航空材料学报

MECHANICAL BEHAVIOR AND STRENGTHENING MECHANISM OF NiAl(Fe) MATRIX COMPOSITES FABRICATED BY REACTION COMPOCASTING

Lu Yuxiang, Tao Chunhu

1998, 18(4): 1-8.

[Abstract](1442) [PDF 262KB](248)

Abstract:
Microstructures and compressive and tensile properties,as well as strengthening mechanisms of TiC-reinforced NiAl(Fe) matrix composites fabricated by reaction compocasting have been investigated. The tensile and compressive strengthes increase with the volume fraction of the reinforcement in NiAl(Fe) matrix composites in the range of 20-1050℃. TiC/NiAl(Fe) composites exhibit higher strengthes at elevated temperatures and more satisfactory tensile elongation than the binary NiAl and its composites. The slip transfer process of dislocations is the main deformation mechanism in the NiAl(Fe) alloy at room temperature. The predominant strengthening mechanism at room temperature is believed to be related to the volume fraction of the reinforcement and the dendrite refinement resulted from the obstruction of TiC-particles. The strengthening mechanism at high temperature is due to the obstruction to grain boundary motion of TiC particles and suppression to dynamic recovery and recrystallization during deformation. The toughening mechanism of the composites is prominently attributed to the obstructive effect of plastic deformation of ductile phases during crack propagation.

DESIGN OF PARTICULATE STRENGTHENED CERAMICS 

Liu Jifu, Li Jianbao, Wang Houliang, Huang Yong

1998, 18(4): 9-12.

[Abstract](1422) [PDF 157KB](332)

Abstract:
Elastic mechanics and fracture mechanics were applied to the analysis of residual thermal stresses of particulate strengthened ceramics. The critical values of particle size and maximum volume fraction of dispersed particulates were derived and some principles in the design of microstructure and the selection of material of dispersed particulates were proposed. This formed a basis for the design of particulate strengthened ceramics.

NEW PHASE STABILITY PREDICTION METHOD OF NICKEL BASE SINGLE CRYSTAAL SUPERALLOYS

Chen Zhiqiang, Han Yafang, Zhong Zhengang, Wei Pengyi, Yan minggao

1998, 18(4): 13-18.

[Abstract](1486) [PDF 458KB](405)

Abstract:
A new phase stability prediction method,REN,for nickel base single crystal superalloys was proposed. This method was applied to predicting the phase stability of fifty nine reported nickel base single crystal superalloys in literatures. Compared with experimental data and the results predicted by Mdt method, the prediction accuracy of REM method was higher,the REM method can successfully predict TCP precipitation trend of nickel base single crystal superalloys.

INFLUENCE OF FINE GRAIN CASTING BY MOULD AGITATING ON THE STRUCTURES AND MECHNICAL PROPERTIES OF K418B INTEGRAL WHEEL

Yuan Wenming, Liu Faxin, Tang xin

1998, 18(4): 19-25.

[Abstract](1469) [PDF 305KB](264)

Abstract:
The integral wheel of K418B alloy with a fine and evenly distributed equaixed grain structure was obtained through fine grain casting by mould agitating ,which improved the distribution of primary carbide(MC) and γ′ phrase;and reduced the sizes of them.The low cycle fatigue life of fine grain cast wheel was four times that of conventional cast wheel within the temperatures of 450～650℃.

SIMULTANEOUS SINTERING AND JOINING OF CERAMIC MATERIALS BY MICROWAVE 

Bai Xiangyu, Lu Anli, Wu Su, Cai Zhipeng

1998, 18(4): 26-30.

[Abstract](1315) [PDF 188KB](239)

Abstract:
Simultaneous sintering and joining of ZTA(Al2O3+20 wt% ZrO2) and 2.7mol% yttria zirconia (Y-TZP) by microwave and conventional heating wes conducted. Densities of ZTA and Y-TZP were determined by the Archimedes method, and their joining strengthes were evaluated by performing shear tests using a thermal-mechanical simulation machine(Gleeble-1500). Microstructures were observed using scanning electron microscopy(SEM). It was found that simultaneous sintering and joining could be completed successfully by microwave. The microwave heating was characterized by more rapid and harmonious densification, finer and more uniform grain size and higher joining strength compared to the conventional method.

INVESTIGATION OF FORMING PROCESS OF Ni ZrO₂ COMPOSITE PLATING WITH HIGH HEAT RESISTANT PROPERTIES

Wang Wei, Gao Jianping, Dong Xianghong, Guo Hetong

1998, 18(4): 31-35.

[Abstract](1440) [PDF 190KB](226)

Abstract:
Ni-ZrO2 composite plating with high heat-resistant properties was prepared by co-electrodeposition technology, and the relative effect factors such as current density(i), diameter of ZrO2 particles(d), stirring methods(m), ZrO2 content in the solution(c) and also their interactions was investigated systematically with an orthogonal design. The arrangement orders of the factors affecting the ZrO2 content in composite plating are as follows:d>m>d?m>c>d?c>i?m.

COATING SILICON CARBIDE ON CARBON FIBRES BY PVD

Hua Wenjun, Chen Daming, Li Bintai, Zhang Jiansu

1998, 18(4): 36-39.

[Abstract](1434) [PDF 208KB](334)

Abstract:
The technology of SiC-coating on carbon fibres by PVD was investigated and the effect of processing parameters on thickness and properties of of coating fiber wes also studied. Uniform and continuous coating on carbon fibres was obtained by using the optimized processing parameters. The mechanical properties of carbon fibres were not decreased if moderate coating thickness was chosen. The low temperature and high speed of deposition are characteristic of this technology.

STUDY ON DRAWING SUS304 STAINLESS STEEL WITH REACTION BONDED Si₃N₄ CERAMICS DIE

Liang Jinsheng, Liang Guangchuan, Zhang Jianjun, Gao Xinghua, Fu Deshui

1998, 18(4): 40-44.

[Abstract](1397) [PDF 175KB](439)

Abstract:
The drawing tests of stainless steel (SUS304) with reaction bonded Si3N4 ceramics die lubricated with water base lubricant were carried out using a four columns YA 100 type drawing machine.The reaction bonded Si3N4 ceramics die matched with water base drawing lubricator in drawing stainless steel doesn’t produce abrasive defects either on the surface of drawn parts or the die.This is a new potential material which can replace metal dies in the future.

INFLUENCE OF STRESS CONCENTRATION ON CREEP-FATIGUE BEHAVIOUR OF A HIGH TEMPERATURE ALLOY

Shi Huiji, He Yuhuai, Liu Shaolun, Han Zengxiang

1998, 18(4): 45-51.

[Abstract](1441) [PDF 462KB](306)

Abstract:
A series of low cycle fatigue and creep-fatigue tests were performed with a sueralloy on smooth and notched specimens.The cyclic stress-strain behaviors and fracture characteristics of the notched specimens were emphatically investigated. A comparison of fatigue behavior between smooth and notched specimens was made and lifetime of notched specimens was evaluated. At the same temperature, the fatigue-creep lives of the smooth specimens are far greater than that of the notched specimens.

CHALLENGE AND DEVELOPEMENT TRENDS TO FUTURE AERO ENGINE MATERIALS

Fu Hengzhi

1998, 18(4): 52-61.

[Abstract](7450) [PDF 445KB](2437)

Abstract:
The development of next generation aero-engines requires support of advanced materials and appropriate new structures and technologies. According to the service environment of aero-materials,some points of view on combining the structure concept with material concept,the advancement and reliability of aero-engines with the controllability and safety of structure and defect for research and development of materials are proposed. From the aspects of fundamental properties of maximam service temperature,high temperature specific strength,antioxidation,toughness,conductivity and processing ability,the behaviour of traditional and new materials systems is analysed and some suggesstions aimed at the problems in development of aero-engine materials in China are presented.

1998 Vol. 18, No. 4