航空材料学报

THE AS-SOLIDIFIED MICROSTRUCTURE OF RS ELEVATED TEMPERATURE Al-Fe-Mo-Si-Zr-Ti ALLOYS

Dai Shenglong, Yu Guifu, Yan Minggao

1994, 14(2): 1-10.

[Abstract](1523) [PDF 641KB](178)

Abstract:
The as-solidified microstructure was studied using OP,SEM,TEM and X-ray diffraction.Resultsshowed that the addition of Mo does contribute significantly to the increasing of undercooling prior to so-lidification and make the mechanism of solidification transform from extraction of heat controlling processinto diffusion of solution controlling process for the 10-40μm powder particles, However for the40μmpowder particles little influence was observed due to the preferential formation of Zrrich nucleates.In order to investigate mechanism of the formation of the intercellular dispersoid which is being in debate and possibility of suppressing the dispersoid,a nucleation kinetic model which including unsteady nucleation and effect of alloy element was established.For undercooled binary Al-Fe melts,as a example,both isothermal and continuous cooling treatment methods were used to predict the hierarchy of suppression and selection of Al3Fe,Al6Fe,AlmFe,α(2wt-%),α(super saturated)phases and I-phase.A number ofimportant conclusions were drawn.

STUDY ON TiAl+Sb ALLOY

He Yuehui, Liu Yexiang, Huang Baiyun, Qu Xuanhui

1994, 14(2): 11-16.

[Abstract](1231) [PDF 333KB](164)

Abstract:
The effect of addition of Sb element on microstructure and mechanical properties of(Ti-32 wt-%Al)-Sb alloys was investigated.The test results showed that the room temperature mechanical properties couldbe improved by Sb addition,The reasons for which had been explained based on the changes in microstructure,phase structure and fracture characters with Sb addition.

EFFECT OF Nb,Mo,V CONTENTSON OXIDATION PROPERTIES OF Ti₃Al BASED ALLOYS

Sun Yufeng, Cao Chunxiao, Yan Mingao

1994, 14(2): 17-22.

[Abstract](1413) [PDF 354KB](214)

Abstract:
In this paper,effect of Nb,Mo,V contents on oxidation properties(700℃,in air)of Ti3Al based al-loys has been studied.It has been shown that the alloys would oxidize rapidly as exposed at 700℃ in theair,After oxidation exposure,about 20μm thick alloy surface layer has been found with dlssolved oxidation,in account of the poor protection of the oxide scale,An excessive addition of Nb will decrease the oxidation resistance,while dominant reduction of oxidation resistance of Ti3Al-Nb system alloy will be resulted by the addition of Mo and V.

BRAZING OF Si₃N₄ CERAMIC USING RAPIDLY SOLIDIFIED Al-BASED ACTIVE FILLER METALS

Zhai Yang, Ren Jialie, Zhuang Lijun

1994, 14(2): 23-30.

[Abstract](1438) [PDF 429KB](164)

Abstract:
In this.paper,three kinds of new rapidly solidified(RS)Al-based active filler metals have been developed.The properties of tbese filter metals have been studied.The results show that after rapid solidification,the Al-based active filler metals have finer microstructure,more homogeneous composition,lowermelting point and higher hardness. The results show that the maximum shear strength of joint with RSAl-based active filler metal at the brazing temperature of 750℃ is 208.8MPa. Brazing temperature hasmore influence on the strength of joint.When the brazing temperature exceeds a certain value,the strengthof joint decreases remarkably.The maximum shear strength of joints with Ni powders was enhanced distinctly.The maximum shear strength of joint using RS Al-based active filler metal with Ni powders is225MPa at brazing temperature of 800℃.Two Ni-rich layers formed at interface of joints with Ni powders.The main reason that shear strength of joint was enhanced was homogeneous Ni-rich layer formed atinterface of joints.

SURFACE MODIFICATION OF STEEL GCr15 BY ION IMPLANTATION

Zhou Xiying, Song Xuemeng

1994, 14(2): 31-35.

[Abstract](1312) [PDF 309KB](183)

Abstract:
Steel GCr15 used as the aeronautical bearing was implanted with B+,N+and B++N+and B++N+. The structureof implanted layer were investigated hy SEM and XRD,and hardness,wear resistance,corrossion resistance of implanted layer were also examined.The experiment results show that dispersed and amorphous phases were formed,residual austenite of surface layer was slightly decreased.Hardness,wear resistance and corrossion resistance of surface layer were obviously increased after ion implantation Finally, the mecha-nism of surface modification by ion implantation was also discussed in this paper.

EFFECT OF SDISTRIBUTION ON HOT CORROSION BEHAVIOR OF Al-Si COATING

Yang Zhonglin, Yu Xiafei

1994, 14(2): 36-40.

[Abstract](1445) [PDF 314KB](284)

Abstract:
Hot corrosion behavior of three Al-Si coatings with different forms of silicon distribution was studied by RFL test apparatus at 900℃ in an atmosphere containing 20～100ppm salt.Total time of test was 200 hours.Experimental results showed that the corrosion resistance of these coatings was closely related to the silicon distribution in coatings. When coatings are well-matched in the silicon content,silicon distribution is lower in the external zone and higher in the internal zone,it has the better hot corrosion behavior.

APPLICATION OF ODF TO ANALYSIS OF THE TEXTURE OF PURE Ti-SHEETS

He Yong, Gu Jialin

1994, 14(2): 41-44.

[Abstract](1438) [PDF 216KB](228)

Abstract:
This paper deals with ODF(Orientation distribution function)to analyze the texture types of pure Tisheets,and defines the value of ODF of the strongest texture.It shows that ODF is more superior than polefigure and inverse pole figure for analyzing the types of texture.

INGOT METAILLURGY OF ALUMINIUM-LITHIUM ALLOYS

Grushko O. E.

1994, 14(2): 45-54.

[Abstract](1497) [PDF 2716KB](157)

Abstract:
The developments and modification of ingots melting and casting methods of Al-Li alloys from Rus-sian are introduced with the emphasis on the research results of the melting feature,melt oxidation,pro-tection additions,fluxes and argon protection, nonmetallic impurities (oxygen,carbon,nitrogen,hydrogen),susceptihility to casting cracks,crystallization conditions,and ingots nonhomogeneous structure in Al-Li alloys.

APPLICATION OF THE SPRAY ATOMIZATION ANDCO-DEPOSITION TECHNIQUE TO PARTICULATE-REINFORCED MMCs

Mi Guofa, Zeng Songyan, Li Qingchun, Tian Shifan, Zhao Xianguo, Tan Jufen

1994, 14(2): 55-62.

[Abstract](1537) [PDF 475KB](123)

Abstract:
The principle and some characteristics of spray atomization and Co-deposition technique were brieflyrecommended.Take aluminium alloys as an example,the uses of this technique to the fabrication and prop-erty improvement of MMCs were summed up.

1994 Vol. 14, No. 2