航空材料学报

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2020, 40(5): .

[Abstract](3509) [FullText HTML] (2464) [PDF 2262KB](22)

Abstract:

Research progress on meso-structure and mechanical properties of SiC_f/SiC textile composites

Tiantian YANG, Diantang ZHANG, Haipeng QIU, Kun QIAN, Weijie XIE, Ling WANG

2020, 40(5): 1-12.

[Abstract](5313) [FullText HTML] (2421) [PDF 17485KB](49)

Abstract:
SiC_f/SiC textile composites have enormous development potentials in the field of aerospace hot-end component owing to their strong structural design, low density, excellent mechanical properties, high-temperature resistance and oxidation resistance. However, there are few researches on the preparation technology, performance and meso-structure of SiC_f/SiC textile composites. In the long run, it is still the research direction that must be carried out in country’s aviation engine manufacturing. In this paper, the research status of SiC_f/SiC textile composites in recent years is introduced from three aspects: meso-scale structure, mechanical properties and numerical simulation. The research status of SiC_f/SiC textile composites in recent years is summarized, and the basic research of domestic and foreign applications is comprehensively compared. Although the domestic preparation technology has made great progress and reached the international advanced level, it is still in its infancy in terms of component assessment and verification and application. Only by optimizing on the basis of the comprehensive balance of reliability, durability, process and performance, and realizing the synergy of materials and processes, structure and design, can breakthroughs be made in the future development of aeroengines.

Effect of aging time on microstructure and properties of as-cast Fe_56.5Ni₃₀Al_10.5Nb₃ shape memory alloy

Zhaoxia CHEN, Wenyi PENG

2020, 40(5): 13-19.

[Abstract](3770) [FullText HTML] (1891) [PDF 1086KB](20)

Abstract:
A Co-free Fe_56.5Ni₃₀Al_10.5Nb₃ (atom fraction/%) alloy was developed. In the preparation, the as-cast alloy was subjected to aging treatment at 650 ℃ and followed solution treatment directly. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to analyze the microstructure and phases of the alloy. At the same time, the hardness test, compressive strength test, superelasticity test and electron backscatter diffraction (EBSD) test were performed. The results show that, when the aging time range from 0 to 95 h, the alloy can exhibit superelasticity at room temperature with the maximum superelastic strain of 10.62%. There are nano-sized γ′ precipitates and fine β precipitates in the alloy. The γ′ phase is formed in the grain interiors and is most densely distributed when the aging time is 70 h. After the aging time exceeds 70 h, the γ′ phase enters the growth stage. The β phase can be formed both in the grain interiors and in the grain boundaries, and the amount of β precipitates increases with the aging time. The precipitation of the β phase can improve the hardness, but its formation in the grain boundaries is detrimental to the strength. With the increase of aging time, the hardness of the alloy increases continuously, and the compressive strength and superelastic strain first increase and then decrease, and reach the maximum value at the time of 70 h. The nano-sized γ′ precipitates and strong {100}<100> texture in the alloy have a great influence on its superelasticity.

Microstructure and mechanical properties of ultra-high strength TiC_p/Mg-1.4Zn-2.6Ca-0.5Mn nanocomposite after hot extrusion

Kaibo NIE, Zhihao ZHU, Kunkun DENG, Jungang HAN

2020, 40(5): 20-28.

[Abstract](11470) [FullText HTML] (4927) [PDF 2864KB](49)

Abstract:
A uniform distribution of TiC_p nanoparticles was realized in the TiC_p/Mg-1.4Zn-2.6Ca-0.5Mn nanocomposite fabricated by the method of ultrasonic-assisted semisolid stirring. Microstructure and mechanical properties of the nanocomposite before and after extrusion were investigated. The results show that the grains in the dense area of the second phase were smaller than those in the barren area, and the second phase was Ca₂Mg₆Zn₃. Dynamic recrystallization (DRX) occurred in the nanocomposites after extrusion at different temperatures (350 °C, 310 °C and 270 °C). Both the sizes and volume fraction of DRX grains and precipitates size were obviously refined as the extrusion temperature decreased, while the volume fraction of precipitates increased. Ultrafine recrystallized grain structure (≈0.34 μm) with a substantial of fine precipitates appeared in the nanocomposite extruded at 270 °C. The refined grain structure was not only due to DRX, but also the synergistic pinning effect of nano-TiC_p, precipitated MgZn₂ and α-Mn particles. The optimum tensile strength was achieved in the nanocomposites extruded at 270 °C/0.1 mm•s^–1, and the yield strength (YS), ultimate tensile strength (UTS) and elongation to failure (EL)were ≈439.7 MPa、≈460.2 MPa and ≈1.73%, respectively. The grain refinement strengthening with the contribution ratio over 60% to YS increment was much higher relative to thermal expansion effect, Orowan strengthening and dislocation strengthening.

Effect of pre-stretching on the precipitation behavior and mechanical properties of X2A66 aluminum alloy

Changbin DOU, Chun XIONG, Ruichun GUAN, Mang JIANG, Qidong TANG, Jinjun XU

2020, 40(5): 29-37.

[Abstract](4842) [FullText HTML] (2248) [PDF 1117KB](19)

Abstract:
The evolution of aging precipitation behavior and the formation of mechanical properties of X2A66 alloy under different aging heat treatment systems were investigated by using the experimental method combining mechanical properties test and microstructure observation. The research results indicate that the pre-stretching treatment before aging can accelerate the aging response rate of the alloy. In addition, while increasing the precipitation density of T₁ phase, the diameter of T₁ precipitate is decreased, but the thickness of T₁ precipitate is not changed. With the increasing of pre-stretching, the strengthening effect of deformation dislocation increases gradually, and the strengthening effect of T₁ phase precipitation decreases gradually. The pre-stretching of 5% can make the sample to obtain the best strong plastic ratio, and the yield strength, tensile strength and elongation rate are 593 MPa, 611 MPa and 10.7% respectively.

Effect of Co content on microstructure and stress rupture properties of DD15 single crystal superalloy

Zhenxue SHI, Shizhong LIU, Xiaodai YUE, Zhicheng WANG, Jiarong LI

2020, 40(5): 38-44.

[Abstract](3712) [FullText HTML] (2143) [PDF 1078KB](40)

Abstract:
DD15 single crystal superalloys with 9%Co and 12%Co were prepared in a directionally solidified furnace. By keeping the other alloying element contents unchanged, the influence of Co content on the microstructure, phase stability and stress rupture properties of the single crystal superalloy under the condition of 980 ℃/300 MPa was investigated. The results show that the primary dendrite arm spacing increases and the volume fraction of γ/γ′ eutectic decreases with increasing of Co content. The size of γ′ phase has no obvious change, its cubic shape turns a little irregular, its volume fraction decreases with increasing of Co content. The microstructure stability of the alloy increases with increasing of Co content. Increasing Co content decreases the stress rupture properties of the alloy.

Effect of microstructure on tensile deformation behavior of Ti-3Al-4.5V-5Mo titanium alloy

Xingwu LI, Aixue SHA, Bo CHEN, Junpeng CHU

2020, 40(5): 45-52.

[Abstract](4019) [FullText HTML] (2238) [PDF 1032KB](282)

Abstract:
The effect of grain size and crystal orientation on the tensile deformation behavior of Ti-3Al-4.5V-5Mo titanium alloy was studied by using scanning electron scanning electron, X diffraction instrument and theoretical calculation. The results of tensile test of the wires in different states have verified that there are obvious macroscopic yield points on true stress-true strain curves of 720-840 ℃ annealing structures, and then a stress drop occurs. When the crystal orientation of α phase all shows <0001> fiber texture of different wires, the grain size determines the macroscopic yield stress of the wire. The larger the grain size is, the lower macroscopic yield stress is. Compared with <0001> fiber texture, the existence of <${10 \overline 10}$> fiber texture of α phase generates larger plastic deformation in α phase, the internal stress in β phase, increased, and the macroscopic yield strength of the alloy decreased.

The microstructure and properties of CoCrAlYSi-hBN coating prepared by HVOF

Ang ZHANG, Changliang WANG, Tianying WANG, Junguo GAO, Mengqiu GUO, Yongjing CUI, Haoliang TIAN

2020, 40(5): 53-59.

[Abstract](4005) [FullText HTML] (2078) [PDF 868KB](22)

Abstract:
CoCrAlYSi-hBN coating was fabricated using the high-velocity oxygen fuel (HVOF) process under several processing conditions, and the effects of process parameters, gas flow and spray distance, on the microstructure and properties of the coating were investigated in the present paper. The microstructure, hardness, bonding strength and chemical composition of the coating was researched by using scanning electronmicroscopy (SEM), microhardness tester, adhesive strength measuring and energy dispersive spectroscopy (EDS). The results show that with the increasing gas flow, the porosity and h-BN content of the coating are reduced, and the hardness is improved; However, the bonding strength increases first and then decreases due to excessive energy leading serious oxidation. With the increase of spraying distance, the oxide inclusions are increased, which causes the hardness of coatings increase and the bonding strength decrease. In addition, when the spraying distance is 225 mm, the hardness and bonding strength of the coating are the highest due to the low porosity and boron nitride content.

Inhibition of interface reaction of DZ22B alloy and high purity Al₂O₃ mould surface by changing directional solidification process parameters

Yantao LIU, Manping LIU, Shaochun SUN

2020, 40(5): 60-69.

[Abstract](3694) [FullText HTML] (2081) [PDF 1013KB](16)

Abstract:
The effect of casting temperature and withdrawal rate on the interfacial reaction between DZ22B nickel-base superalloy and high-purity Al₂O₃ ceramic shell facecoat material was studied by changing the parameters of directional solidification process.The SLM was used to observe the different characteristic regions of the macroscopic reaction. The SEM analysis equipped with EDS was used to study the microstructure of the alloy-formed shell interface and the qualitative analysis of the interfacial reaction product elements. The phase and element valence of the interfacial reaction product were identified by XRD and XPS.The results show that the interface reaction products are mainly HfO₂ and Al_1.98Cr_0.02O₃ and exhibit a sub-regional distribution along the direction of directional solidification.Under the premise of ensuring the directionally solidified alloy structure, lowering the pouring temperature and increasing the withdrawal rate can inhibit the occurrence of delayed interface reaction.

Protection of metal mesh from lightning damage to aviation composite materials

Li LUO, Xiaoya ZHANG, Wenfeng YANG

2020, 40(5): 70-79.

[Abstract](4432) [FullText HTML] (1941) [PDF 1386KB](35)

Abstract:
Carbon / epoxy composites are widely used in aviation due to their high strength, fatigue resistance and corrosion resistance. Aiming at the damage of carbon / epoxy composites during aircraft lightning strikes, a three-dimensional finite element model of carbon / epoxy composite laminates protected by copper mesh and aluminum mesh was established, and the lightning ablative element of composite structure was treated by element deletion method. The lightning protection effect of copper mesh and aluminum mesh was verified under different current peaks and different grid spacing, and the relationship between the weight change of the metal mesh and the lightning protection effect was studied. The test results show that the ablation area and damage depth of the composite laminate with metal mesh protection are significantly reduced. The denser the grid spacing is, the better the lightning protection effect is. The copper mesh composite laminate has better protection effect than the aluminum mesh. With the weight of the metal mesh increases, the degree of lightning damage to the composite laminate decreases.

Hygrothermal mechanical properties of domestic carbon fiber/bismaleimide resin composites for aviation application

Bo LI, Youyi WEN, Qianzu WANG, Yizhuo GU, Min LI, Zuoguang ZHANG

2020, 40(5): 80-87.

[Abstract](3828) [FullText HTML] (2224) [PDF 914KB](44)

Abstract:
The composites were separately prepared by a domestic T700-grade carbon fiber used for aviation and four types of bismaleimide resin. The composite laminates were treated by three hygrothermal conditions, including 100 ℃ boiling water, 70 ℃ water immersion and 70 ℃/85% relative humidity to study the hygrothermal mechanical properties of the composite laminates related to interface and matrix under ambient temperature and 150 ℃. The results show that the moisture absorption decreases the mechanical properties of composites, and the effect on mechanical properties under high temperature is significant. Furthermore, 90^o tensile property, 0^o compressive strength, flexural strength and open-hole compressive strength are sensitive to moisture absorption and temperature, while the sensitivities of 0^o compressive modulus, flexural modulus and open-hole tensile strength are small. By comparing the changes of the mechanical properties of composite after different hygrothermal treatment conditions, it is found that the degree of degradation after 100 ℃ boiling water is larger, which is believed to be related to its higher equilibrium moisture absorption rate. Based on fracture morphology of composite after 90^otensile testing using scanning electron microscope, it is considered that the hygrothermal property of interface is the critical factor to determine the hygrothermal property of domestic carbon fiber composite.

Modal frequency analysis of metallic-ceramic functionally graded plates

Chao LIU, Wenguang LIU

2020, 40(5): 88-95.

[Abstract](3914) [FullText HTML] (2315) [PDF 978KB](17)

Abstract:
Metallic-ceramic functionally graded materials have potential application value in the design of thermal barrier systems for aircraft panels due to their ultrahigh temperature resistant and high strength properties. In this article, the FGMs plate was used as the object to study the influence of parameters such as the volume fraction index, the geometric size of the plate and the thermal environment on the modal frequencies of a FGMs plate. Firstly, the power law distribution function was employed to discuss the influence of thermal environment on the physical properties of FGMs plates. Thereafter, the FGMs linear layered model dependent on temperature field was established by using the temperature continuously changing with the spatial position trait in the finite element, and the validity of this model in dynamic analysis was verified. Finally, the effects of ceramic volume fraction index, FGMs plate length-to-width ratio, temperature gradient and other variables on the modal frequencies of a FGMs plate were comprehensively analyzed and discussed. Results indicate that the higher order modes are mostly impacted by the uniform temperature field, while the linear and nonlinear temperature fields have the greatest impact on the first-order modes. In linear and nonlinear temperature fields, the volume fraction index is the most sensitive one to the effects of modal frequency drop ratio, while the modal frequency drop ratio is mainly affected by the coupling effect of the volume fraction index and the temperature gradient in uniform temperature field.

Optimized processing method of P-S-N curves for high cycle fatigue of aero-engine materials

Wei XU, Xin CHEN, Xudong LI, Bin ZHONG, Yanguang ZHAO, Chunhu TAO

2020, 40(5): 96-103.

[Abstract](3690) [FullText HTML] (2078) [PDF 702KB](46)

Abstract:
High cycle fatigue P-S-N curve of material are important for the design of aero-engine strength. Based on the data processing requirement of the high cycle fatigue of aero-engine materials, a novel data processing method has been developed by proposing the criterion of selecting fitting model and the method for determining the critical stress between the medium and high fatigue cycle regions. Furthermore, the testing data of two common Ti-alloy materials in aero-engine are used to validate the present batch processing method, and the P-S-N curves in various conditions have been obtained. And the comparison of the process time between the present method and the conventional method has been conducted finally. The results show that the present data processing method is suitable not only for the data processing of the traditional high cycle fatigue issues, but also for the data processing of very high cycle fatigue issues. And the efficiency of data processing is significantly improved.

2020 Vol. 40, No. 5