航空材料学报

THE INFLUENCE OF BORON CONTENT ON MECHANICAL PROPERTIES OF Ni₃ Al SINGLE CRYSTAL

Gue Jianting, Sun Chao, Li Hui

1992, 12(1): 1-7.

[Abstract](1344) [PDF 910KB](198)

Abstract:
The relationship between Ni3Al single crystal structures with Boron contents of 0,0.52,1.37,2.22 and 3.00 at % and their mechanical properties at room and high temperatre is studied in this paper.It shows that as the Boron content grows,the tensile strength and yield strength of Ni3Al single crystal at room temperature and 800℃ increase continuously.The maximums are obtained at contents of 1.37 and 0.52at % B respectively.If the Boron content continue to grow,boride eutectic will separate out from Ni3Al structure and make its property worse.At 850℃,100MPa,rupture time and elongation of Ni3Al will obviously decrease with the increase of Boron content.But compared with Ni3Al polycrystal of the same composition,the rupture time and elongation will be one to two order of magnitude higher.

THE EFFECT OF SMALL AMOUNT OF Mg ON CREEP CRACK GROWTH BEHAVIOUR OF GH33 Ni-BASE SUPERALLOY

Zhao Congbao

1992, 12(1): 8-11.

[Abstract](1476) [PDF 268KB](165)

Abstract:
The effect of small amounts of Mg on creep crack growth behaviour of GH33 Ni-base superalloy have been investigated,at 700℃ using tensile testing plate with cracks on one side.The results show that addition of small amounts of Mg can not only notably increase the creep crack growth life but also increase creep toughness.However,It does not changed the path of creep crack growth.

THE STUDY ON THE MICROSTRUCTURES AND PROPERTIES OF ISOTHERMALLY QUENCHED 40CrMnSiMoVA STEEL

Zhong Ping, Zhang Lianrong

1992, 12(1): 12-21.

[Abstract](1346) [PDF 1794KB](191)

Abstract:
In this paper,Micostructures and mechanical properties of 40CrMnSiMoVA steel after isothermal quenching at different temperatures are studied.The results show that microstructure by isothermally quenching at 300℃ consists of bainite,martensite and retained austenite.Abnormal bainite in structure improves the combination of strength and toughness and the properties of fatigue resistance of steel,It is of great importance to increase the safety and reliability of aircraft.

A TEM INVESTIGATION ON THE MICROSTRUCTURE OF SiCp REINFORCED CAST A1 METAL MATRIX COMPOSITE

Jin Yan, Li Chunzhi, Mi Jiawei

1992, 12(1): 22-28.

[Abstract](1387) [PDF 1585KB](160)

Abstract:
The microstructure of SiCp reinforced A356 cast Al metal matrix composite(MMC)has been investigated by means of transmission electron microscopy and X-ray energy dispersion analysis,it is found that the MMC contains mainly the α-SiC,β-SiC,eutectic Si,GP Zones of Si series precipitates and a Si/Ca rich amorphous compound,The β-SiC is composed of thin slices stacking along direction.

OBSERVATION ON FINE STRUCTURE OF WORKHARDENED LAYERS AND FATIGUE CRACK PROPAGATION BEHAVIOR IN ULTRA-HIGH STRENGTH STEELS BY TEM

Zhong Bingwen

1992, 12(1): 29-36.

[Abstract](1380) [PDF 1638KB](223)

Abstract:
The fine structure change in shot peening and extrusion materials and relationship between the dislocation structure in plastic zone ahead of fatigue crack tip and the crack propagation behaviour has been investigated by means of TEM.The results show that three test conditions may cause strain-induced and phaseinduced tansformations in retained austenite and cell dislocation structure in microstructure.The cyclic stress-induced by shot peening may result in ε-carbides in lower bainite decay and may change cell dislocation structure in microstucture to subgrains.A main dislocation band with high dislocation density in the plastic zone was found.The martensite laths were crosscut by the propagation cracks.If the direction of crack propagation is inter-lath,the deviation between laths appears to be small.When cracks cross the covariant packet boundaries,the direction deviation becomes larger.

STUDIES ON MICROSTRUCTURE AND OXIDATION RESISTANCE OF THE LASER-CLAD Co-Cr-Al-Y ALLOYS

Yang Yongqiang, Zhong Minlin, Yun Huanran

1992, 12(1): 37-43.

[Abstract](1469) [PDF 794KB](275)

Abstract:
In this paper,laser cladding Co-Cr-Al-Y alloys coatings on a 1Cr18Ni9Ti substrate were obtained by a 2KW CO2 Laser with a powder feeder.The microanalysis of the coating specimens indicate that the coatings mainly consist of γ,α phases and yttrium-rich particles.After isothermally oxidized at 950℃ for 100 hs,the weight gain of the coatings is far less than that of the substrate.The improvement in oxidation resistance is believed to be partially due to the formation of the yttrium-rich oxide spikes penetrating the unoxidized specimens.

A SUMMARY ON CAD OF SUPERALLOYS

Sun Li, Gui Zhonglou, Han Yafang

1992, 12(1): 44-49.

[Abstract](1389) [PDF 384KB](174)

Abstract:
The applications for the computer-aid-design of superalloys are briefly described,the current various methods of alloy design are analyzed and divided into groups.The characteristics of the first group is mainly to adopt regressive equations,however that of the second group is mostly to derive theoretic formulae;subsquently,some examples are introduced simply;finaly,the shortages of the present design methods are pointed out,and it is put forward the development of computer-aid-design for superalloys will be toward the wide applications and the profound microphysical theories.

A QUESTION ABOUT YIELD-TO-STRENGTH RATIO OF ULTRA-HIGH STRENGTH STEEL FOR LANDING GEAR

Chen Daming, Kang Mokuang

1992, 12(1): 50-56.

[Abstract](1377) [PDF 493KB](172)

Abstract:

DEVELOPMENT OF AEROSPACE INVESTMENT CASTING TECHNIQUE

Chen Wanhua, Chen Rongzhang

1992, 12(1): 57-69.

[Abstract](1438) [PDF 1516KB](237)

Abstract:
The development of aerospace investment casting technique are reviewed.The contents include investment casting market,development of casting turbine blatdes,unidirectional solidification and single crystal technique,integral turbine rotor castings,large structure castings,titanium alloy precision castings,ceramic shell and core technology and new technique of investment casting.

1992 Vol. 12, No. 1