材料期刊网

Characterization of ThMn_(12)-structure Stability

By GENG Mingming MA Ruzhang XU Zuxiong WANG Genmiao ** Dept.of Material Physics , University of Science and Technology Beijing , Beijing , 100083 , China*** Structure and Element Analysis Lab. , University of Science and Technology of China , Hefei , 230026 , China+ To w

材料科学技术（英文）

A series of YTi(Fe_(1-x)_(11)alloy with x=0.00,0.01,0.03,0.04,0.05,0.07 and 0.10 has been investigated by measurement of the structural properties and ~(57)Fe M(?)ssbauer experiments.The pure ThMn_(12)-structure phase exists at x≤0.03 and is absent at x>0.03.The reasons for lower satura- tion magnetization and lower energy product of the ThMn_(12)-structure compounds were given.The crystal structure relations between R_2Fe_(17)-structure and ThMn_(12)-structure were discussed.Comparing with the R_2Fe_(17)and R_2Fe_(14)B compounds,the ThMn_(12)-structure RFe_(12-x)M_x compounds have the same magnetic moment of Fe at x=0.The potential for increasing the saturation magnetization of ThMn_(12)-structure compounds may be enhanced by the addition of stabilization elements.

关键词: ThMn_(12)-structure stability , null , null

θ Correction to the Analytical Expressions for Calculating Activities from Phase Diagrams Involving Intermediate Compounds

XIE Fanyou ZHANG Fan ZHOU Guozhi ** Beijing University of Science and Technology , Beijing , 100083 , China*** Institute of Chemical Metallurgy , Academia Sinica , Beijing , 100080 , China+ To whom correspondence should be addressed

材料科学技术（英文）

A set of correct expressions for calculating activities and activity coefficients from binary phase diagrams involving intermediate compounds are presented in this paper by the introduction of a correct parameter θ. The application of these expressions to system Mg-Sn shows that they are quite feasible.

关键词: activity , null , null

Effect of Ga on Magnetic and Microstructural Properties of Nd-Fe-Co-B Alloys

PAN Shuming LI Guobao PING Jueyun MA Ruzhang ** General Research Institute for Non-ferrous Metals , CNNC , Beijing , 100088 , China.University of Science and Technology , Beijing , 100083 , China. To whom correspondence should be addressed.

材料科学技术（英文）

关键词: Ga addition , null , null , null

Alkali-metal Na Adsorption and Promoted Oxidation on Si(100)2×1 Surface

Shihong XU Pengshou XU Mingrong JI Xianming LIU Maosheng MA Jingsheng ZHU Yuheng ZHANG Structure Research Laboratory , University of Science and Technology of China , Hefei , 230026 , ChinaZhenjia XU Institute of Semiconductor , Academia Sinica , Beijing , 100083 , China

材料科学技术（英文）

The alkali-metal Na adsorption on Si(100)2×1 surface and its promoted oxidation and Si oxide growth have been investigated by means of thermal desorption,work function,Auger electron spectroscopy and photoemission electron spectroscopy.The experimental data showed that there was a new state,interface electron state,near the Fermi level after the deposition of Na atoms.It was found that the presence of Na always caused an increase of the oxygen initial uptake whereas the promotion of Si oxide growth was observed only at the coverage of Na greater than 0.5 ML.A new mechanism of Na-promoted Si oxide growth is suggested in this paper.

关键词: adsorption , null , null , null

INFLUENCE OF Al ON DUCTILITY IMPROVEMENT BY B IN Ni_3Al ALLOYS

YANG Wenying LU Fanxiu ZHANG Shouhua University of Science and Technology Beijing , Beijing , China Department of Materials Science and Engineering , University of Science and Technology Beijing , Beijing , 100083 , China

金属学报(英文版)

The “order-disorder” model was adopted to calculate the lattice vacancies related to the com- position change in Ni_3Al alloys.A great deal of vacancies,i.e.,the non-stoichiometric vacan- cies,may exist in the Ni_3Al alloys containing Al over stoichiometry,i.e.25 at.-%.This was confirmed by the positron annihilation technique.Therefore,the influence of Al content on the enhancing behaviour of B towards the ductility of Ni_3Al alloys can be understood by the interaction of non-stoiehiometric vacancies and B atoms.

关键词: Intermetallic compounds , null , null

Behaviour of Rare Earths in Solid Solution in Steel

LIN Qin , YE Wen , DU Yuansheng , YU Zongsen Department of Physical Chemistry , University of Science and Technology Beijing , 100083 , China.

材料科学技术（英文）

The contents of rare earth metals(REM) in solid solution in 16 Mn steel were determined by means of inductive coupling plasma (ICP) spectroscopy.The amount of REM in solid solution is only a few ppm in the steel with MnS inclusions, which rises slightly with the increasing of REM content in steel.At RE/S>1.9,the MnS inclu- sions in steel disappear completely,the REM con- tent in solid solution increases rapidly with the in- creasing of REM content.The solubility of cerium in 16 Mn steel(st 52)is less than 0.011 wt—% at room temperature. The results obtained indicate that REM in sol- id solution reduce the amount of pearlite and in- crease that of ferrite and its microhardness.Dis- solved REM oculd increase temperature of critical points,alleviate band structnre and suppress growth of austenite grains.

关键词: rare earth , null , null

Retrieving Effective Stress Spectrum of Fatigued Components from Fractographic Quantitative Analysis

WU Huaisheng ZHONG Qunpeng Jiangsu Institute of Technology , Zhenjiang , 212013 , ChinaBeijing University of Aeronautics and Astronautics , Beijing , 100083 , China

材料科学技术（英文）

Under the constant amplitude and pro- grammed loading conditions the fatigued fracture surfaces of 2024-T3 sheet are examined by SEM and TEM.A corrected method,in which the effects of loading sequence are taken into account,has been developed for the retrieval of effective stress spectrum.The parameters including d,a,C,n,R,α and σ_y are evaluated according to their influences on the retrieved results.Several computer programs have been produced for the fractographic quantita- tive analysis,and the application of image pro- cessing technique in the fractographic analysis is al- so interpreted.

关键词: fatigue , null , null , null , null

Prediction of the Occurrence of a Phase in Austenitic Matrix of Ni-base Superalloys Using Thermodynamic Equilibria Calculation

NI Kequan CHEN Guoliang ZHU Ping XIA Haiping ** Dept.of Materials Science & Engineering , University of Science and Technology Beijing , Beijing , 100083 , China*** Shenzhen Jinyuan Stainless Steel Co.Ltd. , Shenzhen.518067 , China+ To whom correspondence should be a

材料科学技术（英文）

Using the calculation of thermodynamic equilibria in multicomponent systems,two ternary phase diagrams,Ni-Cr-Mo and Ni-Cr-Co,have been calculated by optimizing the Gibbs free ener- gies with respect to phase diagrams and thermodynamic data.On the basis of this calcula- tion,the occurrence of σ-phase in the residual solid solution of commercial Ni-base superalloys, IN-713C and U-700,has been predicted.The re- sults show that the calculation of phase equilibria is successful in the prediction of the occurrence of the σ-phase.

关键词: thermodynamics , null , null , null

Quantitative Mossbauer Study on Retained Austenite and Carbide in High Speed Steel

ZHANG Henghua MA Ruzhang SU Shizhang CHANG Ruqin JIN Huijuan XU Guiqin ** Beijing University of Science and Technology , Beijing , 100083 , China*** Shanghai Iron and Steel Research Institute , Shanghai , 200940 , China+ To whom correspondence should be addressed

材料科学技术（英文）

The retained austenite in high speed steel of two different heat treatment regimes was quantitatively,determined by transmission Mssbauer spectroscopy (TMS),backscattering X-ray geometry,Mossbauer spectroscopy (BXMS) and X-ray diffraction technique.The results meas- ured by these methods were in agreement with each other.It was demonstrated that the concentration of carbides in high speed steel could be measured by transmission Mossbauer spectroscopy or Mossbau- er spectroscopy in backscattering X-ray geometry accurately.

关键词: Mssbauer spectroscopy , null , null

A New Model for Predicting Ternary Thermodynamic Properties of Solution Phase and Its Application

Zhiyu QIAO Xianran XING Shuzhen DUAN University of Science and Technology Beijing , Beijing , 100083 , ChinaChaogui ZHENG Beijing University , Beijing , 100871 , China

材料科学技术（英文）

A new geometric asymmetric model for predicting the thermodynamic properties of ternary system from three sub-binaries is presented in this paper.Its analytical expression with good calculating ac- curacy is most simple in all asymmetric models.The new model was applied to predict the enthalpies of mixing of the Bi-Ga-Sn.Au-Ag-Sn and NaCl-KCl-CaCl_2 ternary systems which were in good agreements with experimental data.Based on thermodynamic principles,the importance of the choice of asymmetric component is also discussed.The error analysis indicates that in the case of judging the asymmetric component in ternary system according to the thermodynamic criterion the deviation is minimum.It is of great significance to improve the calculating accuracy for predicting thermodynamic properties of ternary solution phase from the sub-binary ones.

关键词: thermodynamic properties , null , null