航空材料学报

2019-01目录

2019, 39(1): .

[Abstract](2680) [FullText HTML] (1295) [PDF 1000KB](19)

Abstract:

Research progress on corrosion behavior of magnesium-lithium alloys

Baojie WANG, Chunlong JIANG, Chuanqiang LI, Jie SUN, Daokui XU

2019, 39(1): 1-8.

[Abstract](5439) [FullText HTML] (2939) [PDF 635KB](73)

Abstract:
Research progress on corrosion behavior (localized corrosion, corrosion type and corrosion products) and the effects of processing methods and alloying on the corrosion resistance of hexagonal close packed (HCP) singular phase, body cubic centered (BCC) singular phase and (HCP+BCC) duplex structured Mg-Li alloys were summarized. The future research directions about how to improve the corrosion resistance of Mg-Li alloys were pointed out and the research on corrosion behavior of Mg-Li alloys should focus on the structure, main components and evolution of surface product layers. Meanwhile, it is necessary to consider the effect of alloying elements on the protective effect of surface film layers, and to study the influence of the crystallographic texture of Mg-Li alloys due to the severe plastic deformation on their corrosion behavior.

Effects of single-side and double-side friction stir processing on microstructure and properties of Mg-Zn-Y-Nd alloy thick plate

Xuexue XU, Shijie ZHU, Qing WANG, Liguo WANG, Yufeng SUN, Shaokang GUAN

2019, 39(1): 9-16.

[Abstract](2586) [FullText HTML] (1377) [PDF 984KB](34)

Abstract:
In order to obtain a large modified zone with uniform microstructure and good comprehensive properties, single-side and double-side friction stir processings of Mg-Zn-Y-Nd alloy thick plate were carried out, and the microstructure and properties of the processed plates were studied. The results show that the microstructure of the alloy is obviously refined after friction stir processing. The average grain sizes of the upper, mid and lower samples in the stirring zone after single-side and double-side friction stir processings are 4.45 μm, 5.08 μm,5.30 μm and 3.93 μm, 3.20 μm and 3.19 μm respectively. Compared with the homogenizing annealing alloy and single-side friction stir processed alloy, the microstructure of the double-side friction stir processed alloy is more uniform and fine, and the tensile strength and elongation of the lower stirring zone are the highest, 283.3 MPa and 23.9% respectively, and also the corrosion resistance is the best. The corrosion mode is changed from pitting corrosion to uniform corrosion.

Preparation and corrosion resistance of titanium-containing coating on AZ31B magnesium alloy

Xiaoting SHI, Yuanyuan ZHU, Guoqiang LI, Shufang ZHANG, Rongfang ZHAO, Yijia ZHANG, Rongfa ZHANG

2019, 39(1): 17-25.

[Abstract](3220) [FullText HTML] (1526) [PDF 1143KB](42)

Abstract:
The titanium-containing oxide film has attracted attention due to the phenomenon of self-sealing pores. The influences of fluorotitanate (K₂TiF₆), phytic acid (H₁₂Phy) and sodium fluoride(NaF) concentrations as well as final voltage on corrosion resistance of oxide film were investigated by an orthogonal experiment with four factors and three levels. The coating performances were characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical methods. The results show that the sequence of processing factors on the corrosion resistance of oxide film is H₁₂Phy concentration > NaF concentration > final voltage > K₂TiF₆ concentration. Anodic coatings are mainly composed of TiO₂, MgF₂, Mg₂PO₄F and Mg₂TiO₄. Micro-arc oxidation (MAO) coating can significantly improve the corrosion resistance of magnesium alloy. However, with the prolonging of immersion time, the coating corrosion resistance decreases.

Corrosion resistance of a magnesium hydroxide/stearic acid composite coating fabricated by vapor diffusion method on Mg-Li-Ca alloy

Hanpeng LIU, Lanyue CUI, Zhuangzhuang HAN, Shuoqi LI, Rongchang ZENG

2019, 39(1): 26-37.

[Abstract](3533) [FullText HTML] (1402) [PDF 8608KB](38)

Abstract:
A composite coating of magnesium hydroxide/stearic acid on surface of Mg-1Li-1Ca alloy was prepared using vapor diffusion method to improve the corrosion resistance. The surface morphology and chemical composition of the films were characterized by high resolution scanning electron microscopy (HRSEM), Fourier transform infrared spectrometer (FTIR) and X-ray diffraction analysis (XRD). Electrochemical experiments and immersion test were conducted to study corrosion resistance of the obtained composite coating.The formation and degradation mechanisms of the composite coating were proposed.The results show that the magnesium hydroxide coating has a petal-like structure and is well-adhered to the surface of Mg-1Li-1Ca alloy.The stearic acid coating does not change the petal-like structure of the magnesium hydroxide coating. However, the stearic acid can effectively prevent the aggressive medium penetrating into the internal coating due to its low surface energy and good hydrophobicity.The corrosion current density of the magnesium hydroxide/stearic acid (Mg (OH) ₂/SA) composite coating (1.45 × 10^–7A/cm²) is decreased by two orders of magnitude compared to that of the Mg-1Li-1Ca alloy substrate (2.70 × 10^–5 A/cm²), leading to the enhanced corrosion resistance of magnesium alloy.

3D printing technology for titanium alloy and its defect

Chaolan TANG, Jingqing WEN, Weixiang ZHANG, Ruikun CHU, Mei SUN

2019, 39(1): 38-47.

[Abstract](3763) [FullText HTML] (1646) [PDF 850KB](104)

Abstract:
The development of 3D printing technology, basic principles and technical features are introduced. Several major 3D printing technologies of titanium alloy both at home and abroad are reviewed: selective laser sintering technology (SLS), selective laser melting technology (SLM), laser solid forming technology (LSF), electron beam selective melting technology (EBSM) and electron beam fuse deposition forming technology (EBF³). By comparison, EBSM technology is the most promising 3D printing technology for titanium alloy in the future because of its high efficiency, high accuracy, low cost and no pollution. The cause and detection of defects in the process of forming is an important research focus in the field of 3D printing, and it is also the basis of the realization of the application of 3D printing parts. The classification, harm and cause of the main defects (including spheroidization, cracks, porosity and warpage) in the process of 3D printing for titanium alloy, as well as the nondestructive testing technology commonly used in 3D printing are introduced. And combined with domestic and foreign research situation, the methods to restrain or improve the above defects are discussed. Finally, the prospect of the future development of 3D printing technology for titanium alloy is prospected from the aspects of materials, equipment and testing technology.

Effect of composition on microstructure and mechanical properties of TA15 titanium alloy

Nan SUI, Jingxia CAO, Xu HUANG, Fan GAO, Qiming TAN

2019, 39(1): 48-54.

[Abstract](2744) [FullText HTML] (1509) [PDF 762KB](61)

Abstract:
To analyze the relationship between composition, microstructure and mechanical properties of TA15 titanium alloys, the quasi-static tensile properties and dynamic properties at room temperature of four kinds of TA15 titanium alloys were studied by the electronic universal tensile testing machine and split hopkinson pressure bar (SHPB). The results reveal that the Zr content has little effect on the tensile strength at room temperature, moreover, with the increase of content of main alloy elements Al, V and Mo, the content of primary α phase decreases and the lamella width of secondary α phase is thinner which provide higher strength and lower plasticity. Slight changes in alloy composition have little effect on dynamic mechanical properties within the critical strain rate range. Increasing the content of main alloy elements Al, Zr, V and Mo is beneficial to improve the critical strain rate, at which the alloy has excellent dynamic mechanical properties. For equiaxed TA15 titanium alloys obtained under air cooling condition, the smaller volume fraction of primary α phase and thinner lamella of secondary α phase can improve the tensile strength, critical strain rate and dynamic mechanical properties at room temperature.

Fracture behavior of low cycle fatigue and dwell fatigue of Ti6242 titanium alloy under high load

Mingda ZHANG, Jingxia CAO, Nan SUI, Yi ZHOU, Xu HUANG

2019, 39(1): 55-61.

[Abstract](2901) [FullText HTML] (1561) [PDF 1285KB](56)

Abstract:
As one kind of near alpha titanium alloys with excellent mechanical properties, Ti6242 alloy always shows the" dwell fatigue”characteristic, which is similar to other near α or α+β titanium alloys, especially at near room temperature. In this study, the low cycle fatigue and dwell fatigue tests under high load were designed according to the law of dwell fatigue sensitivity rising with the increase of test load. Combining with microstructure observation, mechanical property characterization and failure fracture analysis, the relationship between the microstructure and fracture behavior under high load low cycle fatigue and dwell fatigue tests was analyzed systematically. By summarizing the characteristics of failure fracture under room temperature tensile, high load low cycle fatigue test and high load dwell fatigue test, also comparing the dwell fatigue sensitivity of the Ti6242 alloy in this study with other Ti6242 alloys and other titanium alloys under different loading conditions, it is proved that increasing the fatigue load is a feasible way to characterize the dwell fatigue sensitivity of Ti6242 alloy.

In situ study on aging behavior of WE54 alloy using synchrotron radiation

Jia ZENG, Bijin ZHOU

2019, 39(1): 62-69.

[Abstract](3379) [FullText HTML] (1459) [PDF 1887KB](37)

Abstract:
In situ synchrotron radiation was conducted to characterize the aging process of two kinds of WE54 alloys which were subjected to solid solution treatment (T4) and T4 with a subsequent cold rolling deformation (T4-D) respectively. Results of the in situ aging at 300 ℃ show that the strengthening precipitate phase Mg₃(Nd, Y) (β₁) in T4-D alloy nucleates after aging for 3 min. After aging for 9 min, the intensity of β₁ is reduced, and Mg₁₄Nd₂Y (β) diffraction peaks are observed, which indicates that β₁ is transferred to β. After aging for 36 min, this phase transformation reaches a stable state, and β phase dominates the aging process. For T4 alloy, the nucleation of β₁ begins at 6 min, and the transformation from β₁ to β begins at 18 min. After the phase transformation, β phase begins to dominate the aging process at 78 min. Ex situ transmission electron microscopy (TEM) is also carried out to observe the detailed distribution of β₁ and β. Combining the synchrotron radiation and TEM results, it is found that the pre-deformation promotes the aging process and the formation of netlike precipitations, which enhances the aging strengthening effect.

Microstructure evolution of creep damaged DZ411 superalloy during rejuvenation heat treatment

Wenshu TANG, Junfeng XIAO, Sifeng GAO, Yongjun LI, Qing NAN, Jiong ZHANG

2019, 39(1): 70-78.

[Abstract](2692) [FullText HTML] (1362) [PDF 2369KB](53)

Abstract:
The simple solution and aging treatment processes were adopted to rejuvenate the microstructure of creep damaged DZ411 superalloy. The microstructure evolution of superalloy during rejuvenation process was investigated by OM and SEM, and then the mechanical properties were evaluated by tensile and creep rupture tests. The results show that creep damaged superalloy obtained from interrupted test at the end of secondary stage of creep suffers from the spheroidization and rafting of the prime γ′ phase and vanishing of the secondary γ′ phase, but no creep cavities. It is also found that the solution treatment plays a prime role in dissolution of deformed γ′ phase, and then re-precipitation of fine γ′ phase. The proper solution temperature can effectively avoid incipient melting and recrystallization. The two stages of aging are the dominant procedures of optimizing the size, shape and volume ratio of bimodal size γ′ phase. By the appropriate rejuvenation schedule, the bimodal size γ′ particles with coarse secondary γ′ particles and fine tertiary γ′ particles can be obtained. The average diameters of bimodal size γ′ particles are about 0.38 μm and 0.07 μm, and the volume fraction are 47.5% and 6.5% respectively. Rejuvenation heat treatment can successfully recover the room temperature strength close to that of the original alloy. The creep rupture life and elongation of rejuvenated DZ411 superalloy under condition of 980 ℃/220 MPa are 121 h and 13%, these values are slightly lower than that of the original alloy.

Ballistic impact behavior of thin nickel-base alloy plates at different temperatures

Jiao LIU, Bailin ZHENG, Biao YANG, Xiaoqiang YU, Kai ZHANG, Tongcheng SHI

2019, 39(1): 79-88.

[Abstract](2809) [FullText HTML] (1271) [PDF 1102KB](38)

Abstract:
To study the aeroengine containment capability in high temperature, experiments and numerical simulations of the spherical nosed projectile impacting thin plate under 25 ℃ and 600 ℃ were performed. Experiments were conducted by using a gas gun. Target plates were impacted by bullets with different initial velocities. The effect of temperature and initial velocity on the deformation, failure pattern and energy absorption of the plate were analyzed. The results show that at higher temperature, the deformation of the target plates is greater, the energy absorbed by the target plates is smaller and the critical ballistic velocities are smaller . The petal deformation of the target plate caused by bending is more obvious under 600 ℃. Numerical simulations of the impact were conducted by using an explicit dynamics FE code (LS-DYNA). The Johnson-Cook material model was used to carry out the analysis. The Johnson-Cook material model parameters were obtained by the separated Hopkinson pressure bar (SHPB) experiment at high temperature. The results obtained from the numerical simulations were compared with those from the experiments. Good correlation is found between experiments and numerical simulations.

Correlation between orientation behavior of polyacrylonitrile precursor and structure of nascent fiber

Ruyu RUAN, Dehua XU, Zi LIANG, Lianghua XU

2019, 39(1): 89-95.

[Abstract](2827) [FullText HTML] (1390) [PDF 742KB](45)

Abstract:
Polyacrylonitrile (PAN) precursors with different orientation behaviors were prepared by changing the coagulation bath conditions such as concentration and temperature. The orientation structure of the PAN precursor was determined by the method of sound velocity. X-ray diffraction and optical microscopy were used to investigate the crystalline structure and morphological characterization of nascent fiber, and the correlation between orientation of precursor and structure of nascent fiber was established. The molecular chain orientation ability " a” was defined as the slope of the logarithmic fitting curve of the degree of orientation varying with the drafting ratio, and the relationship between " a” and the crystallinity of nascent fiber was studied. The results show that the higher crystallinity nascent fiber has, the lower drawing ability PAN precursor has, and the higher degree of orientation has under the same drafting ratios. The maximum drafting factor of polyacrylonitrile precursor is significantly affected by radial structure of nascent fiber, it reaches the local maximum when the coagulation bath concentration is 74%. The fiber with high solvent content has higher molecular chain orientation ability than the fiber with low solvent content. The molecular chain orientation ability of precursor increases with the crystallinity of nascent fiber.

Assessing delamination initiation of laminates based on bridging model

Jiajie GU, Zhengming HUANG

2019, 39(1): 96-101.

[Abstract](2756) [FullText HTML] (1502) [PDF 862KB](42)

Abstract:
The laminate is essentially bonded together to form the individual laminate by the matrix, any delamination of the laminate must be initiated from a matrix failure. Based on this viewpoint, the initiation of laminate delamination was predicted through analyzing the stresses of the matrix. A three-dimensional finite element method is used to calculate the stress field of a symmetrically laminated plate under an axial load. A convergence study was performed and an average stress method was proposed to solve the singularity problem. Then the internal stresses in the fiber and matrix were determined in terms of the bridging micromechanics model. Finally, a Mohr criterion was used to detect the failure of matrix. T800/914 angle-plied laminates were considered. The results show that this approach is able to correlate reasonably with the available experimental data.

Thermal post-buckling behavior of ceramic-based FGM circular plates with linear variable thickness

Qinglu LI, Pengfei DUAN, Jinghua ZHANG

2019, 39(1): 102-107.

[Abstract](2902) [FullText HTML] (1612) [PDF 945KB](45)

Abstract:
The governing differential equations of ceramic-based functionally graded material (FGM) circular plate with linear variable thickness along the radius in thermal environment were established. The thermal post-buckling behaviors of variable thickness FGM circular plate made of ceramic and metal in thermal environment were proposed by the method of shooting technique. The characteristic curves of the thermal post-buckling equilibrium paths of the FGM variable thickness circular plate in uniform and non-uniform heating fields are given. The influence of ceramic gradient index and thickness variation coefficient on post buckling behavior is discussed. The numerical results show that the thermal critical load of non-uniform heating field is less than the one under uniform load. The change of radial thickness does not affect the thermal critical load value, but affects the post-buckling equilibrium path. The center deflection increases with the increase of variable thickness coefficient.

2019 Vol. 39, No. 1