2016 Vol.36(1)

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2016, 36(1): 0-0.
[Abstract](83) [PDF 4669KB](1)
Transition Metal Elements X(X=W,Mo,Cr) Performance Impact Mechanism RuAl Antioxidant Study
Jiang YUAN, Xinhua SONG, Jiayao SUN, Hang GONG
2016, 36(1): 1-6. doi: 10.11868/j.issn.1005-5053.2016.1.001
[Abstract](174) [FullText HTML] (39) [PDF 2584KB](1)
Based on the first-principles density functional theory, the placing in the RuAl alloy and the stability effect of the transition metal elements X(X=W, Mo, Cr) on the structure of the oxides Al2O3and RuO2 were investigated through the calculation of the oxidation energy of the oxides Al2O3 and RuO2 of RuAl alloy.It is found that the oxidation energy of Al2O3 and RuO2 is all increased after the alloying of the transition metal X.The sequence of the size increasing for the Al2O3 oxidation energy is W> Mo> Cr. The sequence of the size increasing for the Al2O3 oxidation energy is Mo> Cr> W. Among them,the best effect for increasing the anti-oxidation capability to the RuAl alloy is W alloying.Simulfaneously,the analysis of statu's density and chargy density indicates that the basic reason for W alloying to increase the RuAl anti-oxidation performance is that the co-valent characteristics between the bonds Al-O/Ru-O are reduced,and the ionic band characteristics between the bonds Al-O/Ru-O are increased.Therefore,the alloying of the metal element X can promote the generation of the existing condition for the inner-oxidation process of RuAl metal oxidation,the continuous and dense Al2O3 oxidation layer is formed on the transverse direction of RuAl surface.
Optimization of Hot Isostatic Pressing Temperature for Cast TiAl Based Alloy with Directional Lamellar Microstructure
Chunlei ZHU, Hongwei WANG, Bo HAN, Xiwen ZHANG, Jianhong YI
2016, 36(1): 7-11. doi: 10.11868/j.issn.1005-5053.2016.1.002
[Abstract](311) [FullText HTML] (66) [PDF 2404KB](6)
The effect of hot isostatic pressing temperature on lamellar breakdown behavior and RT tensile properties was studied for a cast TiAl based alloy with directional lamellar microstructure by conventional casting, in order to optimize the temperature of hot isostatic pressing (HIP) for the special lamellar microstructure. After HIP at 1250℃,excessive equiaxed γ grains were precipitated along the colony boundary or in the colony, which resulted in reduction of tensile strength at RT. After HIP at 1290℃,breakdown of lamellar was occurred by coarsening of lamellar and formation of secondary lamellar with random orientation. Formation of the secondary lamellar resulted in instability of tensile properties at RT. After HIP at 1270℃, less equiaxed γ grains were precipitated and secondary lamellar did not generated, so the better integrality of lamellar and uniformity of lamellar orientation were kept by the microstructure obtained, and also the best tensile properties and good stability were achieved. Finally, HIP at 1270℃ is good for the directional lamellar microstructure.
Die Wear during Backward Extrusion of GH4169 Profiles
Weiwei LI, Xinhong YU
2016, 36(1): 12-17. doi: 10.11868/j.issn.1005-5053.2016.1.003
[Abstract](137) [FullText HTML] (53) [PDF 2193KB](1)
Based on the modified Archard wear model, the effects of process parameters on the die wear during backward extrusion of GH4169 superalloy were systematically analyzed by numerical simulation.The results show that within the experimental data, the most prone wear area of the punch is rounded corner, the maximum wear depth of the die is decreased with the increase of the radius of rounded corner and billet temperature, but increased with the increase of friction factor. Also the maximum wear depth of the die is decreased with the increase of speed when the forming speed is less than 100mm/s, but when the forming speed is more than 100mm/s, the maximum wear depth of the die is increased first and then decreased with the increase of forming speed. When the optimal parameters are the billet temperature of 1020℃, the friction factor of 0.05, the extrusion speed of 100mm/s and the die temperature of 300℃, the wear depth of the die is the smallest, about 9.28×10-3mm.
Hot Deformation Simulation of Spray Formed 7055 Aluminum Alloy
Lingzhuang ZHU, Zhonghua LI, Zhen ZHANG, Xiaojun ZHOU
2016, 36(1): 18-25. doi: 10.11868/j.issn.1005-5053.2016.1.004
[Abstract](207) [FullText HTML] (32) [PDF 2811KB](2)
The hot deformation behavior of spray formed 7055 aluminum alloy was investigated in this paper. Hot compression deformation was performed on Gleeble-3500 thermal-mechanical simulator at strain rate of 0.001-5s-1 and deformation temperature of 573-723K. The result shows that the flow stress of spray formed 7055 aluminum alloy is increased with the increasing of strain rates, while decreased with the increasing of the deforming temperature. The maximum temperature rising induced by deformation heat is 25K during the test at strain rate of 5s-1, and the corrected flow stress is 20MPa higher than measured value. A flow stress constitutive equation is constituted based on Arrhenius hyperbolic sine function containing the Z parameter, and the hot deformation activation energy is 146.91kJ·mol-1. The average absolute relative error (Er) is introduced to evaluate the performance of the developed constitutive equation. The value of Er is 2.89% , which proves the developed constitutive equation can accurately predict the flow stress of the spray formed 7055 aluminum alloy.
Repair Welding of Defects in 2219 Al Alloy Friction Stir Welded Joints
Li ZHOU, Ke HAN, Chaolei LIU, Cheng HUANG, Zhilong CHANG, Huiqiang WU, Jicai FENG, Fanxin MENG
2016, 36(1): 26-32. doi: 10.11868/j.issn.1005-5053.2016.1.005
[Abstract](188) [FullText HTML] (49) [PDF 4719KB](1)
The primary and secondary friction stir repair welding experiments had been untaken for the lack of penetration and cavity of 2219 aluminum alloy joints welded by friction stir welding. The results show that the original defects can be removed with proper welding process parameters and thus we can achieve joints with smooth appearance and good properties. But the area of joint softened zone is increased dramatically by the increase of repair welding times. The tensile properties of primary repaired joints are satisfactory and better than that of secondary repaired for both lack of penetration and cavity defects. In the original joints, fractures all are started in the defects which led to a low ductility. However, after repair, joints fractured show a ductile fracture character at the interface of heat-affected zone and thermal-mechanical affected zone in retreating side.
Microstructure and Properties of AZ91 Magnesium Alloy Prepared by Multi-pass Friction Stir Processing under Different Cooling Conditions
Zhilong LU, Datong ZHANG, Wen ZHANG, Cheng QIU
2016, 36(1): 33-38. doi: 10.11868/j.issn.1005-5053.2016.1.006
[Abstract](355) [FullText HTML] (42) [PDF 2460KB](4)
Multi-pass friction stir processes (MP-FSP)were conducted on cast AZ91 magnesium alloy plate under three different types of cooling condition, including two passes in air, one pass in air and one pass in water, and two passes in water. And microstructure and mechanical properties of the experimental materials were studied.The results show that the second phase, β-Mg17Al12, is changed into particles because of the severe plastic deformation during MP-FSP. Meanwhile, the microstructures in stir zone are refined significantly and the average grain sizes are 5.8 μm, 1.4 μm and 0.8-1 μm respectively. Due to its finer microstructure, the microhardness, tensile strength and elongation of the specimen processed under two passes in water are 94.7 HV, 355.5 MPa and 31.5 %, which are higher than the other two different cooling conditions.
Effects of Surface Deep Rolling treatment on Mechanical Properties and Residual Stress Field in Pure Nickel
Zhuoxiao HUANG, Xiancheng ZHANG, Shandung TU, Yang ZHANG, Yining WANG, Xiayi QIAN
2016, 36(1): 39-47. doi: 10.11868/j.issn.1005-5053.2016.1.007
[Abstract](186) [FullText HTML] (45) [PDF 2728KB](4)
Surface self-nanocrystallization by means of surface deep rolling (SDR) was applied to produce gradient ultra-fine grain structure with the grain size less than 500 nm near the surface of pure Nickel. The subsurface microstructure, residual stress field and mechanical properties of the treated nickel were investigated. It is found that the texture structure is formed near the nickel surface after SDR treatment. Due to severe plastic deformation, a large number of dislocations, dislocation cells and high density-dislocation walls are generated, leading to the formation of ultra-fine grain structure and large compressive stress near the surface. By comparing with the as-received material, the hardness of the material is increased nearly double after SDR treatment. The thickness, hardness, surface roughness of refined layer and residual stress field within it can be adjusted through proper selection of treatment parameters.
Preparation and Microwave Absorbing Properties of La3+ Doped Ni0.35Co0.15Zn0.5Fe2O4 Ferrites
Yong LIU, Yankui CHENG, Yang HU, Guanghu LIU, Xiaohu REN
2016, 36(1): 48-52. doi: 10.11868/j.issn.1005-5053.2016.1.008
[Abstract](155) [FullText HTML] (26) [PDF 1603KB](1)
La3+ doped NiCoZn-ferrite particles were prepared by the sol-gel method, the influence of La3+ content on microstructure, electromagnetic parameters and microwave absorbing properties was studied. Phase structure and microscope image of the sample were investigated by X-ray diffraction and scanning electron microscopy, their static magnetic properties and electromagnetic parameters at 1-12GHz were measured by a vibrating sample magnetometer and vector network analyzer respectively, and the reflection loss was calculated with different thicknesses(3mm, 5mm, 8mm). The results show that doping appropriate amount of La3+ can enhance the microwave absorption of Ni0.35Co0.15Zn0.5Fe2O4-ferrite, and remove the absorbing band to high frequency. When the sample thickness of Ni0.35Co0.15Zn0.5La0.04Fe2O4 mixed with paraffin is 5mm, the minimum reflection loss is -28.4dB, bandwidth (RL≤ -10 dB) is 3.7GHz.
Effect of Nonconductive Inorganic Fillers on Electrical Properties of Epoxy/Graphene Nanoplatelets Composites
Ting CHEN, Tiezheng JI, Huan LIU, Jiaoqiang ZHANG, Xuansheng FENG
2016, 36(1): 53-56. doi: 10.11868/j.issn.1005-5053.2016.1.009
[Abstract](203) [FullText HTML] (42) [PDF 1937KB](2)
Conductive composite based on epoxy(bisphenol A,E-54) filled with graphene nanoplatelets(GNPs,KNG-CZ030) and cured in the presence of 2-ethyl-4-methy imidazole(2,4-EMI) were prepared by solution blending assisted with ultrasonic dispersion.Nonconductive inorganic fillers(NaCl or TiO2) were added as a second filler to study their effects on dispersal uniformity of GNPs and electrical properties of composite.It is found that by adding NaCl and TiO2, the dispersal uniformity of GNPs is improved and the conductivity of composite is increased with reduced room temperature resistivity .When the room temperature resistivity of NaCl/GNPs/E-54 and TiO2/GNPs/E-54 composites is 106Ω·m,their mass fractions are 0.75% and 0.72% respectively,which are lower than 0.97%,the mass fraction of GNPs/E-54 composite without adding inorganic particles.
Influence of Weight Ratio of Ball-to-Powder on Flake-Shaped Process and Electromagnetic Properties of Carbonyl Iron Powders
Liying ZHAO, Pingan LIU
2016, 36(1): 57-61. doi: 10.11868/j.issn.1005-5053.2016.1.010
[Abstract](171) [FullText HTML] (41) [PDF 1879KB](3)
The flake-shaped carbonyl iron powder(FCIP) was prepared by wet ball mill method with ethanol as isolation agent(0.1 nm). The influence of the ratio of ball to powder on the flake-shaped process and electromagnetic parameter was studied. The results show that the grain size of FCIP gradually is decreased and the anisotropy is increased significantly with the enhancing of the ratio of ball to powder. The dielectric loss and magnetic loss microwave performance are enhanced significantly attributed to the anisotropy of the FCIP. Epoxy resin is applied as bonders. The single-layer microwave absorbing coating with 1.0 mm in thickness is prepared by using epoxy resin as a matrix and the FCIP with the volume fraction of 30%. The lightest coating weights 2.96 kg/m2, when it meets the request of band width more than 10 GHz, and the reflectivity is less than -7.5 dB at the frequency range of 8-18 GHz.
Periodic Reversal Pulse Fast Electrodeposition of Al2O3/Ni Composite Coatings
Jutian CHEN, Jingyin FEI, Fangfang SHI, Bei LI, Yan ZHANG
2016, 36(1): 62-68. doi: 10.11868/j.issn.1005-5053.2016.1.011
[Abstract](144) [FullText HTML] (41) [PDF 3005KB](1)
Based on Al2O3 particles as dispersed phase, the Al2O3/Ni composite coating was prepared by the method of periodic reversal pulse fast electrode position. The micro morphology and the composition of Al2O3/Ni composite coating were characterized by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The effect of the pulse parameters on the Al2O3 content in the composite coating and coating's micro morphology ware investigated. Also the comparison between the micro morphology, coating's stress and deposition rate of the composite coating deposited by periodic reversal pulse electrode position and direct current electrode position was undertaken. The results show that the Al2O3/Ni composite coating with fine grains, low inner stress and high deposition rate was obtained by periodic reversal pulse electrode position.
Impact of Curing Pressure on Peel Strength of Hot-curing Metal/rubber Adhesive Joint
Peng WANG, Zhengtao SU, Liangqing LAI, Lei XUE, Linzhao FENG, Jinghe WANG
2016, 36(1): 69-74. doi: 10.11868/j.issn.1005-5053.2016.1.012
[Abstract](244) [FullText HTML] (48) [PDF 1554KB](1)
The physical and mechanical properties of nature rubber compound vulcanized (NR1155) under different curing pressures were studied, such as 6MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa. The peel strength of adhesive joint in metal/rubber composite structures, vulcanized under different curing pressures, were tested based on standard test methods of the adhesion between vulcanized rubber and rigid substrates. Meanwhile, the cross densities of rubber part in metal/rubber composite structure were studied by rubber cross-linking density measuring instrument (Low-dimensional NMR). Also, the topography of peeled surfaces was investigated by SEM. The results indicate that NR1155 and chemlok 205/chemlok 220 adhesive present excellent compatibility and well co-curing synergy effect. In addition, the peel strength of adhesive joint firstly increased and then decreased with the increasing of curing pressure, as well as that largest peel force (F) present well functional dependency to curing pressures, but the cross densities of vulcanized rubber present opposite trend.
Effects of Epoxy Resin Cross-Linked Structure Characteristics on Longitudinal Compressive Performance of Carbon Fiber Reinforced Composites
Wei LIU, Tianjiao ZHANG, Jianwen BAO, Daijun ZHANG, Xiangyu ZHONG, Weidong LI, Ye LIU
2016, 36(1): 75-80. doi: 10.11868/j.issn.1005-5053.2016.1.013
[Abstract](193) [FullText HTML] (37) [PDF 2107KB](1)
The epoxy resin matrix with different cross-linked structure was obtained by changing the ratio of the resin with different degree of functionality. The effects of epoxy resin with different cross-linked structure characteristics on longitudinal compressive performance of domestic made T800 carbon fiber reinforced composites were studied in this paper. The results show that, with the content of the trifunctional epoxy resin increasing, the crosslinking density of resin matrix is increased, the modulus of resin matrix is increased, and the Poisson's ratio of unidirectional carbon fiber composites laminates is decreased too. It is found that the longitudinal compressive strength of carbon fiber composites is increased with the resin matrix crosslinking density increasing. The effect of crosslinking density of resin matrix on the compressive modulus of unidirectional composite laminates is not obvious.
Obtaining Uniaxial Constitutive Relationships of Ductile Materials by Using Small-scale Notched Bending Specimens
Tao YIN, Lixun CAI, Hui CHEN, Chen BAO
2016, 36(1): 81-86. doi: 10.11868/j.issn.1005-5053.2016.1.014
[Abstract](203) [FullText HTML] (38) [PDF 2157KB](1)
A test method is proposed to obtain uniaxial constitutive relationships of ductile materials by using the small-scale bending specimens with a semi-circle notch. Linear load-displacement experimental curves of the specimens under three-point bending tests are taken as the iterative referenced target so that RVE (Representative volume element) uniaxial constitutive relationships of the ductile materials are obtained by the FAT (Finite-element-analysis aided tests) method. It is shown that the uniaxial constitutive relationships for two kinds of ductile materials by finite-element-analysis are in good agreement with the standard tensile results. Therefore, the method for the small-scale specimens can be conveniently used to get the uniaxial constitutive relationships for ductile materials.
High-cycle Fatigue Behavior of TiAl Alloy Containing Preferentially Oriented Lamellar Microstructures
Wenjuan WAN, Bo HAN, Wei HAN, Ji ZHANG
2016, 36(1): 87-92. doi: 10.11868/j.issn.1005-5053.2016.1.015
[Abstract](155) [FullText HTML] (28) [PDF 2824KB](1)
The high-cycle fatigue performance of Ti-47.5Al-2.5V-1.0Cr-0.2Zr (at.%) alloy with a preferentially oriented lamellar microstructure has been evaluated by means of load-controlled rotating bending fatigue tests at elevated temperature, and fracture surfaces of fatigue specimens were also analyzed by scanning electron microscope. The results show that it exhibits a flat S-N curve fitted by Basquin equation, and its fatigue limit is equal to 60% of the ultimate tensile strength at 750℃. The fracture surface observation proves that all of the fatigue crack propagation in the studied samples is indeed presented with a typical translamellar mode, and indicating the high resistance of this microstructure to crack propagation.
Low-cycle Fatigue of Directionally Solidified Superalloy DZ408
Shichao ZHANG
2016, 36(1): 93-97. doi: 10.11868/j.issn.1005-5053.2016.1.016
[Abstract](172) [FullText HTML] (36) [PDF 1817KB](3)
The total strain-controlled low cycle fatigue(LCF) behaviors of directionally solidified(DS) superalloy DZ408 at 950℃,1000℃ and 1050℃ for R=0.05 were investigated. The results of LCF tests indicate that the mean stress relaxation is occurred under asymmetric straining . The rate of mean stress relaxation is increased with the increase of temperature and strain amplitude. The alloy has Massing characteristic at 950℃,1000℃ and 1050℃ for R=0.05. All the LCF data obtained under various temperatures are well correlated by the modified SWT approach for lifetime prediction, and also the relationship between temperature and parameter of modified SWT model are obtained.

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