航空材料学报

Study on heat treatment of DZ40M directionally solidified cobalt base superalloy

JIANG Wen-hui, GUAN Heng-rong, HU Zhuang-qi

2001, 21(1): 1-5.

[Abstract](1415) [PDF 1101KB](318)

Abstract:
DZ40M alloy is a newly developed directionally solidified cobalt-base superalloy. The present work investigated the effect of heat treatment on microstructures and mechanical properties of DZ40M alloy.The results showed that solution treatment at 1280℃ for 4h could dissolve the primary carbides M7C3 and MC essentially and the alloy became a single phase solid solution. Aging treatments at both 950℃ and 1050℃ could harden the alloy and 950℃ aging caused a more effective hardening.Two peak aging treatments were determined as 950℃/12h and 1050℃/24h.Aging treatments resulted in secondary M23C6 precipitation.950℃/12h treatment increased room-temperature strength and stress-rupture life at high temperature substantially and reduced ductility.However,in spite of it,the alloy still has adequate ductility.Although it increased room-temperature mechanical properties,1050℃/24h treatment deteriorated stress-rupture properties at high temperature.

Study on the burning behavior of Ti-Cr binary alloys and their burning products

ZHAO Yong-qing, ZHOU Lian, DENG Ju

2001, 21(1): 6-9.

[Abstract](1421) [PDF 244KB](208)

Abstract:
The burning behavior of Ti-Cr binary alloys and their burning products are studied by means of direct current simulation burning(DCSB) ignition method. The results indicate that the burning velocity of Ti(10%)Cr alloys is low. If the alloying element Cr content is greater than 15% the burning speed is lower. Burning product surface cracks and their oxide scales are porous. The interface between burning products and matrix is also porous for Ti-(10%)Cr alloys, which can not retard oxygen diffusion into the matrix. While the interface of Ti-(10)Cr alloys is tenacious, which can retard oxygen diffusion into the matrix and decrease the burning velocity. The products of Ti-Cr alloys are TiO2, TiO and TiCrO3, and the reasons for TiCrO3 formation are analyzed.

Hot deformation behavior of Ti-6Al-2Zr 1Mo-1V alloy

HONG Quan, ZHANG Zhen-qi

2001, 21(1): 10-12.

[Abstract](1512) [PDF 631KB](464)

Abstract:
Hot compressive deformation test of Ti-6Al-2Zr-1Mo-1V titanium alloy were studied by Gleeble-1500 Formaster Press Simulator at constant temperatures and constant strain rates. The ranges of temperature and strain rates were 700～1000℃ and 5×10-3-s-1～50s1. The compressive true stress vs true strain curves have been measured and the hot deformation microstructures were observed. The results showed that the softening mechanism was dominated by dynamic recrystallization and dynamic recovery at different condition. The sensitivity exponent of strain rate was increased with raising of deformation temperature.

Nextel 720/silica composites by metal organic chemical vapor infiltration

CHEN Zhao-feng, ZAHNG Li-tong, CHENG Lai-fei, XU Yong-dong, XIAO Peng

2001, 21(1): 13-17.

[Abstract](1367) [PDF 217KB](223)

Abstract:
The development of non-oxide ceramic matrix composite has resulted in composites with suitable property for certain structural application, but they all retain susceptible to long term degradation after high temperature exposure to oxidizing environments. Continuous oxide fibers reinforced oxide matrix composites are attractive for use as high temperature structural materials because they can combine composite properties with long-term oxidative stability. In this paper, the processing of Nextel 720/silica composites by MOCVI (metal organic chemical vapor infiltration) at atmosphere pressure is described. TEOS (Tetraethylorthosilicate) was used as precursor. The effects of concentration of O2, flux of carrier,temperature of TEOS and deposition temperature on deposition rate of silica and Nextel 720/silica microstructure were studied with lots of experiments. The results exhibit the optimal conditions for MOCVI are TEOS temperature 60℃, deposition temperature 600℃, flow rates of Ar and O2 400 ml·min-1 and 30 ml·min-1 respectively.

TLP diffusion bonding of Si₃N₄ ceramics using Ti/Ni/Ti multilayer and controlling of joints′ quality

ZOU Gui-sheng, WU Ai-ping, REN Jia-lie, LI Sheng, REN Wei-jia

2001, 21(1): 18-22.

[Abstract](1483) [PDF 222KB](246)

Abstract:
TLP diffusion bonding of Si3N4 ceramics with Ti/Ni/Ti multilayer was investigated.The existing time of Ni-Ti transient liquid phase is short, and the strength of the interface formed within this duration is very low.The formation of strong joints needs further solid-state diffusion reaction, and its microstructures is Si3N4/TiN/Ti5Si3+Ti5Si4+Ni3Si/NiTi/Ni3Ti/Ni. The joints′ strength is affected by bonding parameters, which include bonding time、bonding temperature、bonding presssure、thickness of Ti or Ni. The shear strength of joints at room temperature and 800℃ could reaches 142MPa and 61MPa, respectively.

Microstructure and mechanical properties of spray-deposited Al-Si-Fe-Mn-Cu-Mg alloys

WANG Feng, HE Jian-ping, YANG Bin, CUI Hua, DUAN Xian-jin, XIONG Bai-qing, ZHANG Ji-shan

2001, 21(1): 23-26.

[Abstract](1506) [PDF 491KB](337)

Abstract:
In this study, Al-20Si-5Fe-(0～3)Mn-3Cu-1Mg alloys were synthesized by spray atomization and deposition technique. The microstructures and mechanical properties of spray deposited hypereutectic Al-Si alloys were studied using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and tensile tests. The effect of Mn content on the microstructural evolution of the high-silicon aluminum alloy has been examined. The result indicates that with the addition of 3% Mn to Al-20Si-5Fe-3Cu-1Mg alloy, the needle shape of Al-Si-Fe intermetallics is substituted by the particle shape of Al15(FeMn)3Si2 phases. Furthermore, spray-deposited Al-20Si-5Fe-3Cu-1Mg alloy has greater strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.

Effect of different temperature and strain rates on thin plate aluminum alloy LY12CZ

XU Fei, LIU Bin, LIU Yuan-yong

2001, 21(1): 27-31.

[Abstract](1379) [PDF 994KB](211)

Abstract:
In this paper, the effects of three kinds of temperature and two kinds of strain rates on the LY12CZ plate are studied. From the experimental study and the numerical analysis, four conclusions can be made. Firstly, the method to determine the stable crack growth in experiment is workable. Secondly, the initiation fracture toughness is unchanged under different temperature, while for the crack propagating process, the fracture toughness decrease as the environment temperature increase. Thirdly, the dynamic initiation fracture toughness is 40% lower than that of the quasi-static condition. Fourthly, by comparing with the incremental path-independent integral, the dynamic J integral can be used widely.

Study on Ti/ZrO₂ interface reaction

LI Bang-sheng, SHANG Jun-ling, GUO Zhen-sheng

2001, 21(1): 32-35.

[Abstract](1501) [PDF 186KB](485)

Abstract:
By means of DSC and SEM, the interface reaction process and the initial reaction temperature between Ti and ZrO2 in the Ti-ZrO2, the Ti-Al-ZrO2 and the Ti-B-Al-ZrO2 system have been studies, respectively. The result is that the initial reaction temperatures between Ti and ZrO2 increase gradually with the addition of the Al, B and the microcontent additive. Compared to the Ti-ZrO2 system, the initial reaction temperatures in the Ti-Al-ZrO2 system and the Ti-B-Al-ZrO2 system increase by 50℃ and 70℃, and the interface reaction between Ti and ZrO2 mold material is weakened.

Micromechanics model of the thermo-residual stress for fiber reinfoced aluminum matrix composites

NIU Li-Sha, HU Qi-Yang, SHI Hui-Ji

2001, 21(1): 36-42.

[Abstract](1461) [PDF 1772KB](204)

Abstract:
In view of the different parts of composition, a three-layer micromechanical model of matrix/coat/fiber is established. It can be used to analyze the stress-strain relationship of fiber-reinforced metal matrix composites with coating material under a superposition of thermal and mechanical loads. In this paper the model is applied to calculate the thermo-residual stress in production of a fiber-reinforced aluminum matrix composite. The physic behavior of the coating material plays an important role in the total mechanical characteristics. Some components of the residual stress in the coat is much greater than that in the matrix and fiber. The transversal stress is obviously influenced by varying the axial modulus of elasticity of the coating material.

Curing kinetics of a liquid crystalline epoxy with the aromatic ester mesogen by FTIR

CHEN Li-xin, WANG Ru-min, LAN Li-wen, LIAO Jian-wei, XU Ya-hong

2001, 21(1): 43-46.

[Abstract](1407) [PDF 898KB](237)

Abstract:
The curing processes of diglycidlether of 4-hydroxyphenyl-4-hydroxybenzoate(PHBHQ) with four different amine curing agents were studied by means of the DTA. A suitable curing agent,4,4’—diaminodiphenyl methane(DDM)was selected as well. Based on the self-catalyzed curing model of epoxy resin and equal activity of hydrogen amino, the isothermal curing processes of PHBHQ/ DDM liquid system at 90℃,120℃,140℃ were monitored by Fourier Transform Infra-Red Spectrum(FTIR). The result showed that the curing process was accorded with the self-catalyzed curing model when the reaction extent bellowed 40%.

Study of circular impact damage to kevlar composites and mechanism

WEI Bo-rong, JIANG Hai-bin, LI Ming-qi

2001, 21(1): 47-50.

[Abstract](1478) [PDF 536KB](287)

Abstract:
Thin Kevlar composites have been impacted by circular cone (cone angle: 60°)in 2～8m/s impact speed. The damnification process and appearance-and its mechanism-have been investigated. The result showed that damnification size of Kevlar composites was larger than glass fiber composites. The anti-penetrate capability of composites increases when the impact speed increases. Distinct function of crack inducement occurs when circular cone penetrate composites increases. The circular cone impact energy absorption for composites is decided by destroy model.

Method on measuring fibre permeabilities in resin transfer molding

LI Hai-chen, ZHANG Ming-fu, WANG Biao

2001, 21(1): 51-54.

[Abstract](9087) [PDF 964KB](346)

Abstract:
This paper introduces the processes and characterizations of the resin transfer molding briefly. The governing equations of resin flow are presented on the base of Darcy′s law. By the transformation of the anisotropic system and its equivalent isotropic system, a novel method is proposed for measuring the in-plane permeabilities of the anisotropic fibre preform. The in-plane permeabilities of the orthotropic fabric media are calculated from fluid and fibre properties together with data from the mold filling experiment, and good agreement is found between the results and the quoted datas.

High-temperature polyimide composites and its application in aeronautical engine

TAN Bi-en, YI Xiao-su

2001, 21(1): 55-62.

[Abstract](4798) [PDF 1606KB](1027)

Abstract:
This paper reviewed the progress of high-temperature PMR type polyimide matrix composites, and summarized its application in aeronautical engine field.

2001 Vol. 21, No. 1