材料期刊网

TEM STUDY OF C-B_4C-SiC COMPOSITES WITH SILICON ADDITIVE

ZHAO Lihua , WU Lijun , HUANG Qizhong , YANG Qiaoqin 1)(Material Research and Test Center , Hunan University , Changsha , China)2)(Powder Metallurgy Research Institute , Center-South University of Technology , Changsha , China)3)(Laboratory of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Science , Shenyang , China)Manuscript received 18 April 1995

金属学报(英文版)

C-B4C-SiC composites with silicon additive obtained by the hot press sintering method are studied by means of transmission electron microscopy(TEM).When the specimens are heated to 1800℃,their structure does not change.When the specimens are heated to 2000℃,carbon begins to graphitize. Moreover,two monoclinic phases are observed.One monoclinic phase named as the M phase belongs to C-center monoclinic lattice with a=0.90nm,b=0.59nm,c=0.54nm and β=119.3°.The other monoclinic phase named as the Ml phase also belongs to C-center monoclinic lattice but with a=0.85nm,b=0.49nm,c=0.53nm and β=123.6°.

关键词: :C-B_4C-SiC composite , null

STRUCTURE OF Al-Mn-Zn-Mg ALLOY POWDER

WU Lijun , ZHAO Lihua , YANG Qiaoqin , LI Shaolu , LI Xieqian(Materials Research and Test Centre , Hunan University , Changsha 410082 , China)(Laboratory of Atomic Imaging of Solids , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China)

金属学报(英文版)

The structure of Al-Mn-Zn-Mg alloy powder annealed at 800℃ has been studied by transmisston electron microscopy(TEM).An approximant phase(named as C-phase) to the decagonal phase was found and its crystal structure was determined It belongs to c-center orthorhombic lattice with a=2.35 nm,b=3.27 nm and c=1.22 nm.We stillfound a hexagonal phase with a=0.7) nm and c=0.79 nm,(named as phase) in the annealed alloy powder.The annealed alloy powder is composed of the C-phase,the phase,the decagonal phase and Al solid solution.

关键词: :quasicrystal , null , null

1998 COMPREHENSIVE TABLE OF CONTENTS

中国腐蚀与防护学报

N。1Atmospheric Corrosivlty for Steels………………………………………………… .LIANG Caideng HO[I i。-tat（6）Caustic Stress Corrosion Cr。king of Alloy 800 Part 2.The Effect of Thiosul执e……………………………………… KONG De-sheng YANG Wu ZHAO Guo-zheng HUANG De.ltL。ZHANG Yu。。he CHEN She。g-bac（13）SERS slid E16CttOCh6iniC81 Stlldy Of Illhibit1Oli M6ch＆tllsth Of ThlollY68 Oil ITOll ID H....

关键词:

Noncollinear magnetic ground state of PrFeAsO

Europhysics Letters

Noncollinear magnetic investigations of the ground state in PrFeAsO have been performed by the density-functional theory. We calculated the total energy and made structure optimization, and the electronic density of states of PrFeAsO was analyzed. There are three different magnetic structures in PrFeAsO defined by experiments. Based on these magnetic structures, we studied four collinear and four noncollinear cases. The ground state is found to take the ordering proposed by Zhao, in which the FeAs plane is of stripe antiferromagnetism and Pr spins are perpendicular to Fe spins. The electronic density of states indicates that for PrFeAsO the increase of the electron Coulomb interaction leads to a decrease in conductivity. Copyright (C) EPLA, 2011

关键词: high-temperature superconductivity;phase-diagram;oxypnictides;instability

硝酸羟胺的热稳定性评估及热分解机理研究

刘建国 , 安振涛 , 张倩 , 杜仕国 , 姚凯 , 王金

材料导报 doi:10.11896/j.issn.1005-023X.2017.04.030

为评估氧化剂硝酸羟胺的热稳定性,使用标准液体铝皿于3 K/min、4 K/min、5 K/min加热速率下进行热分析.借助非等温DSC曲线的参数值,应用Kissinger法和Ozawa法求得热分解反应的表观活化能和指前因子,根据Zhang-Hu-Xie-Li公式、Hu-Yang-Liang-Xie公式、Hu-Zhao-Gao公式以及Zhao-Hu-Gao公式,计算硝酸羟胺的自加速分解温度和热爆炸临界温度,并对热分解机理函数进行了研究.设计了7条热分解反应路径,采用密度泛函理论B3LYP/6-311++G(d,p)方法对硝酸羟胺的热分解进行了动力学和热力学计算.计算结果表明,硝酸羟胺热分解的自加速分解温度TsADT=370.05 K,热爆炸临界温度Te0=388.68K,Tbp0=397.54 K,热分解最可几机理函数的微分形式为f(a) =17×(1-α)18/17.硝酸羟胺热分解各路径中,动力学优先支持路径Path 6、Path 5、Path 4和Path 1生成NO和NO2,其次是Path 2、Path 7和Path 3生成N2和N2O.温度在373 K以下时,Path 1'反应无法自发进行,硝酸羟胺无法进行自发的热分解.从热力学的角度来看,硝酸羟胺在370.05K以下储存是安全的.

关键词: 硝酸羟胺 , 热分析 , 热稳定性 , 热分解机理 , 密度泛函理论