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Chen S.-Q.,Zhangjiajie Institute of Aeronautical Engineering | Chen S.-Q.,Central South University | Song X.-H.,Zhangjiajie Institute of Aeronautical Engineering | Chen L.,Zhangjiajie Institute of Aeronautical Engineering
Chinese Rare Earths | Year: 2017

The present work investigates the influences of Sm on mechanical and corrosion properties of magnesium alloys. Casting state and extruded state organizations of Mg-3Zn-xSm alloys were observed through optical microscope (OM) and scanning electron microscope (SEM). Electrochemical properties of alloys were tested through electrochemical workstation. The results show that as-cast microstructure is significantly refined gradually with increasing Sm content, where the space of dendrite decreases obviously. The constituent phase Mg-Zn-Gd ternary phase area fraction gradually increases, second phase tends to distribute from continuous reticulation along grain boundary to interrupted distributions along grain boundary and uniform distribution in the grain. Microstructure after extrusion is obvious refined, the average grain size decreases from 18 μm of Mg-3Zn-0.5Sm to 18μm of Mg-3Zn-4Sm. σb, σ0.2 and δ of tensile mechanical properties of the extruded Mg-3Zn-0.5Sm alloy increases from 225 MPa, 146 MPa and 15% to 250 MPa, 195 MPa and 25%. σb, σ0.2 and δ are accordingly increased by 11.1%, 33.6% and 66.7%. With the increase of content of Sm, the corrosion current density decreases and high-frequency capacitance is gradually increasing, the addition of Sm improves the corrosion resistance of Mg-Zn-xSm alloy. © 2017, Editorial Office of "Chinese Rare Earths". All right reserved.


Xu Z.,Zhangjiajie Institute of Aeronautical Engineering | Song H.,Hunan University
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2011

The interaction between a screw dislocation dipole and an interfacial blunt crack is dealt with in this paper. Utilizing the conformal mapping technique, the closed-form solutions are derived for complex potentials and stress fields due to a screw dislocation dipole located near the interfacial blunt crack. The stress intensity factor on the crack tip and the critical stress intensity factor for dislocation dipole emission are also calculated. The influence of the orientation and length of the dislocation dipole and the morphology of the blunt crack as well as the material elastic dissimilarity on the shielding effect and the emission criterion is discussed in detail. The results show that screw dislocation dipole can reduce the stress intensity factor of the interfacial blunt crack tip (shielding effect) only when the screw dislocation located in certain region. The shielding effect increases with the increase of the length of the dipole. The critical loads at infinity for dislocation dipole emission increases with the increase of emission angle and the curvature radius of the blunt crack, and the most probable angle for screw dislocation dipole emission is zero. The dislocation dipole emission is more difficult than the single dislocation emission. The present solutions contain previous results as special cases.


Xia L.,Zhangjiajie Institute of Aeronautical Engineering | Zhu S.,Zhangjiajie Institute of Aeronautical Engineering | Zhu S.,Hunan University
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2013

With the rapid development of fuel cell and fuel cell electric vehicle, LiBH4 was considered to be one of the most promising materials for hydrogen storage. However, the high sorption, desorption temperature and slow sorption kinetics limited their practical applications. In order to improve the performance of LiBH4, a small amount of Al was dissolved into LiBH4 . A first-principles plane-wave pseudopotential method based on the density functional theory was used to calculate negative formation heat, dissociation energy of H atom, the crystal and electronic structure and stability of LiBH4-Al system. The calculation results of negative formation heat and dissociation energy of H atom showed that after the Al was alloyed, the structural stability deteriorated, the heat absorbed diminished in the process of dehydrogenation, dissociation energy of H atom reduced, dehydrogenating properties of the system were improved. After analyzing the densities of states (DOS), Mulliken populations and the charge distribution, it was found that the B-H bond was covalent, the violent formation of which was one of the reasons for difficult dehydrogenation of LiBH4. The role of Al alloy in improving LiBH4 dehydrogenation solution was mainly because Al caused the energy gap near the Fermi level to change and Li-BH, B-H bonding declined in the LiBH4 system. The results matched well with the actual situation, which could provide a theoretical guide to practical applications for LiBH4 because it revealed the microscopic mechanism of dehydrogenation with Al addition in LiBH4 system.


Xia L.,Zhangjiajie Institute of Aeronautical Engineering | Zhu S.,Zhangjiajie Institute of Aeronautical Engineering | Zhu S.,Hunan University
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2014

Hydrogen, which has the characteristics of clean, efficient and renewable utilization, was one of the promising new energies in the future. The safe, efficient and economical hydrogen storage was the key technique for the large scale application of hydrogen energy, relative to the high pressure gaseous hydrogen storage and liquid hydrogen storage, the solid state hydrogen storage technology could store hydrogen in materials by forming solid solution or hydrides, which was regarded as the most promising technique because of its good safety and high energy density. LiBH4 was the typical representative of high capacity of hydrogen storage material and research hot spot because of its theory capacity of 18.5%(mass fraction), far from overtaking hydrogen source system load weight greater than 5% of hydrogen storage capacity requirements, but it was faced with serious thermodynamics and kinetics problems. Starting from improving performance of the absorption and releasing LiBH4 hydrogen, the research progress of hydrogen storage technology and hydrogen storage material was analyzed, and the major measures taken in recent years were reviewed, such as adding reactants to form a composite hydrogen storage system, the appropriate doping anion and cation to change the electronegativity, adding catalyst, reducing the grain size and nanometer filling method. The emphases were focused on the mechanisms, hydrogen storage capacity, temperature and condition thermodynamics and kinetics. High capacity LiBH4 hydrogen storage materials were the key to practical onboard hydrogen source system, the focus of future research was to develop method and system of quick hydrogen absorption, a large amount and reversibility of hydrogen absorption and desorption, and room temperature operation.


Luo Q.,Lianyuan Iron and Steel Co. | Lu D.,Zhangjiajie Institute of Aeronautical Engineering | Luo J.,Chongqing University
Advanced Materials Research | Year: 2010

In this paper, a new welding experiment is studied by applying an additional longitudinal electromagnetic field to CO2 welding process (abbr. LEM-CO2 welding).The characteristics of droplet transfer, macrostructure and microstructure are compared between LEM- CO2 welding and general CO2 welding on Q235 low carbon steel thick plate joint. The research results shows that, an additional longitudinal magnetic field can have a significant effect on properties of the droplet transfer in CO2 welding, the frequency and stability of the droplet transfer in LEM-CO2 welding are improved. The grains of welding seam are refined and welding joints has a higher quality. So the additional longitudinal magnetic field is a very simple and effective method to improve the properties of CO2 welding thick plate joint. © (2010) Trans Tech Publications.


Xie H.,Zhangjiajie Institute of Aeronautical Engineering | Lei L.,Xinyang Normal University
Open Cybernetics and Systemics Journal | Year: 2015

At present, more and more data are expressed in the form of XML format, how to manage these data efficiently becomes an important issue. To solve the problems of large encoded data storage space, data update and low query efficiency, we propose a new encoding scheme named SDUE (Supporting Data Update Efficiently). We tried to decompose the encoding node location information, avoiding recording redundant information, thus effectively saves storage space; moreover, SDUE also effectively support data updates. In the area of query, since record-taking point SDUE path information encoded in the path of the query, which avoided the structural join operations, query efficiency has been improved efficiently. Experimental results show that compared with other coding, SDUE coded has obvious advantages such as storage space utilization, efficiency query and nodes update speed. © Xie and Lei.


Chen S.,Aerospace Research Institute of Materials And Processing Technology | Chen S.,Zhangjiajie Institute of Aeronautical Engineering | Chen L.,Zhangjiajie Institute of Aeronautical Engineering | Song X.,Zhangjiajie Institute of Aeronautical Engineering
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2015

The orthogonal experiment was designed for heat treatment of ZL102 aluminum alloy. Combined with the tensile strength test, range analysis and variance analysis of orthogonal results were carried out. The desirable heat treatment parameters for aluminum alloy were presented as follows: solid solution treatment at 500℃ for 7 h and aging treatment at 220℃ for 3 h. Effects of heat treatment on mechanical properties of ZL102 alloys were investigated by wheatstone bridge conductivity measurement, optical microscope and scanning electron microscope. The results indicate that, tensile strength and hardness of ZL102 are improved dramatically after heat treatment, and conductivity can also be improved. Consequently, the heat treatment system is feasible. ©, 2015, Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys. All right reserved.


Chen L.,Zhangjiajie Institute of Aeronautical Engineering | Huang H.,Central South University | Yang Z.,Central South University | Hou D.,Zhangjiajie Institute of Aeronautical Engineering | Song X.,Zhangjiajie Institute of Aeronautical Engineering
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2015

thixoforging process of A356/A390 alloy composites at semi-solid state was simulated by finite element software, and filling of bimetal in the compound forming process was visualized to under-stand effects of forging speed and friction coefficient on compound forming. The results reveal that filling of the dissimilar materials exhibits independent relatively with low loading. Particles in compound interface is subjected to not only shear deformation but also stable pressure. When the forging speed is slow, temperature and stress of composite interface billets become uneven gradually, which leads to compound interface line closed to bottom surface of the middle of the parts slightly. When the forging speed is fast, compound interface line is closed to top surface of the middle of the parts seriously, which leads to the filling un-complete at bottom of the parts. With the forging speed of top die of 120 mm/s, temperature and stress of composite interface billets exhibit uniform relatively, and billets is filled fully, so compound interface line demonstates straight at the middle. ©, 2015, Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys. All right reserved.


Chen S.,Guangdong Institute of Materials and Processing | Chen S.,Zhangjiajie Institute of Aeronautical Engineering | Zheng K.,Guangdong Institute of Materials and Processing | Wang H.,Guangdong Institute of Materials and Processing
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2016

Failure behavior of semi-autogenous mill liner was analyzed under V-Ti-magnetite wet grinding conditions. Through the optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), hardness tester and other materials testing instruments, the microstructures of failure liner were investigated, and the corrosive wear mechanism of liner material under weak alkaline conditions was expounded. The results show that the surface of liner is mainly characterized by cutting furrow, corrosion pits and cracks. The interaction of low surface hardness, weak hardening effect and corrosion-wear of liner material are responsible for failure of liner. © 2016, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.

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