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2022 Vol. 27, No. 4
Published: 2022-08-15
Engineering and Technology
Theoretical Research
Theoretical Research
345
Ab initio molecular dynamics study on eutectic Ga-Sn and 10Li-GaSn
DING An, WANG Jianchuan
DOI: 10.19976/j.cnki.43-1448/TF.2022014
The eutectic Ga
91.6S
n
8.4
liquid metal can be served as the anode in Li-ion batteries. In this paper, the structure and kinetic properties of Ga
91.6
Sn
8.4
and Ga
91.6
Sn
8.4
with 10% (mole fraction, %, the same below) lithium intercalation (10Li-Ga
91.6
Sn
8.4
) were compared and analyzed by ab initio molecular dynamics. Calculation results show that there is no obvious differences in liquid structure between Ga
91.6
Sn
8.4
and 10Li-Ga
91.6
Sn
8.4
, both of them exhibit short-range order. The introduction of Li induces the second peak of the radial distribution function of 10Li-Ga
91.6
Sn
8.4
appear “split”, indicating that the order of the system increases and the melting points increases. In 10 Li-Ga
91.6
Sn
8.4
, the intercalation of Li reduces the diffusion coefficient of each atom in the system, and the attraction between Li-Sn atoms is significantly stronger than that of Li-Ga. Therefore, during the charging process, the Ga
91.6
Sn
8.4
Li-ion liquid metal battery exhibits the tendency of liquid-to-solid transition.
2022 Vol. 27 (4): 345-350 [
Abstract
] (
1429
)
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(1 KB)
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900
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351
Experimental determination and thermodynamic assessment of the Zr-Cr-Y ternary system
QIAO Hui, HU Biao, ZENG Gang, JIN Chenggang, GAO Jian
DOI: 10.19976/j.cnki.43-1448/TF.2022028
The phase equilibria of the Zr-Cr-Y system was investigated by combination of key experiments and CALPHAD (calculation of phase diagrams) methods. Eight ternary alloys were prepared to determine the isothermal sections of the Zr-Cr-Y system at 1 000, 900, 800 and 600 ℃ by means of X-ray diffraction (XRD) and scanning electron microscope with energy dispersive X-ray spectroscopy (SEM/EDS). The results show that there are three-phase regions, i.e., BCC(Cr)+HCP(Y)+αCr
2
Zr, BCC(Zr)+HCP(Y)+αCr
2
Zr and HCP(Zr)+HCP(Y)+αCr
2
Zr in this system. Based on the experimental equilibria data obtained in the present work, thermodynamic modeling of the Zr-Cr-Y ternary system was performed by the CALPHAD method. A set of accurate thermodynamic parameters of the Zr-Cr-Y system were obtained. The calculated results are in good agreement with most of the reliable experimental data.
2022 Vol. 27 (4): 351-359 [
Abstract
] (
668
)
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730
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360
Thermodynamic optimization and calculation of the Al
2
O
3
-MgO and Al
2
O
3
-MgO-SiO
2
systems
MA Tianyi, LIU Yuling, GAO Fengyang, ZHANG Liang, DU Yong
DOI: 10.19976/j.cnki.43-1448/TF.2022034
Since the thermodynamic parameters of Al
2
O
3
-MgO binary system in the reported literatures deviated from the experimental data when it was extrapolated to the multivariate system, the calculation of phase diagram (CALPHAD) method was used in this work to re-optimize the system based on the rigorous evaluation of the thermodynamic data. Subsequently, the thermodynamic description of the Al
2
O
3
-MgO-SiO
2
system was further improved. In the optimization process, the ionic two-sublattice model was used to describe the liquid phase and compound energy formalism (CEF) model was used to describe the solid phase. The results of thermodynamic optimization and calculation of Al
2
O
3
-MgO and Al
2
O
3
-MgO-SiO
2
phase diagrams are in good agreement with most experimental data. This work is the basis of constructing a thermodynamic database of Al
2
O
3
-SiO
2
-MgO-CaO-Fe
2
O
3
-Na
2
O system, and can provide guidance for the high-value utilization of bulk aluminosilicate solid waste.
2022 Vol. 27 (4): 360-371 [
Abstract
] (
675
)
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3481
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Engineering and Technology
372
Effects of temperature on microstructure and mechanical properties of Mg-6Zn-
x
Mn alloy prepared by semi-solid powder moulding
YANG Shanghui, LUO Xia, LI Mingyu, LIU Jiaxing, LÜ Chunyang, HUANG Jing, BAO Feifei, HUANG Bensheng
DOI: 10.19976/j.cnki.43-1448/TF.2022050
Using metal magnesium, zinc, manganese powders as raw materials, Mg-6Zn-
x
Mn (
x
=0.5%, 1.0%) magnesium alloys were prepared at a temperature of 540-600 ℃ by semi-solid powder moulding method. The effects of forming temperature on the microstructures (phase and grain size), mechanical properties (compressive strength and microhardness), and corrosion resistance of the alloys were investigated by means of optical microscope, X-ray diffractometer, scanning electron microscope, microhardness tester, universal testing machine, and electrochemical test. The results show that with the increase of forming temperature, the relative density and average grain size increase, while the microhardness and compressive strength decrease. With the forming temperature increasing from 540 ℃ to 600 ℃, the compressive strength of Mg-6Zn-0.5Mn and Mg-6Zn-1.0Mn alloys decreases from 382.8 MPa and 372.1 MPa to 348.9 MPa and 353.1 MPa (decreasing by about 8.9% and 5.4%, respectively), mainly as the forming temperature increases, more oxide inclusions are generated at the grain boundaries, thereby reducing the compressive strength of the alloy. The microhardness (HV) of the alloys is above 95.1, and Mg-6Zn-0.5/1.0Mn alloy prepared at 600 ℃ has the lowest degradation rate of 0.263 mm/a and 0.183 mm/a, respectively.
2022 Vol. 27 (4): 372-381 [
Abstract
] (
647
)
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(1 KB)
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(1104 KB) (
863
)
382
Computational meso-mechanical model and mechanical property of short carbon fiber reinforced copper matrix composites
HE Donglang, FANG Huachan, LI Yuxing, LI Jinwei
DOI: 10.19976/j.cnki.43-1448/TF.2022016
For the short carbon fiber reinforced copper matrix composites (C
Sf
/Cu) prepared by powder metallurgy, a model was established to analyze the tensile damage evolution, fracture mechanical behavior and the influence of weak interface on mechanical properties of composites. The results show that the composites can be divided into elastic stage, plastic hardening stage, damage initiation stage, and damage evolution stage. The stress concentration at the fiber end causes the debonding of the end interface, the damage evolution of the axial interface and the fiber bridging. The damage of the matrix and the accompanying interface are the main fracture mechanism of the material. When the fiber length is greater than 60 μm, the axial stress of the fiber presents a “w” shape, and the fiber has a strong bearing capacity. When the fiber length is 20 μm, the fiber has almost no bearing capacity. The higher the load on the fiber, the easier it is to cause interfacial damage. With increasing fiber length from 20 μm to 140 μm, the strength of the composite decreases from 146 MPa to 102 MPa.
2022 Vol. 27 (4): 382-388 [
Abstract
] (
720
)
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(1 KB)
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(625 KB) (
1493
)
389
Influence of densification temperature and interface type on the structure and mechanical properties of SiC
f
/SiC Mini composites
WANG Duo, CHEN Zhaoke, HE Zongbei, ZHANG Ruiqian, XIONG Xiang
DOI: 10.19976/j.cnki.43-1448/TF.2022010
Pyrolytic carbon (PyC) interface and (PyC/SiC)
3
multi-layer interfaces were introduced into SiC fiber bundles by chemical vapour infiltration (CVI). After densification of SiC matrix in SiC fiber bundles containing PyC interface at 1 050 ℃ and 1 250 ℃, and in SiC fiber bundles containing (PyC/SiC)
3
multilayer interface at 1 050 ℃, SiC
f
/SiC Mini composites with different interface types and different matrix structures were obtained. The microstructure and tensile fracture behavior of the as-prepared SiC
f
/SiC minicomposites were studied. The results show that a clear interface with the thickness of about 300 nm is introduced successfully between the inner fiber and the SiC matrix. After densification at 1 050 ℃, the tensile strength of the SiC
f
/SiC Mini composite with PyC interface is 174 MPa, with the debonding mainly occurring between the SiC matrix and the interface. While the tensile strength of SiC
f
/SiC Mini composites with (PyC/SiC)
3
multilayer interface reaches 540 MPa, with the debonding mainly occurring between the sublayer of the multilayer. As the densification temperature increases, the SiC matrix of the SiC
f
/SiC Mini composites changes from fine, porous needle-like to coarse, dense lamellar, with the grain size and crystallinity increaseing significantly. The tensile strength of the composites obtained at 1 250 ℃ is 309 MPa, showing typical brittle fracture characteristics.
2022 Vol. 27 (4): 389-397 [
Abstract
] (
667
)
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1131
)
398
Effects of single-stage aging treatment on microstructure, mechanical properties and corrosion properties of 2A97 Al-Li alloys
YOU Renxuan, MA Yunzhu, TANG Ya, ZHAO Xinyue, LIU Wensheng
DOI: 10.19976/j.cnki.43-1448/TF.2022030
In order to determine the effects of single-stage aging regime on the microstructures, mechanical properties and corrosion properties of 2A97 Al-Li alloys, the methods of room temperature tensile, intergranular corrosion, exfoliation corrosion, electrochemical corrosion and TEM observation were used to investigate the microstructure, mechanical properties and corrosion properties of 2A97 Al-Li alloys after different single-stage aging treatments. The alloys were tested and characterized. The results show that with increasing the aging temperature, the aging time for 2A97 Al-Li alloys to obtain the best mechanical properties decreases. With increasing the aging temperature and aging time, the corrosion resistance of the alloys decreases. After aging at 165 ℃ for 60 h, the tensile strength, yield strength and elongation of the alloys are 549 MPa, 484 MPa, and 8.8%, respectively, the intergranular corrosion is grade 4, and the exfoliation corrosion grade is EC.
2022 Vol. 27 (4): 398-408 [
Abstract
] (
815
)
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(1 KB)
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(1961 KB) (
1554
)
409
Deposition characteristics and wear mechanism of CuCrZr electromagnetic launch rail
LI Yuxing, YAO Pingping, LI Zhuan, ZHOU Haibin, WANG Xing, ZHAO Yibo, KANG Li, DENG Minwen
DOI: 10.19976/j.cnki.43-1448/TF.2022023
The dismantling study on the CuCrZr alloy orbital after the electromagnetic emission experiment was carried out. Combined with canning electron microscopy (SEM), energy X-ray spectroscopy (EDS), X-ray diffraction (XRD), photoelectron spectroscopy (XPS) and electron backscatter diffraction (EBSD) etc., the surface of the orbital surface in four regions along the emission direction was analyzed. The deposition characteristics and wear mechanism were studied. The results show that most of the rail surface is covered by deposition. The thickness of the deposition layer tends to be thin to thick, and then to thin again in the second half of rail, and the thickest position reaches 65 μm. The main components of the deposition are Cu, Al, Al
2
O
3
and Al
4
Cu
9
, etc. There are some typical features in the deposition layer, including spalling, grooving, water-like structure, surface-attached wear debris, pores, packed pores and cellular-dendrites, which shows a mixed state of mechanical and electrical wear. The characteristics of the deposition layer in different regions are obviously different, including thickness, size and number of pores, microstructure inside the deposition, cracks, surface morphologies, etc. Diffusion occures at the interface between the deposition layer and the rail, forming a diffusion interface. And the grain orientation of the deposition layer is perpendicular to the rail surface.
2022 Vol. 27 (4): 409-418 [
Abstract
] (
827
)
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981
)
419
Superplastic deformation behavior of hot isostatic pressed Ti-45Al-7Nb-0.3W hot-rolled alloy sheet
PENG Yuqin, LI Yingxin, LIANG Xiaopeng, LI Huizhong, CHE Yixuan, GUO Xinming
DOI: 10.19976/j.cnki.43-1448/TF.2022044
The hot isostatic pressed (HIP) Ti-45Al-7Nb-0.3W alloy sheet prepared by hot-rolled at 1 270 ℃, and the microstructure of the alloy sheet was investigated by scanning electron microscopy (SEM). High-temperature tensile experiments at 950 ℃ with an initial strain rate of 1×10
-4
s
-1
were performed. According to the tensile stress-strain curve and tensile properties, as well as the microstructure evolution and tensile fracture morphology after tensile fracture, the superplastic deformation (SPF) behavior of the alloy sheet with rolling deformation was studied. The results show that after rolling, the microstructure of as-HIPed alloy sheet changes from near-γ microstructure to duplex microstructure. And the average grain size of the sheet decreases and the elongation increases with the increase of rolling reductions. When the rolling reduction is 61%, the average grain size of the hot-rolled sheet is the smallest (9.8 μm), the elongation of the sheet is the largest (367.5%), and the tensile strength is 131 MPa. Continue to increase the rolling deformation, the grain size of the sheet grows, and the elongation decreases. During the SPF, the α
2
/γ lamellar colonies rotate and decompose, and a large number of dynamically recrystallized (DRX) grains are generated around them. The superplastic mechanism of the plates is grain boundary slip (GBS) and DRX.
2022 Vol. 27 (4): 419-425 [
Abstract
] (
513
)
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(1 KB)
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(898 KB) (
887
)
426
Preparation and characterization of nanocrystalline TaZr
2.75
C
3.75
solid solution ceramic powder
JANG Jie, YI Maozhong, ZHOU Yuanming, PENG Ke
DOI: 10.19976/j.cnki.43-1448/TF.2022019
Single-phase solid solution ceramic powders TaZr
2.75
C
3.75
were synthesized by combining solvothermal and carbothermal reduction. In which, TaCl
5
and ZrCl
4
were used as the tantalum and zirconium source respectively and phenolic resin was used as the carbon source. The possibility of the synthesis of TaZr
2.75
C
3.75
powders by the carbothermal reduction method was demonstrated by thermodynamic and atomic size effect. The effects of process parameters such as acetylacetone content, metal atom concentration and solvent type on the powder morphology and particle size were investigated. The results show that the single-phase TaZr
2.75
C
3.75
solid solution ceramic powders can be prepared by the carbothermal reduction reaction at 1 700 ℃. Increasing the content of acetylacetone can improve the dispersibility of the powders. With increasing the concentration of metal atoms, the powder changes from a spherical shape to an irregular shape, and the average particle size decreases from the micron level (~2.13 µm) to the submicron level (~0.140 µm). Compared witn butanol solvent, better dispersion and smaller particle size of TaZr
2.75
C
3.75
solid solution ceramic powders can be achieved with ethanol as a solvent.
2022 Vol. 27 (4): 426-435 [
Abstract
] (
642
)
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(1 KB)
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(952 KB) (
1580
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436
Microstructure and thermal conductivity property of U
3
Si
2
fuel pellets by vacuum sintering
LU Yonghong, JIA Daikun, SU Danke, PAN Xiaoqiang, XIA Jibin, WANG Yifan, WANG Ting, ZHANG Xiang, WANG Zizhen, QIUShaoyu
DOI: 10.19976/j.cnki.43-1448/TF.2022064
Using U
3
Si
2
powder as raw material, U
3
Si
2
fuel pellets were prepared by vacuum sintering method. The effect of sintering temperature on the density of U
3
Si
2
pellets was studied. The uranium concentration and impurity content of U
3
Si
2
fuel pellets were also revealed. The microstructure and thermal conductivity property of U
3
Si
2
fuel pellets were then characterized. The results show that the density of U
3
Si
2
fuel pellets first increases and then decreases with the increase of sintering temperature. The U
3
Si
2
fuel pellets sintered at 1 550 ℃ for 2 h possesses the highest relative density, which is about 96.7%. And the uranium mass concentration of the pellets is 10.81 g/cm
3
, significantly higher than the uranium mass concentration of the active UO
2
pellets. The U
3
Si
2
fuel pellet is composed of U
3
Si
2
, USi and UO
2
phases. The thermal diffusivity of the pellet increases gradually with the increase of temperature. The thermal diffusivity at 500 ℃ is 3.95 mm
2
/s, which is about two times higher than that of the UO
2
pellet.
2022 Vol. 27 (4): 436-441 [
Abstract
] (
696
)
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(451 KB) (
1399
)
442
Microwave absorbing properties of 3D printed carbonyl powder/polydimethylsiloxane flexible composite
ZHANG Xueting, ZHOU Yi, XIAO Wei, TIAN Zhaoxia, LIU Fenghua
DOI: 10.19976/j.cnki.43-1448/TF.2022025
The printing ink was prepared by mixing flake carbonyl iron powder (FCI) and spherical carbonyl iron powder (SCI) with polydimethylsiloxane (PDMS), respectively. The carbonyl iron powder/polydimethylsiloxane (CIP/PDMS) flexible composite microwave absorbing material was formed by 3D printing with ink direct writing. The effects of the morphology and content of carbonyl iron powder (CIP) on the rheological behavior of ink and 3D direct writing printing process were studied. The electromagnetic reflection loss of CIP/PDMS composite microwave absorbing material was studied as well by CST Studio Suite electromagnetic simulation software. The results show that the higher the CIP content, the better the microwave absorption performance of the composite. When
w
(FCI) is 30%, the FCI/PDMS composite has the best microwave absorption performance. When the thickness is 1.8 mm, it has the strongest absorption peak for the electromagnetic wave with frequency of 10.9 GHz, the peak value is -34.8 dB, and the effective absorption bandwidth (EAB, RL<-10 dB) is 4.8 GHz. When
w
(SCI) is 80%, SCI/PDMS composite has the best microwave absorption performance. When the thickness is 2.4 mm, it has the strongest absorption peak for electromagnetic wave with frequency of 7.3 GHz, the peak is -41.5 dB and EAB is 3.6 GHz.
2022 Vol. 27 (4): 442-452 [
Abstract
] (
869
)
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(1 KB)
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(1241 KB) (
2046
)
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