航空材料学报

Microstructure evolution of Cu-Mn alloy under laser ultra-high temperature gradient and rapid solidification condition

YANG Sen, ZHONG Min-lin, ZHANG Qing-mao, HUANG Wei-dong, LIU Wen-jin, ZHOU Yao-he

2001, 21(2): 1-5,13.

[Abstract](1421) [PDF 960KB](260)

Abstract:
Laser rapid solidification experiments have been performed on Cu-26.6wt%Mn,Cu-27.3wt%Mn and Cu-31.4wt%Mn alloys to investigate their microstructures evolution with growth rate under ultra-high temperature gradient, respectively. The experimental results showed that the microstructure of Cu-26.6wt%Mn alloy changed from cellular to dendrite, super-fine cellular and segregation-free solid with the increase of growth rate; no dendrite growth appeared in the whole growth rate range for Cu-27.3 wt%Mn and Cu-31.4wt%Mn alloy, whereas fully grew in the form of cellular. The critical rates of absolute stability for Cu-31.4 wt%Mn,Cu-27.3wt%Mn and Cu-26.6wt%Mn alloys were 113.3, 212.6 and 260.5mm/s, respectively, which is reasonable agreement with that of the predicted by M-S theory.

Effect of zirconium on the recrystallization, anisotropy and texture in Al-Li alloys

YANG Shou-jie, DAI Sheng-long, LU Zheng, SU Bin, YAN Ming-gao

2001, 21(2): 6-9.

[Abstract](1506) [PDF 219KB](334)

Abstract:
The recrystallization, anisotropy and texture of Al-Li(-Zr) alloys were studied. The element Zr can retard the recrystallization processing and refine grains. It can be concluded that the mechanical properties anisotropy of Al-Li(-Zr) alloys is affected not only by crystalline textures but also by other aspects such as characteristics of the second phase particles in the matrix.

The micro-deformation behaviors of containing rare earth high-strength Al-Li alloy

ZHAO Zhi-long, LIU Lin, CHEN Zheng

2001, 21(2): 10-13.

[Abstract](1499) [PDF 1023KB](211)

Abstract:
Based on the tensile performance of aluminium-lithium alloys 2090 and rare earth high strength aluminium-lithium alloy (2090+Ce, add trace addition of cerium to the alloy 2090), the dislocation microstructures in the tensile samples of two alloys were investigated by means of TEM technique in order to understand the relationship between macro properties and micro deformation. The observations show that there still obviously exists characteristics of co-planar slippage in the alloy 2090+Ce, however its slipping strip is relatively dense and uniform by comparison with common industrials aluminium-lithium alloy 2090. The rather stronger strain contrasts has been found in the vicinity of some big angle grain boundary in the alloy 2090+Ce by weak beam dark field image, which manifested that the tendencies of local strain in this alloy is relatively stronger.

A study of homogenization processes for a new type ultra-high strength aluminum alloy

LU Zheng, YANG Shou-jie, JIANG Hai-feng, LU Jian, DAI Sheng-long

2001, 21(2): 14-17.

[Abstract](1392) [PDF 707KB](663)

Abstract:
In order to improve the properties of the ultra-high strength aluminum alloy, some variable homogenization processes were studied. It is found that the two stage homogenizations are better than those of one stage. The properties are improved through the plateau of 400℃, which is explained that it can accelerate the precipitation of Al 3Zr which finning the sub grains. The excellent homogenization process have been determined:400℃/4h+463℃/24h.

Investigation of material factors on fretting fatigue behavior

LIU Dao-xin, LIU Yuan-yong, LI Dong-zi, HE Jia-wen

2001, 21(2): 18-21,29.

[Abstract](1536) [PDF 257KB](281)

Abstract:
The fretting fatigue resistance (FFR) of materials is related to composition, microstructure, and mechanical properties of the materials. The relationship is different for different materials. In order to further investigate the influence of material factors on FFR, the FFR of two heat-resistant steels with different tension strength and two titanium alloys with different microstructure was compared. Fretting pad material on FFR was also studied in the present paper. The results show that the FFR of Ti6Al4V and Cr17Ni2 with high tension and plain fatigue strength is higher than that of Ti5Al2.5Sn and 1Cr11Ni2W2MoV respectively. Which means that FFR is predominantly determined by tension and plain fatigue strength for the materials having same or similar microstructure. In the situation of using a hard fretting fad, fretting fatigue crack initiates easily and the fretting fatigue life is low. Under this condition, shot peening is remarkable effective for improving FFR of materials.

Orientation dependence of low cycle fatigue life of single crystal nickel-base superalloy DD6 under high temperature

LI Ying, SU Bin, WU Xue-ren

2001, 21(2): 22-25.

[Abstract](1466) [PDF 1084KB](292)

Abstract:
The low cycle fatigue properties of a single-crystal nickel-base superalloy, DD6, have been examined at 760℃ and 980℃ in air. Specimens having crystallographic orientation near, and were tested under fully reversed strain. It is found that fatigue life as a function of total strain range was highly orientation dependent at both 760℃ and 980℃, but the influence of orientation vanished to a great extent when stress amplitude was introduced.

Effect of microstructure shape on damping property of ZA27Ce alloy

LIU Yao-wen, CHEN Quan-de, HAN Shun-chang

2001, 21(2): 26-29.

[Abstract](1402) [PDF 904KB](184)

Abstract:
After solid solution to as-cast ZA27Ce alloy,artificial aging at 96℃, 180℃, 250℃ were applied to respectively. Q-1 (damping capacity ) were measured as the damping properties with suspending flexural resonance method,the results showed us that the damping property after artificial aging at 96℃was better than that at 180℃ and 250℃. Consequently microstructures were studied by the use of SEM, the results were that spheroidized structures were obtained by the artificial aging at 96℃, lamellar structures were obtained at 180℃and 250℃.In the end of the article, damping property of the spheroidized structure was thought to be better than that of the lamellar structure with the help of energy dissipation mechanism of the interfaces sliding of equiaxed crystals.

Investigation on the pseudo eutectic structure formed by solid diffusion of Zn powder and Al powder

HAN Bin, LI Shi-chun, HU Xiu-lian

2001, 21(2): 30-33.

[Abstract](1452) [PDF 552KB](286)

Abstract:
The specimens have been prepared by cold compression and hot compression respectively. The effects of preparation technologies on the microstructure and the interface function have been investigated with OM, SEM, TEM and X-ray diffraction. The quasi eutectic structures are found in hot compression specimens and the quasi-eutectic structure in the specimen of Zn-5Al is finer than the lamellar structure in Zn-5Al eutectic alloy. The diffusion of atoms along grain boundary and interface plays an important role in the process of formation of quasi eutectic structure.

The influence of aluminum contents on the microstructures and electrical properties of CuNi resistive films

DONG Xian-ping, WU Jian-sheng

2001, 21(2): 34-38.

[Abstract](1441) [PDF 243KB](363)

Abstract:
CuNi resistive films with different aluminum contents (0wt%, 10wt%, 20wt%, 30wt%) were fabricated by magnetron sputtering. Crystallization behavior of the films was analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD), while the surface structure was studied by X-ray photoelectron spectroscopy (XPS). The results showed that, the island crystallization phases CuNi existed in the sputtered CuNi films without aluminum. When aluminum contents raised a certain amount, the chain distributed fine (Cu,Ni)9Al4 phases and the continuous (Cu,Ni)Al phases were formed in the CuNi films respectively. The lattice structure of crystallization phase in the annealed films was similar to that in the sputtered films. After annealing in air, the porous copper oxides were formed on the undoped films surface, while the dense aluminum oxides were formed on the films surface which contained more than 10wt% aluminum. Adding aluminum to CuNi films could decrease the resistivity. There was a minimum TCR for an aluminum contents of 10wt%～20wt%. The increase of annealing temperature decreased the resistivity and raised the TCR of the CuNi films which had been added with aluminum, while that enhanced the resistivity and made the variation of TCR irregular for the films without aluminum.

TEM study on the microstructure of continuous SiC fiber reinforced aluminum composites

YANG Sheng-liang, ZHUO Yue, WAN Hong, YANG De-ming

2001, 21(2): 39-43.

[Abstract](1403) [PDF 713KB](232)

Abstract:
The interfacial microstructures of several kinds of continuous SiC fiber reinforced aluminum composites fabricated by different method including composite wires prepared by ultrasonic liquid infiltration method, composite plates made by hot press process and by vacuum liquid infiltration method have been investigated by means of transmission electron microscope (TEM). The results show that there aren’t obvious interface reaction products for samples of as received and thermal exposed at 550℃×1h. However, a reaction zone with a thickness about 100～200nm observed while the samples exposed at 650℃×1h. This study indicates that the SiC/Al composites possess a good interfacial chemical stability for the adopted fabricating process.

Study on mechanical properties and processing parameters of continuous fiber reinforced thermoplastic composites

WANG Rong-guo, LIU Wen-bo, ZHANG Dong-xing, ZHANG Hong-tao, HUANG Long-nan

2001, 21(2): 44-47.

[Abstract](1479) [PDF 589KB](834)

Abstract:
Three kinds of thermoplastic composites have been made with PES, PES C, PEK C and a high stress continuous glass fiber roving. The preimpregnating technology, forming process parameters were investigated. Test on their elementary mechanical properties, and the fracture appearance (SEM) of 45° longitudinal transverse shear were analysed.

Development study of airplane hang module radome

DI Xi-yan, LIANG Guo-zheng, MA Xiao-yan

2001, 21(2): 48-50.

[Abstract](1467) [PDF 479KB](270)

Abstract:
With the 4503A BMI resin applied in RTM process was modified,a new modified BMI resin was obtained for making radome. Not only the dielectric properties of the original resin were kept up, but also it was satisfied to hand lay-up moulding. In the paper, the airplane hang module radome was developed with this resin, the dielectric performance were achieved, its shaping process and mold design was introduced.

Study on shear fatigue and creep properties of two moderate temperature curing adhesives

QIAO Hai-tao, LAI Shi-hong, ZOU Xian-wu, YANG Feng-qin

2001, 21(2): 51-54.

[Abstract](1559) [PDF 170KB](312)

Abstract:
Shear fatigue and creep properties of SY-24B film adhesive and SY-H2 paste adhesive have been studied.SY-24B film adhesive and SY-H2 paste adhesive are all moderate temperature curing adhesives.SY-24B film adhesive is toughened by rubber and SY-H2 paste adhesive is toughened by thermoplastic resin.SY-24B film adhesive has better toughness than SY-H2 paste adhesive,but the latter has better shear fatigue and creep properties.Difference of the two adhesives is relevant with flexibilizer and bondline thickness.Temperature,stress and time are also factors influencing the creep residue deformation.

The estimating method of atmospheric aging age on polymer matrix composites

ZHAO Yan, LIANG Zhao-hu

2001, 21(2): 55-58.

[Abstract](1471) [PDF 1335KB](451)

Abstract:
An equation on atmospheric aging age with high confidence and reliability have been founded by studying and analysing a lot of atmospheric aging data about polymer matrix composites. Then the atmospheric aging age and aging residual strength with high confidence and reliability, which is badly in need of providing in engineering design can be calculated. Meanwhile a litter sample method that can define parameters in this aging equation has been advanced. This method can save above 50 percent specimen comparing with the traditional testing method in group under the same precision and it can improve precision on estimating greatly with the same amount of specimens. Finally a verifying example has been given.

The development of reticulated polyurethane foam

TIAN Hong, Wu, Qiong, JIANG Ping, GAO Yong-ting

2001, 21(2): 59-63.

[Abstract](1449) [PDF 793KB](462)

Abstract:
The paper describes the initial development, evolution, and use of reticulated polyurethane foam as an explosion suppression material in fuel tanks and dry bays. The material is a lightweight flexible foam composed of a skeletal matrix of tiny interconnecting strands which act as a three-dimensional fire screen. Reticulated polyurethane foam used as an explosion suppressor is a combat proven system refined from experience that will minimize fuel tank overpressure that caused by: gunfire; electrical ignition; lightning strikes; and electrostatic discharges. It functions as a multiple hit, passive defense system to reduce vulnerability and increase survivability.

2001 Vol. 21, No. 2