航空材料学报

Isothermal Solidification Process of TLP Diffusion Bonding for DD3 Superalloy

LI Xiao-hong, YE Lei, ZHONG Qun-peng, CAO Chun-xiao, XIONG Hua-ping

2011, 31(6): 1-6.

[Abstract](3412) [PDF 9766KB](966)

Abstract:
The TLP bonding process for DD3 superalloy using a B-contain interlayer alloy with different temperature and holdingtime is analyzed. Microstructures of different joints were observed and the widths of the eutectic zone of the centre of the joints were measured. It shows that the width is inversely proportional to the square root of holding time. Based on the result, the time for isothermalsolidification at 1150℃, 1200℃ and 1250℃ are not more than 3h, 2h and 1h respectively by the estimation. By establishing the diffusion model and using the error function solution to the second Ficks law,the time for isothermalsolidification at different temperature is calculated by NiB phasediagram and DD3B analogous phasediagram,respectively.The calculated results show that for a certain bonding system, there exists an optimum temperature at which the time for isothermal solidification is the shortest. According to the experimental results, it is suitabk to choose 1250℃ as the bonding tamperatune for DD3 superalloy.

Effects of Cu on Microstructure and Mechanical Properties of Fe3Al10%Ni Bulk Nanocrystalline Prepared by Aluminothermic Reaction

LA Pei-qing, LIU Xue-mei, LIU Hui, LU Xu-efeng, WEI Yu-peng, BAI Ya-ping, CHEN Jing-min

2011, 31(6): 7-11.

[Abstract](1601) [PDF 12633KB](652)

Abstract:
Effects of Cu additions on microstructure and mechanical properties of Fe3Al-10%Ni bulk nanocrystalline prepared by aluminothermic reaction were studied. The microstructure was studied by OM，EPMA，XRD and TEM, and the hardness and compressive strength were measured. The results reveal that the low Cu content (2%) maintained the bcc crystal structure and resulted in a sharp decrease of the average grain size. However, high Cu contents (4% and 6%) caused the structure ordering to B2. The hardness increased after adding Cu. A high Cu content was not benefit to the plasticity. The yield strength increased slightly at 2% and 6% Cu, but decreased a lot at 4% Cu.

Characteristics of Flow Curves and Constitutive Equation of NickelBased P/M Superalloy FGH98

LIU Yang, TAO Yu, JIA Jian

2011, 31(6): 12-18.

[Abstract](1839) [PDF 5726KB](724)

Abstract:
Based on the data of hotcompressing tests which were carried out at temperature ranged from 1050℃ to 1110℃ and strain rate from 0.01s-1 to 1s-1, a system of flow curves of the new type 3rd generation nickelbased superalloy FGH98 was obtained .Then they were used to uncover how the flow stress changes by the change of temperature and strain rate as well as strain.It shows that the curve takes on a typical agitation charateristic and the flow stresses are very sensitive to temperature and strain rate.Subsequently, Arrehenius equation was selected as a model of the constitutive relationship, and the relative parameters were figured out by linear regression analysis of the experimental data with simple error analysis.Then the constitutive equation has been established.

Hot Deformation Behavior of 23Co14Ni12Cr3MoE UltraHigh Strength Steel

WANG Chun-xu, LIU Xian-min, TIAN Zhi-ling, WANG Rui, LI Jian-xin

2011, 31(6): 19-23.

[Abstract](1856) [PDF 4217KB](561)

Abstract:
The hot compression deformation behaviors of secondary hardening ultrahigh strength 23Co14Ni12Cr3MoE steel with high strength and toughness were investigated by use of Gleeble3800 simulator at the temperature range of 1123K to 1423K and at the strain rate of 0.5~10s-1. The corresponding flow curves were determined and hot deformed microstructures were observed. The results show that the flow stress and peak strain increase with increasing strain rate or decreasing deformation temperature. At true strain 0.8 and the strain rate of 0.5~10s-1, the temperature of full dynamic recrystallization increase with the strain rate rising. When the strain rate is 10s-1， the deformation temperature is beyond 1373K， the full dynamic recrystallization is occurred. The hot deformation activation energy Q of steel is 421.6kJ/mol, and the hot deformation equation is derived based on the experiments

Effects of Solution Treatment on Mechanical Properties and Microstructure of Al-Cu-Mg Alloy with Ag Addition

LU Zhi-lun, PAN Qing-lin, CHEN Qin, CAO Su-fang, LIU Xiao-yan, HE Yun-bin

2011, 31(6): 24-29.

[Abstract](1771) [PDF 6373KB](731)

Abstract:
Effect of solution treatment on mechanical properties and microstructure of Al-Cu-Mg alloy with Ag addition was studied by using optical microscopy（OM），scanning electron microscopy（SEM），transmission electron microscopy（TEM），differential scanning calorimeter （DSC），and tensile test. Results show that the most suitable solution treatment process of the alloy is solutionizing at 515℃ for 1.5 h. After aging treatment at 185℃ for 4 h，tensile strength and elongation of the alloy are 503 MPa and 12.3%， respectively. The mechanical properties of the alloy increase first with increasing solution temperature and time，then decrease with solution temperature over 515℃（holding time is 2h）or solution time（solution temperature is 515℃ ） longer than 1.5 h. The lower solution temperature and less solution time result in a less resolution of excess phases and produce a lower strength of the alloy. However，too high solution temperature and excessive solution time easily lead to overburn of the specimens. The overburned temperature of the alloy is demonstrated at 525.9℃. The solution temperature has stronger influence on mechanical properties and microstructure of this alloy than the solution time.

Influence of Deposition Temperature on Microstructure of Zirconium Silicate Coating Prepared by Hydrothermal Electrophoretic Deposition Process

LIU Jia, CAO Li-yun, HUANG Jian-feng, XIN Yu, WU Jian-peng

2011, 31(6): 30-29.

[Abstract](1480) [PDF 2061KB](464)

Abstract:
Zirconium silicate (ZrSiO4) coating was deposited on the surface of C/CSiC composite by a hydrothermal electrophoretic process. The phase composition and microstructure of the prepared multilayer coating were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The influence of deposition temperature on the microstructure of ZrSiO4 coating was investigated. The isothermal oxidation performances of the coating were tested. Results show that the deposition temperature plays an important role in improving the microstructure of zirconium silicate coating. The deposition amount of coating increases with the increase of deposition temperature. The coating deposition rate is controlled by the diffusion rate of charged Zirconium silicate particles. The deposition activation energy of zirconium silicate coating is calculated to be 25.45 kJ/mol during hydrothermal electrophoretic process. After 25h oxidation, the weight loss of C/C-SiC zirconium silicate coating of the coated sample is less than 2%.

Preparation of ZrC Film by Transporting Solid ZrCl₄ during Low Pressure Chemical Vapor Deposition

LIU Gang, LI Guo-dong, XIONG Xiang, WANG Ya-lei, CHEN Zhao-ke, SUN Wei

2011, 31(6): 36-42.

[Abstract](1654) [PDF 2374KB](416)

Abstract:
ZrC film was deposited by chemical vapor deposition(CVD) with ZrCl 4-CH 4-Ar system, and ZrCl4 was transported in solid. The characters of the ZrC film were analyzed by chemical thermodynamics calculating and experimenting. The composition, surface morphology and microstructure were studied by Xray diffractometry and scanning electron microscopy. The results show that this way falls down the chemical vapor deposition temperature. And it is easy to get widespread homogeneous ZrC film in structure. The film surface is formed by grains within the size of 20-80nm, and shows anomalous farmland organization. The film structure is mainly for columnar crystal which grows preferentially in the plane（200）. In addition, the formation mechanism of the farmland organization and the growth mechanism of the ZrC film were analyzed.

Improving TiAlBased Alloy High Temperature Properties by Plasma Surface Cr-Si Alloying

LI Ya-fei, ZHANG Pin-ze, XU Hao

2011, 31(6): 43-49.

[Abstract](1552) [PDF 6543KB](401)

Abstract:
Plasma alloying of Cr-Si on TiAl-based alloy was achieved by using Double Glow Plasma Surface alloying technology. Morphology，content of elements and phase composition were characterized by means of SEM, EDS and XRD. High temperature oxidation resistance and wear resistance of alloyed layer were also investigated. The results show that the phase in alloyed layer is composed of Cr3Si and Laves phase TiCr 2. The phases in transition layer are Al 8Cr 5 and Al 3Ti. The concentration of Cr and Si displays gradient distribution. Dense CrO2 and continuous protective Al 2O 3 film were formed in the process of oxidation. The curve of oxidation kinetics was parabolic. The extent of abrasive wear and oxidation wear decreased dramatically due to the plasma alloying process. Relative wear resistance of alloying layer had enhanced 17.3 times.

CdSeS Alloyed Quantum Dots and its Nonlinear Composition Effect

WAN Zhen, FU Hong-hong, YUAN Bin-xia, LUAN Wei-ling

2011, 31(6): 50-54.

[Abstract](1595) [PDF 1835KB](454)

Abstract:
Alloyed quantum dots (QDs) own tunable absorption and photoluminescence (PL) properties via the variation of chemical composition. Capillary microfluidic reactor was utilized for the controlled synthesis of ternary CdSeS QDs in an accelerated manner. The experimental results show that the synthesis conditions including the synthetic temperature and the concentration of precursors play important role in the PL properties of CdSeS QDs, the PL wavelength ranged from 520 nm to 629 nm is continuously adjusted. Moreover, the nonlinear composition effect was proved. The successful formation of alloyed QDs was confirmed by transmission electron microscopy (TEM), Xray diffraction (XRD) and Energydispersive Xray spectroscopy (EDS) study. Besides, CdSeS/ZnS core/shell QDs with excellent color purity were prepared aiming at the improvement of PL quantum yields.Key words: CdSeS QDs; microreaction; nonlinear effect

Prepared and Electromagnetic Properties of La Doped Strontium Ferrite/Polymer Composite

ZHAI Qing-xia, HUANG Ying

2011, 31(6)

[Abstract](1579) [PDF 3005KB](464)

Abstract:
To compare the electromagnetic properties of Ladoped strontium ferrites nanocomposite in different form, strontium ferrites particle doped with La were synthesized by solgel, strontium ferrite/PANI nanocomposites were prepared by in situ polymerization method, La doped nanostrontium ferrite/PSS film and SrLa0.4Fe11.6O19/PSS/PANI multlayers film were prepared by electrostatic selfassembly technique. The structure, morphology and ferromagnetic property of ferrite particle and nanocomposites were characterized by Xray powder diffractometer (XRD), Fourier transform infrared spectra (FTIR), Transmission electron microscope (TEM), Xray photoelectron spectrum（XPS）, Magnetic vector network analyzer and vibrating sample magnetometer (VSM) . The results indicate that at 9.21GHz，the strength of microwave absorption properties of all is: (SrLa0.4Fe11.6O19/PSS/PANI)8 multilayer film SrLa0.4Fe11.6O19/PANI particle SrLa0.4Fe11.6O19 particle, (SrLa0.4Fe11.6O19/PSS/PANI)8 multilayer film has higher saturation magnetization Ms and coercivity Hc as compared with the particle SrFe12O19 and SrFe12O19/ PANI composite materials. (SrLa0.4Fe11.6O19/PSS/PANI)8 multilayer film has fine electromagnetic performance.

Preparing Electrically Conductive Acrylate Pressure Sensitive Adhesive Filled with Graphite Nanosheet

ZHANG Yi, QI Shu-hua, DUAN Guo-chen, WU Xin-ming

2011, 31(6)

[Abstract](1707) [PDF 2789KB](669)

Abstract:
The electrically conductive pressure sensitive adhesive, comprising acrylate resin and graphite nanosheet (NanoG) as conductive filler, was prepared by solution blending method. The structures of NanoG and the electrically conductive pressure sensitive adhesive were characterized though scanning electron microscopy (SEM), fourier transmission infrared (FTIR) and transmission electron microscope (TEM). Results show that the NanoG had a diameter ranging 1-10m and thickness ranging 20-80nm and homogeneously dispersed in forming conducting network in the electrically conductive pressure sensitive adhesive. The FTIR reveals that the hydrogen bonding was formed between pure acrylate resin and NanoG. The electrical conductivity of the electrically conductive pressure sensitive adhesive increased to 1.2810-2 S/cm when the content of the conductive filler was 40%. The 180 peel strength of the electrically conductive pressure sensitive adhesive decreased gradually with the filler content increased. While the shear strength increased when the content of the filler increased from 0% to 20%.

Unidirectional Ramie Fiber Reinforced Composite Based on Phenolic Resin

LIU Yan-feng, BAO Jian-wen, LI Yan-liang, YI Xiao-su

2011, 31(6)

[Abstract](1720) [PDF 2444KB](556)

Abstract:
(Science and Technology on Advanced Composites Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095,China)Abstract： The unidirectional ramie fiber reinforced composite based on Cycom6070 could be phenolic resin was prepared and the thermal and mechanical properties of resin, fiber and composite were studied. The results show that after cure for 1h at 100 ℃, the lowest complex viscosity of Cycom6070 resin increase from 0.1 Pas to 3.6 Pas, It could be used to produce prepreg. TGA curve indicates when the temperature increases to 200 ℃, the weight loss of ramie fiber is about 8%, and when the temperature is higher than 200 ℃, the weight loss curve is sharply declined. Mechanical properties of composite reinforced by unidirectional ramie fiber modified by coupling agent are much higher than those of composite reinforced by ramie fiber without modifying. SEM photographs show that coupling modification increases the compatibility between the resin and fiber in composite.

Damage and Failure Mechanism Analysis of 3D FiveDirectional Braided Composites with Interface Debonding under Unidirectional Tension

HANG Chao, XU Xi-wu, GUO Shu-xiang

2011, 31(6)

[Abstract](1559) [PDF 2536KB](449)

Abstract:
A nonlinear finite element model with interface phase was presented to simulate the damage and failure of 3D fivedirectional braided composites under unidirectional tension. TsaiWu and Mises criterions were considered for initial damage prediction of yarns and matrix. Quads failure criteria was adopted to identify the onset of debonding of the interface. An anisotropic damage model was used to analyze the damage evolution of yarns those damage modes were characterized by Murakamis damage tensor. In addition, a isotropic damage model was used to matrix and interface. The whole process of damage initiation, propagation and catastrophic failure of fivedirectional braided composites with typical braided angle were simulated in detail. The damage mechanisms were revealed in the simulation process and the strength of the braided composites was predicted from the calculated stressstrain curve. The numerical results show good consistent with experiment results, which verifies that the proposed simulation method is very useful for the evaluation of damage mechanisms of 3D fivedirectional braided composites

Exploration of Several Influence Factors of Low-Velocity Impact Damage on Composite Laminates

QU Tian-jiao, ZHENG Xi-tao, FAN Xian-yin, ZHENG Xiao-xia

2011, 31(6)

[Abstract](1797) [PDF 1841KB](447)

Abstract:
Damage of composite laminates due to lowvelocity impact depends on number of factors. The simulation of composite laminates damage is carried out with ABAQUS software. Several influence factors are analyzed in order to foresee the damage resistance of composite laminates in the early stage with the method which regards damage area as the singlevariable parameter. Delamination is one of leading damage forms of laminates. Based on damage mechanics, fracture mechanics and cohesive theory, cohesive unites are constituted in this paper to simulate delamination accurately. The point of inflexion is a central characterization of damage resistance. Based on the experiments and finite element model, damage resistances of different laminates are determined by contrasting diverse inflexion value which can be calculated on impact forcetime curves. The rationality of the model has been confirmed by the lowvelocity impact test.

Compression Failure Behavior of Composite Laminates with Lowvelocity Impact Damage

LIU Jie, FAN Jin-juan, WANG Yun-ying

2011, 31(6)

[Abstract](1566) [PDF 6811KB](451)

Abstract:
The effect of visuallyundetected and detected damages on the compression failure behavior of CF3052/5224 composite laminates after impact was studied. Lowvelocity impact and compression tests were carried out on the composite laminates. The failure modes of the composite laminates with the two type damages were compared. And the knee point in the relationship curve of the impacted pit depth with impaction energy variation was analyzed. The results show that the main failure mode of the composite laminates with visually-undetected damage is crack and delamination of the matrix. However, the composite laminates with visuallydetected damage, besides crack and delaminating of the matrix, fiber fracture is seen. The micro buckling feature caused by impacting exists at the side fracture surface of the impaction damage central region, and the brim of the impaction damage region is not affected. The failure mode of the composite laminates with damage is a shearing and delaminating failure, the same as the undamaged composite laminates.

Compressive Strength of 2DC/SiC Composite at High Temperature in Air

NIU Xue-bao, ZHANG Cheng-yu, QIAO Sheng-ru, HAN Dong, LI Mei

2011, 31(6)

[Abstract](1791) [PDF 2238KB](413)

Abstract:
The compressive strength of a two dimensional carbon fiber reinforced silicon carbide composite (2DC/SiC) at elevated temperature in air was studied. The plain weaved carbon cloth was applied as reinforcement, made of stacked and seamed 1K T300 carbon fiber cloth. The 2DC/SiC was prepared by isothermal chemical vapor infiltration. The specimens were coated with SiC by chemical vapor deposition. The tests were conducted at room temperature, 700℃, 1100℃ and 1300℃ respectively, and the loading direction was perpendicular to 2DC/SiC plane. The fractured surface of the specimens was observed by a scanning electron microscope. The results show that the compressive strength increases gradually with increasing the temperature from room temperature to 700℃, while it decreases gradually when the temperature was above 700℃. The residual stress caused by the mismatch between the thermal expansion coefficients of the fiber and matrix, and the oxidation products play important roles in determining the compressive strength.

ThermalMechanical Fatigue Performance of Powder Metallurgy Superalloy FGH95 and FGH96

ZHANG Guo-dong, HE Yu-huai, SU Bin

2011, 31(6)

[Abstract](1589) [PDF 732KB](389)

Abstract:
Inphase(IP)and Outofphase(OP) thermalmechanical fatigue(TMF) behavior of powder metallurgy (PM) superalloy FGH95 and FGH96 were studied with maximum and minimum temperature of 350℃and 600℃. Stressstrain loop, cyclic stress response and fatigue life of TMF in two kinds of superalloy were analyzed. Stressstrain loop of TMF showed the characteristic of tensioncompression symmetry and of low plasticity with high strength. Cyclic stress response depended on magnitude of stain. At the same strain amplitude, it is found that the TMF cyclic stress of FGH96 is lower than the TMF cyclic stress of FGH95 alloy, and the cyclic plasticity of FGH96 alloy is more better than the cyclic plasticity of FGH95 alloy. Consequently TMF performance of FGH96 alloy is better than TMF performance of FGH95 alloy.

2011 Vol. 31, No. 6