航空材料学报

2017-03-Catalog

2017, 37(3): .

[Abstract](1074) [PDF 875KB](6)

Abstract:

Effect of Cu Content on Microstructure and Properties of 2219 Aluminum Alloy Forgings and Its Welded Joints

Jun XING, Kanghua CHEN, Songyi CHENG, Yunqiang CHEN, Fang YU, Debo LIU

2017, 37(3): 1-8.

[Abstract](2800) [FullText HTML] (1309) [PDF 5090KB](19)

Abstract:
The influence of Cu content on microstructure and properties of 2219 aluminum alloy was investigated by using tensile tests, welding tests, electrochemical impedance spectroscopy (EIS), cyclic anodic polarization curves (Tafel) combined with optical microscopy (OM) and scanning electron microscopy analysis (SEM). The results indicate that the residual crystal phase in the matrix of 2219 aluminum alloy is reduced with the decrease of Cu content which contributed to effectively suppress the precipitation of Al₂Cu coarse phase during the welding process. Furthermore, with the decrease of Cu content, elongation of the alloy is significantly increased, while the tensile strength and yield strength is slightly decreased. At the same time, Al₂Cu phase formed in the matrix induces localized corrosion which causes the deterioration of corrosion resistance in the alloy, while the corrosion tendency of the alloy can be reduced by the decrease of Cu content and the corrosion resistance of the alloy is improved.

Effect of C Content on Microstructure of Second Generation Single Crystal Superalloy

Shizhong LIU, Zhenxue SHI, Jiarong LI

2017, 37(3): 9-15.

[Abstract](2912) [FullText HTML] (1290) [PDF 5817KB](25)

Abstract:
The single crystal superalloy with different C contents was casted using master alloy of DD6 in the directionally solidified furnace. The effect of C content on the microstructure of the second generation single crystal superalloy was investigated. The results show that C content has no obvious effect on the dendrite arm spacing. With the increase of C content, the volume fraction and size of γ/γ' eutectic decrease. However, the volume fraction of carbide increases, and its morphologies change from blocky shape to frame work-like and Chinese-script-like with the increase of C content. With the increase of carbon content, the segregation of Ta decreases while the segregation of Re, W, Mo, Nb increases. C content has no obvious effect on the shape and size of γ' phase in as cast microstructure or after heat treatment. The morphology of carbide has no distinct change after heat treatment.

Numerical Simulation of Spheroidization Process of TiAl Alloy Powders in Radio Frequency Plasma

Langping ZHU, Xin LU, Chengcheng LIU, Jianchong LI, Hai NAN

2017, 37(3): 16-23.

[Abstract](3213) [FullText HTML] (1370) [PDF 7207KB](38)

Abstract:
A numerical simulation method was used to study the radio frequency plasma spheroidization process of TiAl alloy powder. The effects of velocity field and temperature field on the motion trajectory and mass change of TiAl alloy powder with different particle size were analyzed.The results show that the temperature of powder particles increases rapidly under high temperature plasma, surface evaporation cause the reduction of particle size, and particles with small size tend to evaporate quickly. The motion trajectory of particles with different sizes in the lower end of the cooling tube is different obviously, small particles tend to enter the air outlet, while the larger particles are easy to fall down to the bottom of the cooling tube to be collected. Increasing air flow rate can improve the velocity of air flow in the spheroidizing system, causing larger particles to be taken away by the air, resulting in yield reduction. The simulation results of TiAl alloy powder spheroidization are close to the experimental results refer to parameters such as powder size distribution, average particle size and powder yield, and the model is in good accordance with the actual process of the spheroidization.

Effect of Low Angle Grain Boundaries on Mechanical Properties of DD5 Single Crystal Ni-base Superalloy

Jianchao QIN, Renjie CUI, Zhaohui HUANG, Jingqian ZHAO, Yipeng ZHANG, Cui ZONG, Shengping CHEN

2017, 37(3): 24-29.

[Abstract](6039) [FullText HTML] (2720) [PDF 4742KB](44)

Abstract:
The effects of low angle grain boundaries on the mechanical properties of second generation single crystal superalloy DD5 were investigated and the test specimens were prepared by using seeds. The results show that at 870 ℃, the yield strength and breaking strength showed no difference when the angle is below 16.1°. The elongation is higher than 15% when the angle is below 11.4°, but the elongation decreases quickly when angle is above 11.4°. At 980 ℃/250 MPa, the rupture life is higher than 130 h when the angle is below 5.1°, and decreased slowly when the angle is above 5.1°. The rupture life still remaines 85% when the angle is 14.8°. But the rupture life decreases quickly when the angle is above 14.8°.At 1093 ℃/158 MPa, the rupture life is higher than 30 h when the angle is below 5.1°, and decreases when the angle is above 5.1°.

Simulation of Flow Stress Characteristic During Two-stage Hot Deformation Process in AZ31B Magnesium Alloy

Xiaohu DENG, Xiaodong HU, Hongyang ZHAO, Dongying JU

2017, 37(3): 30-36.

[Abstract](2874) [FullText HTML] (1184) [PDF 2857KB](11)

Abstract:
A 2-D CA model has been developed to simulate two-stage hot deformation processing of magnesium (Mg) alloy. Based on the fact that Mg has an HCP crystal structure with six-fold symmetry, the model employs hexagonal CA lattice. The physically-based model has integrated the effects of individual metallurgical phenomena related with the hot deformation, including dynamic recrystallization (DRX), static recovery, static recrystallization (SRX), meta-dynamic recrystallization (MDRX) and grain growth, etc. The model is validated by simulating single-stage and two-stage hot compression tests of AZ31B. The effects of temperature, strain rate, the interval and pre-strain on stress-strain curves are investigated. The calculated results are compared with the available experimental findings in AZ31B Mg alloy, and the simulated results agree well with the experimental results and theoretical models.

Influence of Temperature on Mechanical Behavior During Static Restore Processes of Al-Zn-Mg-Cu High Strength Aluminum Alloy

Kun ZHANG, Xiaodong ZHAO, Huiqin CHEN, Liang WANG

2017, 37(3): 37-43.

[Abstract](3388) [FullText HTML] (1255) [PDF 4671KB](20)

Abstract:
Flow stress behaviors of as-cast Al-Zn-Mg-Cu high strength aluminum alloy during static restore processes were investigated by: Isothermal double-pass compression tests at temperatures of 300-400℃, strain rates of 0.01-1 s^-1, strains of 33% +20% with the holding times of 0~900 s after the first pass compression. The results indicate that the deformation temperature has a dramatical effect on mechanical behaviors during static restore processes of the alloy. (1) At 300 ℃ and 330 ℃ lower temperatures, the recovery during the deformation is slow, and deformation energy stored in matrix is higher, flow stresses at the second pass deformation decreased during the recovery and recrystallization, and the stress softening phenomena is observed. Stress softening is increased with the increasing holding time; Precipitation during the holding time inhibites the stress softening. (2) At 360 ℃ and 400 ℃ higher temperatures, the recovery during deformation is rapid, and deformation energy stored in matrix is lower. Solid solubility is higher after holding, so that flow stress at the second pass deformation is increased, stress hardening phenomena is observed. Stress hardening decreased with the increasing holding time duo to the recovery and recrystallization during holding period at 360 ℃; Precipitation during holding also inhibited the stress softening. However, Stress hardening remains constant with the increasing holding time duo to the reasanenal there are no recovery and recrystallization during holding period at 400 ℃.

Pulse Current Assisted TLP Bonding of SiC_P/Al Composites Sheet Using Powders Interlayer

Bo WANG, Xiaoming LAI, Zhuoxun YI, Kaifeng ZHANG

2017, 37(3): 44-49.

[Abstract](2871) [FullText HTML] (1241) [PDF 2514KB](17)

Abstract:
The powders interlayer was applied for transient liquid phase (TLP) bonding of SiC_p/Al composites using pulse current heating. Pulse current got though the joint with powder interlayer and generated the effect of Joule heat and spark plasma sintering to achieve the TLP bonding of SiC_p/Al composites sheet. The results show that there is the good TLP bonded joint without defects under the conditions of vacuum:1.39×10³ Pa; Pulse current density: 115 A/mm²; holding time: 15-60 min; original pressure: 0.5 MPa. The results reveal the dense joint without pores composed of the Al-based solid solution, pure Ti zone, Al₂Cu, and Al₃Ti intermetallic phase. Furthermore, the thermal and isothermal effects of pulse current on in situ synthesis of TLP bonded joints of SiC_p/Al composites using mixed Al-Cu-Ti powder interlayer are analyzed and discussed. According to microstructure of joint, pulse current promote to in situ form the intermetallic compound, which can provide higher mechanical properties of joint.

Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Alloy Using Cobalt-base Brazing Alloy

Hui PAN, Haisheng ZHAO

2017, 37(3): 50-55.

[Abstract](3027) [FullText HTML] (1455) [PDF 2578KB](17)

Abstract:
Vacuum brazing of K465 superalloy was carried out by using Co45NiCrWB cobalt-base filler metal at 1220 ℃ for different holding time, and the joint clearance was 0.5 mm pre-filled with FGH95 nickel-base superalloy powder. The effect of the structural constitution of brazed different holding time of temperature on the brazed joint microstructure and properties. The results show that the brazing seam is composed of alloy powder particles and borides among them. It is two-phase structure of γ and γ' with a few small blocks of borides in the powder particles, and there exists phases rich in Cr, W and Nb elements. The powder particles are growing along the holding time during the brazing process, while their combination is expanded. It is good for stress rapture properties of joints that borides was fine in brazing seam with more superalloy powder and proper holding time. And the joints brazed for 30-60 min show higher stress rapture properties.

Anti-laser Irradiation Ability of VO₂ Films Against Pulsed Power Laser

Ye TIAN, Fei LUO, Dabo LIU, Hongfei QI, Dongsheng CHEN, Bingwei LUO, Haitao ZHOU, RYZHKOV Mikhail

2017, 37(3): 56-60.

[Abstract](3065) [FullText HTML] (1400) [PDF 1931KB](27)

Abstract:
Thermochromic VO₂ film was fabricated on quartz substrate through sputtering oxidation coupling method, and its optical properties were also investigated. Results show that the prepared VO₂ film exhibits good thermo-optical switching performance under weak light irradiation, while large transmittance changes both in the visible and near-infrared light area. Under the condition of pulsed power laser irratiating, large optical modulation depth is also derived in the infra-red region. With the increase of pulsed laser energy, the scattering coefficient is gradually decreased, and the anti-laser irradiation ability is firstly appeared to have a decline trend after an initial ascent. The minimum transmittance value can reach to 7% and the laser damage threshold is about 50 mJ/cm².

Microstructure and Mechanical Properties of Laser Melting Deposited TA15+Ti₂AlNb Alloys

Yantao LIU, Yongzhong ZHANG, Yiqiang CHEN, Yangjie TANG

2017, 37(3): 61-67.

[Abstract](2878) [FullText HTML] (1383) [PDF 3494KB](20)

Abstract:
Three different proportions of TA15 and Ti₂AlNb alloy powde were premixed and thin-walls with proportions of 40%TA15+60%Ti₂AlNb, 50%TA15 +50% Ti₂AlNb and 60%TA15+40%Ti₂AlNb (mass fraction) were prepared by using laser melting deposition process. The composition, microstructure and mechanical properties of the three thin-walls were analyzed. The results indicate that the compositions of all the three kinds of alloys are uniform. The alloy appears as basketweave microstructure with acicular α phase and α₂ phase distributing within primary β/B2 grain. Tensile strength of the three kinds of alloys are 1108 MPa and 1071 MPa, 1105 MPa, and elongation are 3.0%, 2.2% and 3.8% respectively; Tear ridge along α₂ phases is visible on tensile fracture surface, and the fracture mode is subject to cleavage fracture.

Mechanical Properties of TC4 Matrix Composites Prepared by Laser Cladding

Lin WANG, Chunyang YAN, Dongyuan WANG, Yongzhong ZHANG

2017, 37(3): 68-72.

[Abstract](3266) [FullText HTML] (1332) [PDF 2872KB](16)

Abstract:
In order to improve the penetration performance of TC4, the direct laser deposition technology was used to prepare TC4 composite material. TA15+30% TiC powder, TA15+20%Cr₃C₂ powder and TA15+15%B₄C powder were used as deposited materials for TC4 matrix. The micromorphology, change of hardness of the deposited coating and mechanical properties of the three composites were studied. The experimental results demonstrate that the TC4 matrix with the three kinds of materials can form a complete metallurgical bonding, and the strength of TC4-(TA15+TiC), TC4-(TA15+Cr₃C₂) and TC4-(TA15+B₄C) are higher than that of TC4 matrix materials, while the plasticity is slightly worse.

Phase Composition and Microstructure of Hot-Pressing Sintered Ti₂AlN Metal-Ceramic Bulk Material

Suying LIANG, Ju KANG, Xia ZHAO, Zaiji ZHAN

2017, 37(3): 73-77.

[Abstract](2844) [FullText HTML] (1272) [PDF 2239KB](13)

Abstract:
Ti₂AlN metal-ceramic bulk material was fabricated by hot-pressing sintering (HPS) using TiN, Ti and Al powder in a stoichiometric ratio of 1:1:1.03 after mechanical mixing. XRD, SEM and TEM were employed to investigate the phase composition and microstructures of the products. The results show that the high purity Ti₂AlN can be obtained by HPS at 1300 ℃ for 2.5 h. The sintered Ti₂AlN presented a hexagonal system layered structure with an anisotropy. Twins are found in the Ti₂AlN. There were a few nano-scale TiN particles in the products.

Effects of Novel Structure Bonding Materials on Properties of Aeronautical Acrylic

Zhisheng LI, Hongfeng ZHANG, Lei LI, Yue YAN

2017, 37(3): 78-83.

[Abstract](2865) [FullText HTML] (1294) [PDF 1691KB](22)

Abstract:
Novel structure bonding materials, J-351 epoxy adhesive film with low curing temperature and liquid modified acrylate SY-50s adhesive were chosen and characterized. The effects of adhesives on the mechanical properties of acrylic were studied. The results reveal that both adhesives have excellent bonding properties to acrylic. The stress-solvent crazing value of J-351 is higher than that of SY-50s. With the application of adhesive on the surface, mechanical properties of acrylic are declined. Casting acrylic shows more drastic decline than that of oriented acrylic. Through the characterization of fracture surface, we find that fracture of tensile sample derives from the side with adhesive. Mechanical properties of acrylic are more sensitive to SY-50s, because the liquid adhesive presents integrate bonding interface with acrylic. The interface between J-351 and acrylic is clear, making acrylic insensitive to J-351 film. Edge attachment strength of samples bonded with J-351 are higher than that of samples bonded with SY-50s due to the effects of adhesives on acrylic. J-351 epoxy adhesive film presents preferable application performance in the structure bonding of aeronautical acrylic.

Very High Cycle Fatigue Behavior of TA11 Titanium Alloy

Zehui JIAO, Huichen YU, Bin ZHONG, Xudong LI, Jingyi ZHOU

2017, 37(3): 84-90.

[Abstract](3079) [FullText HTML] (1285) [PDF 2782KB](33)

Abstract:
The conventional fatigue test method was used to obtain the very high cycle fatigue (VHCF) limits of 3×10⁷ and 1×10⁸ cycles for TA11 titanium alloy in different temperatures and stress ratios. Three parameter power function method was used to obtain the VHCF median S-N curves and equations. The results show that the VHCF strength of 3×10⁷ and 1×10⁸ cycles presented a continue reducing trend compared with the traditional 1 x 10⁷ fatigue limit. This trend is not obvious in negative stress ratio (R=-1), but significant in normal stress ratio (R=0.1 and 0.5), and the reduction amplitude of room temperature tests was greater than that of elevated temperature tests. The fracture morphologies showed that the VHCF cracks initiat at the specimen surface of TA11 alloy in room temperature tests, and the VHCF cracks initiation ways in elevated temperature tests relate to the stress ratio. The cracks initiate at the specimen surface when R=0.1 and 0.5 but in the internal when R=0.5; The surface state of TA11 alloy specimens is the main cause of its fatigue life dispersion.

Analysis and Experimental on Aircraft Insulation Thermal Bridge Effect

Tian XIA, Ping XU, Lei SHANG, Ao WANG

2017, 37(3): 91-96.

[Abstract](3579) [FullText HTML] (1353) [PDF 2807KB](16)

Abstract:
Two kinds of typical aircraft insulation structures were designed for the heat bridge in the metal ribs of aircraft insulation structures. In order to study the influence of heat bridge effect on thermal insulation performance, each configuration was analyzed by the transient heat transfer FEA, check point temperature was obtained in the hot surface temperature of 100 ℃, 200 ℃, 300 ℃, 424 ℃ respectively, and the validity of FEA was proved by insulation performance experiment. The result showed that the thermal bridge has a great influence to the insulation performance of insulation structure, and the thermal bridge influence should be considered adequately when the insulation structure designed. Additionally, the blocking method for thermal bridge is also put forward.

2017 Vol. 37, No. 3