键词:
Porous ceramics
,
氮化硅
,
焦硅酸镥
,
无压烧结
材料科学技术（英文）
Fe/Ti multilayers with different modulation wavelengths (Lambda) prepared by r.f. sputtering has been investigated by using cross sectional transmission electron microscopy (XTEM). It was observed that the columnar structure, interface morphology, and metastable phase presented at the interface of the multilayer system strongly depend on the bilayer thickness (Lambda). For high period multilayers, the waviness wavelength of interfaces is about two times broader than the column diameter. For a sample with Lambda =30 nm, its column width and waviness wavelength was about 80, and 190 nm, respectively. Both of them decreased with the reduction of Lambda, so as to nearly equal values of column diameter and waviness wavelength were obtained. The Fe and Ti grains of both 30 nm and 6 nm multilayers are polycrystalline, and have a textured structure. In short bilayer thickness (Lambda =6 nm), the intermetallic compound Fe2Ti was presented at the interfaces due to solid state reaction; for Lambda =2 nm, amorphous phase Ti-rich layer was formed at the interfaces, resulting in a sharp interface multilayer structure.
关键词:
model;films
