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Search Results: 1 - 10 of 465456 matches for " China To whom correspondence should be a "
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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 Deptof Materials Science & Engineering,University of Science,Technology Beijing,Beijing,China Shenzhen Jinyuan Stainless Steel CoLtd,Shenzhen,China To whom correspondence should be a,

材料科学技术学报 , 1992,
Abstract: Using the calculation of thermodynamicequilibria in multicomponent systems,two ternaryphase diagrams,Ni-Cr-Mo and Ni-Cr-Co,havebeen calculated by optimizing the Gibbs free ener-gies with respect to phase diagrams andthermodynamic data.On the basis of this calcula-tion,the occurrence of σ-phase in the residual solidsolution of commercial Ni-base superalloys,IN-713C and U-700,has been predicted.The re-sults show that the calculation of phase equilibria issuccessful in the prediction of the occurrence of theσ-phase.
On Grain Size Dependence of Minimum Creep Rate
LI Pei''en Institute of Materials Science,Engineering,Shanghai Jiaotong University,Shanghai,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Abstract: The available experimental results have been summarized concerning the effect of grain size on minimum creep rate.There are two types of creep rate-grain size relations.One is that there is a criti- cal grain size above which creep rate is independent of grain size,below which creep rate increases with the decrease of grain size.The other is that there is an intermediate grain size at which creep resistance is optimum.The first relation usually occurs at higher temperatures(>0.5 T_m),and intermediate stress ranges,while the second relation at interme- diate temperature ranges(0.4-0.5 T_m)and higher stresses.For the two types of creep rate-grain size relations,the increase of the creep rates with the de- crease of grain size for small grain sizes is all due to grain boundary sliding.For large grain sizes,a dis- location climb mechanism is dominant in creep deformation for the first relation,while a Hall-Perch grain boundary strengthening effect is believed to play an important role by dislocation glide mechanism for the second relation.
Influence of Ca/S and Rolling Reduction on Shape of Sulphide in Free-cutting Steel 5NiSCa
JIANG Laizhu CUI Kun Huazhong University of Science,Technology,Wuhan,China To whom correspondence should be addressed,

材料科学技术学报 , 1990,
Abstract: 1.IntroductionThe shape of sulphide has a great influ-ence on machinability and transverse prop-erty of steel.It is very important to obtainoval sulphide instead of elongated one forimproving machinability and transverseproperties1,2].
Influence of Carbon Content and Solidification Condition on Incipient Melting of DS Superalloy MAR-M200+2Hf
ZHENG Yunrong,WANG Luobao,LI Chenggong Institute of Aeronautical Naterials,Beijing,China To whom correspondence should be addressed,

材料科学技术学报 , 1989,
Abstract: Hf lowers the incipient melting temperatureof superalloy. As carbon content in Hf-bearingalloy decreases, the incipient melting temperaturedrops furthey. PD ingots have stronger tendencyto incipient melting than HRS ones. Even thoughin PD ingot, the sensitivities at both endsof the ingot are quite different. The meltingof Ni_5Hf phase may be considered as one of themain factors affecting incipient melting. Themore Ni_5Hf the alloy contains, the more seriousthe incipient melting becomes. The results ofdifferential thermal analysis (DTA) have provedthat the peak of 1135-1160℃ corresponds tothe melting range or Ni_5Hf. By means of apretreatment at 1150℃, 8h, Ni_5Hf phase can beeliminated in two ways: the reactionNi_5Hf+γ(C)→MC_(2)+γ and solid solution, andtherefore the final solid solution treatmentcan be carried out at 1260℃. This brings abouta high homogenized structure and further increasesthe stress rupture properties of the alloy at1040℃, 140 MPa.
Kinetics of Oxidative Dearsenication of Niccolite Ore with Microwave Radiation
TAO Dongping LIU Chunpeng Deptof Metallurgy,Kunming Institute of Technology,Kunming,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Abstract: The rate processes of oxidative dearsenicationof niccolite ore in microwave oven and inconventional furnace were measured withthermogravimetric technique.The results show thatthe dearsenication rate of niccolite ore withmicrowave heating becomes faster than that withconventional heating.Under the conditions of an approximate linearheating and a definite air flow,the oxidativedearsenication process of niccolite ore is mainlycontrolled by interfacial chemical reaction.The ex-perimental data are in agreement with
DirectionaHy Solidified High-strength Superalloy DZ22
CHEN Rongzhang WANG Luobao WANG Yuping Institute of Aeronautical Materials,Beijing,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Abstract: Alloy DZ22 possesses rather high intermediate and elevated temperature mechanical properties comparable with the advanced commercial DS al- loy PWA1422.The alloy composition is based on PWA1422 alloy,only the content ranges of Hf,C and Zr are changed for systematic study.The pres- ent melting technology for master alloy ingot and DS process parameters for components are suitable for this alloy.The alloy revert which has been specially processed can be reused.The mould with- drawal rate during directional solidification affects the crystal orientation,alloy structure and the me- chanical properties of DS castings.The increment of solution-treatment temperature increases obvi- ously the longitudinal stress-rupture life at high temperature but decreases transversal one at inter- mediate temperature.The production practice in batches has demonstrated that alloy DZ22 has not only high mechanical properties but also excellent processing performance,including castability, weldability and machinability.It is indeed a favorable material for advanced aero and land gas turbine engine blades with complex inner cooling passage.
A Statistical Model of Quantitative Relationship between Striation Spacings and Fatigue Crack Growth Rates
YANG Jingjun,KE Wei Institute of Corrosion,Protection of Metals,Academia Sinica,Shenyang,China To whom correspondence should be addressed,

材料科学技术学报 , 1989,
Abstract: Fatigue crack growth experiments were per- formed on A1 alloy LD 10 and Ti-6A1-4V alloy. Fatigue striation spacings and the deviation angles between the direction of micro-crack growth and that of macro-crack growth were quanti- tatively measured on fracture surface using scanning electron microscope. A statistical model of the relationship between striation spacings and fatigue crack propagation rates was developed on the basis of a statistical analysis of the deviation angles, Good agreement between experimental results and theoretical results calculated with the present model was obtained.
Molecular Dynamics Simulation of Liquid Noble Metals Au and Ag
LI Qingchun CHEN Kuiying Deptof Metals,Technology,Harbin Institute of Technology,Harbin,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Fatigue Crack Propagation in Plain Carbon Dual-phase Steel
LEI Tingquan LIN Guangyong Deptof Metals,Technology,Harbin Institute of Technology,Harbin,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Abstract: The effect of volume fraction V_M and carboncontent(%C)_M of martensite was studied on the fa-tigue crack propagation behaviour of plain carbonmartensite plus ferrite M+F dual-phase steel.Theexperimental results show that the △K_(th)decreasesand da/dn increases with increasing V_M and(%C)_M at a load ratio R=0.05.High△K_(th)valuesare obtained by obvious crack closing ability causedby high roughness of the fractured surfaces.
Stability of Phases in SiC and Si_3N_4 Whisker Formation
CHEN Shengqi ZHOU Yanchun XIA Fei Institute of Metal Research,Academia Sinica,Shenyang,China To whom correspondence should be addressed,

材料科学技术学报 , 1992,
Abstract: The stability of the phases in equilibrium is calculated and discussed in order to analyse and predict the reactions in SiC and Si_3N_4 whisker formation.Equilibria among SiC,Si_3N_4,Si_2N_2O,SiO_2 and the gas phase are evaluated at different C activity,N_2 pressure,and temperature.According to the phase stability diagrams,Si_3N_4 whisker was formed with the increase of N_2 pressure and decrease of C activity;SiC whisker was stable with the increase of C activity and decrease of N_2 pressure.In order to control the impure phases during the whisker formation,O_2 partial pressure is the most important factor.
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