航空材料学报

Study on the strengthening phase in a ultra-high strength stainless gear steel

ZHAO Zhen-ye, LI Chun-zhi, LI Zhi, LIU Tian-qi, ZHI Min-xue, ZHU Jie-yuan, SUN Ji-guang

2003, 23(1): 1-6.

[Abstract](1422) [PDF 351KB](401)

Abstract:
The strengthening phases in a ultra-high strength stainless gear(bearing) steel have been investigated by TEM electronic micrographs and diffraction techniques.The results show that two types of hcp phases:Laves(Fe2Mo type) and M2C have been precipited in coherence with martensitic matrix during tempering and both of them may be ascribed to the existence of secondary hardening phenomenon in the steel.

Structures and properties of modified M2 cast high speed steel

FU Han-guang, XING Jian-dong

2003, 23(1): 7-10.

[Abstract](1437) [PDF 231KB](332)

Abstract:
M2 high speed steel was modified by Y-K-Na, the effects of complex modification on the structures and properties of M2 cast high speed steel has been studied The results show that the structures of M2 cast high speed steel modified by Y-K-Na were obviously refined and the eutectic carbide networks were changed into spherical After modification, the impact toughness was increased by 70.7%, wear resistance was also increased, all mechanical properties of inoculation M2 high speed steel were close to that of forging M2 high speed steel and the modified mechanism was also analyzed.

Effects of hot forming parameters on microstructure of TC6 titanium alloy

XONG Ai-ming, HUANG Wei-chao, CHEN Sheng-hui, LI Miao-quan

2003, 23(1): 11-15.

[Abstract](1448) [PDF 400KB](429)

Abstract:
Effects of deformation process parameters, including deformation temperature, strain rate and strain, on microstructure of the TC6 titanium alloy were investigated through isothermal compression and metallographic experiments The results show that deformation process parameters have significant influence on microstructure of the TC6 titanium alloy In two phases region, volume fraction of phase decreases with the increasing of temperature, but grain size increases first and then decreases with that The strain rate affects the morphologies and grain size of phase of TC6 titanium alloy The suitable strain rate makes grain size fine by accelerating the dynamic recrystallization of TC6 titanium alloy The strain has the same effect as strain rate when it overtakes the threshold.

Intracrytalline element solubility and mechanical property of a new super-high strength and toughness Al alloy cast under low frequency electromagnetic field

DONG Jie, CUI Jian-zhong, ZHAO Zhi-hao

2003, 23(1): 16-20.

[Abstract](1476) [PDF 353KB](397)

Abstract:
A new super-high strength and toughness Al alloy (10Zn-2.5Mg-2.5Cu-0.15Zr-balanceAl) was semi-continuously cast on the basis of CREM (casting, refining, electromagnetic), by lowering the electromagnetic frequency to 15～35Hz The differences of microstructure, intracrytalline element solubility and mechanical properties between DC and low frequency electromagnetic casting were investigated The effect of electromagnetic frequency and number of ampere turns on intracrytalline element solubility and mechanical properties were focused on The results show that low frequency electromagnetic cast microstructures of 10Zn-2.5Mg-2.5Cu-0.15Zr-balanceAl alloy are well refined, and intracrytalline element (Zn,Mg and Cu) solubility and mechanical properties are greatly increased It also shows that when the optimum frequency is 15～25Hz and number of ampere turns is 12800～16000A, intracrytalline element (Zn,Mg and Cu) solubility are higher, and mechanical properties are the best The billets were extruded into 12mm bars and their tensile ultimate strength are 780MPa and the elongation are greater than 8% after thermal treatment.

Process and microstructure characters of ceria nanocrystalline film on aluminium alloy LY12

JI Hong, XU Yue, ZHOU De-rui, ZHOU Yu-hong

2003, 23(1): 21-23.

[Abstract](1406) [PDF 148KB](303)

Abstract:
A ceria nanocrystalline thin film is obtained on the surface of aluminum alloy LY12 by a novel dip-coating sol-gel process with alcohol and collodion The suitable conditions of technology are established The expetiment shows that the original concentration of cerous nitrate solution and the calcine temperature influence the film quality When temperature is 400℃, the concentration of cerous nitrate solution is 30g/L,a fine film can be obtained The constituents of the film was studied by X-ray photoelectron spectroscopy (XPS), and the results indicate that the film consists of cerium and oxygen X-ray diffraction (XRD) analysis results show that cluster in the ceric thin film is 10 nanometer The influence of temperature on surface microstructure is indicated by the restults of SEM.

Internal friction peak and its damping mechanism in high damping 6013Al/ SiC_p/Gr hybrid metal matrix composite

GU Min, GU Jin-hai, SHEN Ning-fu, WANG Xi-ke, ZHANG Ying-yuan, GU Ming-yuan, LE Yong-kang

2003, 23(1): 24-28.

[Abstract](1214) [PDF 412KB](354)

Abstract:
The damping properties of the 6013Al/SiCp/Gr hybrid MMC, which was fabricated by spray atomization and deposition, were studied The results show that, the internal friction spectra of the samples exhibit internal friction peak between 150℃ to 200℃ Furthermore, the peak temperature increases with increasing frequencies When measured in the condition of increasing temperature and reducing temperature, the activation energy of the internal friction peak was calculated being 2.21eV and 1.27eV respectively by Arrhenius equation The peak temperature and peak height measured in the condition of increasing temperature decrease as compared with that in the condition of reducing temperature Through a series of analyses, it is described that the internal friction peak is of relaxation model with non-linear, and results from the dislocation movement dragging the point defect under the double action of heat and stress Its mechanism is of the dislocation-induced damping.

Research on microstructure and physical properties of recrystallized graphiteby zirconium

QIU Hai-Peng, SONG Yong-Zhong, LIU Lang, ZHAI Geng-Tai

2003, 23(1): 29-33.

[Abstract](1386) [PDF 233KB](232)

Abstract:
The recrystallized graphite was prepared from filler of calcined coke & binder of coal-tar pitch and zirconium by the hot-pressing progress in order to investigate the effects of amount of zirconium on the thermal conductivity, electrical conductivity, bending strength and microstructure of recrystallized graphite Experimental results showed that the recrystallized graphite with a amount of zirconium exhibited higher thermal conductivity, higher electrical conductivity and bending strength than the pure graphite by the same process The dopant concentration of zirconium with 6wt% might greatly decrease the electrical resistivity of recrystallized graphite, but more dopant zirconium changed electrical resistivity of recrystallized graphite a little For the high conductivity direction, the thermal conductivity of RG-Zr-12 was 410W/(m·k) Microstructural analyses revealed that the degree of graphitization of recrystallized graphite and coherence length of La increased and layers spacing of microcrystalline decreased with increasing zirconium concentration The degree of graphitization of recrystallized graphite was 97.7% and coherence length of La was 475nm when the amount of dopant zirconium was 12wt% Composition analyses indicated that zirconium added to the carbon substrate was in the form of ZrC precipitates by XRD and SEM The mechanism of the solution-precipitation using liquid solvent could be explained the catalytic mechanism of zirconium dopant servers as catalyst to accelerate the graphitization of carbon substrates.

Mechanical properties,strengthening and toughening mechanism of PF/NBR matrix montmorillonite nanocomposites

ZHAN Mao-sheng, XIAO Wei, LI Zhi

2003, 23(1): 34-43.

[Abstract](1380) [PDF 483KB](412)

Abstract:
Three kinds of montmorillonites (MMT, including S-MMT,TG-2,OLS) and one kind of short-cut glass fiber (SGF) were used to melt compounded with phenolic resin (PF), thus phenolic resin matrix composites were prepared Notch impacting and bending tests were used to study the mechanical properties and strengthening and toughening mechanism, through which some regular results were achieved Notch impact strength, bending modulus and strength of PF/NBR/SGF composites increase with the increase of the content of SGF For PF/NBR matrix montmorillonite nanocomposites, notch impact strength increase with the increase of the contents of the montmorillonites, when the content of montmorillonites reaches 5phr, the impact strength is the highest; and the bending modulus and bending strength also increase with the increases of the contents of the montomorillonites, and when the content is up to 9phr, the bending modulus and bending strength are the highest Through the comparison of the mechanical properties of the PF/NBR matrix composites, it showed that: when the content of the fillers and the experimental temperature is the same, the notch impact strength of PF/NBR/SGF composite is the highest, but the bending modulus and bending strength are the lowest; the notch impact strength of PF/NBR/OLS nanocomposites is the second one, but their bending modulus and bending strength are the highest; the notch impact strength of PF/NBR/TG-2 nanocomposities is the third one, and their bending strength and bending modulus are the second one; the notch impact strength of PF/NBR/S-MMT nanocomposities is the lowest, and the bending modulus and bending strength is the third one Secondly, for each of the PF/NBR matrix composites, when the experimental temperature is 60℃, their impact strength are the highest; when experimental temperature is higher or lower than 60℃, their impact strength lowered For PF/NBR/OLS, PF/NBR/TG-2 and PF/NBR/S-MMT nanocomposites, their mechanical properties have close relation with the space distances of montmorillonites, the greater the space distances of montmorillonites are, the better the mechanical properties world be When the content of montmorillonite is the same, the mechanical properties of the exfoliated nanocomposites are better than intercalated nanocomposite At last, montmorillonite′s toughening and strengthening mechanism was studied, and models illustrated in Fig.10 and Fig.11 are porposed.

Influence of graphite epoxy composite materials on the stress corrosion cracking of aluminum alloys

LU Feng, SUN Zhi-hua, ZHONG Qun-peng, CAO Chun-xiao

2003, 23(1): 44-48.

[Abstract](1232) [PDF 205KB](603)

Abstract:
Galvanic corrosion induced by graphite epoxy composite materials (GECM) coupled to LY12CZ and LC4CS aluminum alloys in neutral and air-saturated aqueous 3.5% NaCl solution has been investigated. The galvanic corrosion behavior was studied by continuous measurement of the galvanic current and by weight loss measurements. The slow strain rate test (SSRT) and double cantilever beam (DCB) specimens were used to evaluate the SCC of the aluminum alloys, the SSRT results showed that galvanic corrosion between GECM and LY12CZ aluminum alloy increase the LY12CZ stress corrosion crack growth rate, and reduce the crack time. In DCB stress corrosion test, the KISCC of LC4CS aluminum alloy did not change greatly in relation to the galvanic corrosion, but the date of (da/dt)Ⅱ was increased a little by GECM. The mechanism and performance responsible for SCC of aluminum alloy affected by galvanic corrosion were also discussed.

Ultrasound continuous treatment for interface of aramid fiber/epoxy composites

LIU Li, ZHANG Xiang, HUANG Yu-dong, ZHANG Zhi-qian

2003, 23(1): 49-51,62.

[Abstract](1255) [PDF 238KB](364)

Abstract:
Ultrasound was used to treat the interface of aramid fiber/epoxy composites during manufacturing composites The wettability between aramid fiber and resin is analyzed and the effects of ultrasonic action on the interfacial property and mechanical property are investigated It was observed that ultrasound can increase the interfacial and mechanical properties of composites through improving the wettability of aramid fiber and resin.

Application of PCA for quantitativing the resin and volatile content of glass-fiberreinforced phinolic resin prepreg by near infrared spectroscopy

SUN Yan-feng, HUANG Yu-dong, WANG Chao

2003, 23(1): 52-56.

[Abstract](1469) [PDF 207KB](312)

Abstract:
The near-infrared reflectance spectroscopy of glass-fiber reinforced phenolic resin prepreg has been studied The curing process of phenolic resin was investigated with Principal component analysis (PCA) method The mathematical models between near-infrared spectral parameters and quality standard of glass-fiber reinforced phenolic resin prepreg (resin content and volatile content) are built up and the effects of the analysis accuracy were investigated using the Principal component regression It was found that root mean square error of prediction for the resin content and volatile content is 0.6114 and 0.1885 respectively Above results show the feasibility of the near-infrared analytic technology for detecting quality of composite prepreg.

Research progress in high temperature wave-transparent materials

HAN Gui-fang, CHEN Zhao-feng, ZHANG Li-tong, CHENG Lai-fei, XU Yong-dong

2003, 23(1): 57-62.

[Abstract](1488) [PDF 334KB](611)

Abstract:
The characteristics of properties of the wave-transparent materials using in high-mach aircraft were reviewed The reinforced model, mechanical and electric properties of the wave-transparent materials of several systems were analyzed On this basis, the development direction of the wave-transparent materials was proposed.

2003 Vol. 23, No. 1