Showing papers in "Acta Metallurgica Sinica (english Letters) in 2010"
TL;DR: In this paper, the effect of process parameters of pulsed current tungsten inert gas welding on weld pool geometry of titanium welds was investigated and the results showed that pulsed currents and inert gas welds are more stable with respect to the weld parameters.
Abstract: Effect of process parameters of pulsed current tungsten inert gas welding on weld pool geometry of titanium welds M. Balasubramanian ∗ Department of Mechanical Engineering, Velammal Engineering College, Surapet, Anna University, Guindy, Chennai 600 025, Tamilnadu, India V. Jayabalan Department of Manufacturing Engineering, Anna University, Guindy, Chennai 600 025, Tamilnadu, India V. Balasubramanian Centre for Materials Joining & Research, Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar-608 002, Tamilnadu, India Manuscript received 8 July 2009; in revised form 12 April 2010
35 citations
TL;DR: Growth kinetics of titanium boride layers on the surface of Ti6Al4V Fenghua LI as discussed by the authors, Xiaohong YI, Jinglei ZHANG, Zhanguo FAN, Dianting GONG 2) and Zhengping XI 3) 1) School of Material & Metallurgy, Northeastern University, Shenyang 110819, China 2) Vocational Technology College, Liaoning Shihua University, Fushun 113001, China 3) Northwest Institute for Non-ferrous Metal Research, Xi′an 7100
Abstract: Growth kinetics of titanium boride layers on the surface of Ti6Al4V Fenghua LI 1)∗, Xiaohong YI , Jinglei ZHANG , Zhanguo FAN , Dianting GONG 2) and Zhengping XI 3) 1) School of Material & Metallurgy, Northeastern University, Shenyang 110819, China 2) Vocational Technology College, Liaoning Shihua University, Fushun 113001, China 3) Northwest Institute for Non-ferrous Metal Research, Xi′an 710016, China Manuscript received 31 December 2009; in revised form 1 April 2010
25 citations
20 citations
TL;DR: In this article, the electrochemical corrosion behavior of 300M ultra high strength steel in a chloride containing environment was investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM).
Abstract: The electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment was investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that uniform corrosion occurs on 300M steel during the electrochemical measurements because no anodic passivation phenomenon is observed on polarization curves within the measurement range. The tests also show that 300M steel is highly susceptible to chloride containing solution, which is characterized by corrosion current density increasing with the addition of chlorides, and corrosion potential shifting towards positive direction and corrosion resistance decreasing, positively suggesting that chloride ions speed up the corrosion rate of 300M steel. Meanwhile corrosion products on the 300M steel surface formed during the salt spray test are too loose and porous to effectively slow down the corrosion rate. Additionally, a schematic structure of uniform corrosion mechanism can explain that 300M steel has better property of stress corrosion cracking (SCC) resistance than stainless steels.
18 citations
17 citations
12 citations
TL;DR: In this paper, the in∞uence of microstructure on the corrosion behavior of a hotextruded nickel aluminum bronze was studied, and three kinds of samples were prepared and immersion tests in 3.5% NaCl solution were carried out.
Abstract: In this paper, the in∞uence of microstructure on the corrosion behavior of a hotextruded nickel aluminum bronze was studied. Three kinds of samples subjected to the hot-extrusion, annealing and quenching conditions were prepared and immersion tests in 3.5% NaCl solution were carried out. Microstructures and corrosion surface morphologies of the samples were observed by SEM. It was found that the retained fl 0 martensite and (fi+•III) lamella eutectoid in the as hot-extruded material were eliminated after annealing, and corrosion resistance of the alloy was improved. As to the as-quenched material, its corrosion rate was higher than that of the as hotextruded material since the volume fraction of fl 0 phase which was anodic to fi phase increased after quenching. As regards the mechanical properties, the as-quenched sample possesses the highest hardness and tensile strength among the three kinds of samples, while the as-annealed sample possesses the highest elongation. That is to say, heat treatment plays difierent roles in the mechanical properties and corrosion resistance of the experimental alloy.
11 citations
TL;DR: In this paper, the authors showed that the center of foam struts were free of hollows and the Weibull modulus increased signiflcantly due to the decrease of closed porosity.
Abstract: Polymeric sponge replication method is one of the common ways for ceramic foam production. The existence of central triangular voids in the struts results in a decrease of mechanical properties limiting their applications. To remove this defect, some additives consisting of Al powder particles and silica sol are added to ceramic slurries consisting of Al2O3 and ZrO2 (partially stabilized zirconia). With increasing temperature for pyrolyzing and sintering of raw materials, flrst the Al powder and then the glass phase which consisted of melted Al2O3, ZrO2 and SiO2 was soaked into hollow struts. SEM investigations showed that the center of foam struts were free of hollows. XRD considerations depicted that a ZrO2 phase with tetragonal crystallographic structure is present in the produced foam which could be the reason of improved toughness and mechanical properties. Compressive strength of foams increased signiflcantly due to the decrease of closed porosity. The Weibull statistical study showed remarkable increasing of the Weibull module and its value for foams with 10, 20 and 30 ppi was 5.91, 6.06 and 6.53 respectively. KEY WORDS Ceramic foam; Processing; Strut structure; Al2O3-ZrO2; Weibull modulus
9 citations
TL;DR: In this paper, the corrosion behavior of zinc and its alloy under thin electrolyte layers (TEL) in 0.1M NaCl solution was investigated by cathodic polarization curves and EIS.
Abstract: The corrosion behavior of zinc and its alloy under thin electrolyte layers (TEL) in 0.1M NaCl solution was investigated by cathodic polarization curves and EIS. There was only one phase in pure zinc while zinc alloy consisted of eutectic phase and primary phase. Corrosion rate of zinc alloy was faster than that of pure zinc due to the effect of the micro-galvanic couples between the primary phase and the eutectic phase. The results indicated that corrosion rate of zinc alloy was greatly enhanced under TEL than that in bulk solution. Pure zinc exhibited minimum corrosion resistance as TEL decreased to 198 mu m. Zinc and its alloy exhibited localized corrosion under TEL while it was more uniform in bulk solution. There were two capacitive loops in high frequency (HF) and middle frequency (MF) respectively, with finite length diffusion in low frequency (LF) presented in EIS. For pure zinc under TEL below 300 mu m an additional inductive loop presented in MF-LF. The corrosion products and morphology were respectively examined by X-ray diffraction (XRD), FTIR (Fourier Transform Infra Red) and SEM-EDS. FTIR micro spectroscopy results indicated that the component of the corrosion products was similar at different section of the specimen surface but different in content.
9 citations
TL;DR: In this article, the deformation behavior in magnesium single crystal under c-axis tension was investigated in a temperature range between 250 K and 570 K by molecular dynamics simulations, where twinning and shear bands were found to be the main deformation mechanisms.
Abstract: The deformation behavior in magnesium single crystal under c-axis tension is investigated in a temperature range between 250 K and 570 K by molecular dynamics simulations. At a low temperature, twinning and shear bands are found to be the main deformation mechanisms. In particular, the 10 12 tension twins with the reorientation angle of about 90° are observed in the simulations. The mechanisms of 1012 twinning are illustrated by the simulated motion of atoms. Moreover, grain nucleation and growth are found to be accompanied with the 1012 twinning. At temperatures above 450K, the twin frequency decreases with increasing temperature. The 10 12 extension twin almost disappears at the temperature of 570K. The non-basal slip plays an important role on the tensile deformation in magnesium single crystal at high temperatures.
8 citations
TL;DR: In this article, the authors studied the thermal fatigue behavior of FGH96, a nickel-base powder metallurgy superalloy, under tension-tension loading at the temperature range from 550 to 720 ◦C.
Abstract: Thermo-mechanical fatigue (TMF) behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550 to 720 ◦C. The results show that TMF fracture mode is intergranular for the in-phase (IP), but transgranular cleavage-like for the out-of-phase (OP) samples. The total content of Al, Ti and Nb in the γ′ phases for the IP or OP samples and the partitioning ratio of γ′/γ in these elements for the IP samples are relatively higher at the lower strain amplitude, which is consistent with the case of the γ′ size that is larger at the lower strain amplitude, the lattice parameter misfit is negative and the absolute value is lower at the lower strain amplitude that is correlative with the change of the γ′ morphology. The deformation at the lower strain amplitude is mainly dominated by the dislocation lines and dislocation pairs in the matrix channels, at the higher strain amplitude dominated by the large numbers of superlattice stacking faults within the γ′ phases.
TL;DR: In this article, an ultra-ne grained Fe-40Al intermetallic compound is fabricated by a self-propagating high temperature synthesis (SHS) casting, which exhibits high hardness (3.4 GPa) and high bending strength (830 MPa).
Abstract: 1) State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academyof Sciences, Lanzhou 730000, China2) Graduate University of Chinese Academy of Sciences, Beijing 100039, ChinaManuscript received 22 May 2009; in revised form 10 July 2009An ultraflne grained Fe-40Al intermetallic compound is fabricated by a self-propagating high temperature synthesis (SHS) casting. The XRD result shows thatthe Fe-40Al intermetallic compound consists of the B2 FeAl phase. The Fe-40Al in-termetallic compound presents ultraflne grain size in the range of 100{600 nm, leadingfrom the high nucleation rate and the low growth rate. The Fe-40Al intermetallic com-pound exhibits high hardness (3.4 GPa) and high bending strength (830 MPa) andhigh compressive strength (2700 MPa), which originate from the ultraflne-structurein the material. The efiect of the load on dry-sliding wear rate of the material againstAISI52100 steel was investigated. The wear rate increases with the increase of normalload. The dominated wear mechanism is microfracture.KEY WORDS Iron aluminides; Self-propagating high temperature synthesis(SHS) casting; Ultraflne grain; Preparation; Wear
TL;DR: In this article, the effect of chloride ions on 316L stainless steel in cyclic cooling water was investigated and the results showed that chloride ions had a significant effect on stainless steel.
Abstract: Effect of chloride ions on 316L stainless steel in cyclic cooling water Zuojia LIU , Xuequn CHENG , Shengjie LU 2) and Xiaogang LI 1)∗ 1) Key Laboratory of Corrosion and Protection (Ministry of Education of China), University of Science and Technology Beijing, Beijing 100083, China 2) Equipment and Power Department, Shijiazhuang Refine & Chemical Company Limited, SINOPEC, Shijiazhuang 050032, China Manuscript received 22 April 2010; in revised form 20 August 2010
TL;DR: In this paper, the chemical composition and semi-conductive properties of passive fllm on nickel-based alloy (G3 alloy) in bicarbonate/carbonate bufier solution were investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopic (XPS), electrochemical impedance spectra (EIS), and Mott-Schottky plot.
Abstract: The chemical composition and semi-conductive properties of passive fllm on nickelbased alloy (G3 alloy) in bicarbonate/carbonate bufier solution were investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectra (EIS) and Mott-Schottky plot. AES and XPS results showed that the passive fllm appeared double-layer structure, in which the inner fllm was composed of nickel oxide, the mixed nickel-chromium-molybdenum-manganese oxides were the major component of the outer fllm. The electrochemical results revealed that the factors including frequency, potential, time, temperature and pH value can afiect the semi-conductive property, the doping densities decreased with increasing potential and pH value, prolonging time and decreasing temperature. According to the above results, it can be concluded that the fllm protection on the substrate was enhanced with increasing potential and pH value, prolonging time and decreasing temperature.
TL;DR: In this article, the leachability and fractionation of selected heavy metals (Cr, Cd, Pb and Zn) in the stainless steelmaking plant dusts were studied by the modified HJ/T299-2007 method, the modified TCLP test and a seven-step sequential extraction procedure.
Abstract: The leachability and fractionation of the selected heavy metals (Cr, Cd, Pb and Zn) in the stainless steelmaking plant dusts were studied by the modified HJ/T299-2007 method, the modified TCLP test and a seven-step sequential extraction procedure. The results show that the stainless steelmaking plant dusts are considered as hazardous materials since at least one of the leachable heavy metals exceeds the corresponding limit levels of State Environmental Protection Administration of China. Pb is the most extractable heavy metals by the sequential extraction procedure, while Cr, Cd and Zn mainly presents in the residual fraction bound to spinel phase and silicates. The mobile heavy metals in the dusts, which present as the species of water soluble, exchangeable species and the species bounded to carbonates and hydroxides, can be estimated as 0.08–1.2% of Cr, 7.6%–31.8% of Cd, 34.1% of Pb, 0.052–0.4% of Zn, respectively.
TL;DR: In this article, a series of hexagonal close-packed (HCP) Co-W thin films were deposited by sputtering on surface oxidized silicon substrates at 300 ◦C and a linear dependency of saturation magnetization (Ms) on W content was found up to about 9 at. pct W, and then it underwent an increased Ms vs. W content curve as compared to the initial linear dependency.
Abstract: A series of hexagonal close-packed (HCP) Co-W thin films were deposited by sputtering on surface oxidized silicon substrates at 300 ◦C. A linear dependency of saturation magnetization (Ms) on W content was found up to about 9 at. pct W, and then it underwent an increased Ms vs. W content curve as compared to the initial linear dependency. The thermal magnetization technique was used to confirm that the increased Ms behaviour is correlated to the phase separation of the Co-W thin films. The phase separation behaviour was also found to be dependent on W content and the reason was discussed in detail. Finally an interesting composition range was suggested to be about 13 at. pct–17 at. pct W for the Co-W thin films, in which they exhibit much higher magnetic anisotropy energy than Co-Cr thin films and improved phase separation.
TL;DR: In this paper, the performance of Ni-Ni alloy thin-film electrode materials was characterized with X-ray diffraction (XRD), atom force microscopy (AFM), and scanning electron microscopy.
Abstract: Nano-level Sn-Ni alloy thin-film electrode materials prepared by magnetic sputtering technology are characterized with X-ray diffraction (XRD), atom force microscopy (AFM) and scanning electron microscopy (SEM). The charge/discharge and cyclic voltammograms (CV) of the films electrodes are tested by the battery testing system of high precision. The results indicate that the materials prepared by direct current (DC) and radio frequency (RF) methods differ greatly in their performance. Ni3Sn2 alloy phase constitutes the main components prepared by DC method, the particles on the surface are tiny and show steady cycling performance, the deficiency is that they have low initial efficiency and small discharge capacity of 72% and 108 mA·h/g, respectively. Contrary to the former, Ni3Sn4 alloy phase constitutes the main components prepared by RF method, the particles on the surface appear comparatively larger, their discharge capacity did not decline in the first 15 times, keeping above 500 mA·h/g, but began to decline after 15 times.
TL;DR: In this article, the secondary hardening behavior of water quenched, oil-quenched and air cooled steel are compared by electrolytic extraction, X-ray diffraction, optical microscopy and scanning electron microscopy.
Abstract: 15CrMnMoV rolled tube is applied to many critical parts of helicopter. The secondary hardening behavior of the steel which varied with the treating process is essential for further usage. In this paper, the secondary hardening behavior of water quenched, oil quenched and air cooled steel are compared. The precipitations of alloy carbides are analyzed by electrolytic extraction, X-ray diffraction, optical microscopy as well as scanning electron microscopy. Results show that the secondary hardening effect in the air cooled steel is higher than in the water quenched and oil quenched steel, but the toughness decreases more seriously, due to more precipitation of Mo(2)C and VC.
TL;DR: In this paper, the structure and magnetic properties of Fe-based powders prepared by mechanical alloying were investigated and the structure of Fe powders and their magnetic properties were analyzed.
Abstract: Structure and magnetic properties of Fe-based powders prepared by mechanical alloying Tingdong ZHOU 1,2)∗, Zhengyun WANG , Jiangkang TANG 1) and Haipeng LU 2) 1) Key Laboratory of Special Material and Preparing Technology, Xihua University, Chengdu 610039, China 2) State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China Manuscript received 12 March 2010; in revised form 22 July 2010
TL;DR: In this article, the average IR emissivity of the platinum thin-films was applied to serve as low-emissivity layers to reflect thermal radiation, and the platinum-coated samples were heated in air at 600 ◦C for 200 h to explore the effect of high-temperature environment on the emissivities of coated platinum film.
Abstract: Platinum films were sputter-deposited on two groups of nickel alloy substrates, in which the first group was the samples with rough surface, and the other group with polished surface. The platinum thin-films were applied to serve as the low-emissivity layers to reflect thermal radiation. Then, the platinum-coated samples were heated in air at 600 ◦C for 200 h to explore the effect of high-temperature environment on the emissivity of coated platinum film. After annealing, the average IR emissivity (at the wavelength of 3–14 μm) of the platinum film was only about 0.1 for polished sample and 0.45 for rough sample. The diffusion between platinum and the nickelalloy elements at 600 ◦C had been also discussed.
TL;DR: In this paper, four kinds composites with different compositions were produced, and the mechanical properties and electrical wear performance were investigated; the results showed that the composite added with carbon nanotubes had a higher hardness and strength, a lower contact voltage drop and an excellent anti-wear property in electrical sliding wear.
Abstract: Silver matrix composite brushes were fabricated by means of powder metallurgy, which included pressing at 300 MPa and then sintering for 1 h in pure H2 protective atmosphere at 700 ◦C and repressing at 500 MPa. Four kinds composites with different compositions were produced, and the mechanical properties and electrical wear performance were investigated. The results showed that the composite added with carbon nanotubes had a higher hardness and strength, a lower contact voltage drop and an excellent anti-wear property in electrical sliding wear, because of the reinforcement ability of carbon nanotubes. Adding graphite to the composite also decreased the wear loss and contact voltage drop, because graphite had an electrical current conducting ability which not only made the current pass the lubricating films easily but also eliminated and reduced the arc and spark effectively.
TL;DR: The microstructures and mechanical properties of three X80 pipeline steel plates were investigated in this paper, where the plates were hot rolled by two stages, and cooled by three different cooling schedules to obtain different micro-structures.
Abstract: The microstructures and mechanical properties of three X80 pipeline steel plates were investigated in this study. The plates were hot rolled by two stages, and cooled by three different cooling schedules to obtain different microstructures and mechanical properties. Transmission electron microscope (TEM) was used to observe the microstructure. The results indicated that the amount of polygonal ferrite (PF) and quasi-polygonal ferrite (QPF) decreased with decreasing of the finish cooling temperature (FCT), while the amount and size of M-A islands were larger. Relaxation promoted the Charpy V-notch (CVN) impact toughness at −20 ◦C, but not the drop weight tear testing (DWTT) property at −15 ◦C, and decreased the strength of the steel.
TL;DR: In this article, the authors presented a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode (Mo electrode) in a molten KCl-LiCl-AlCl3-MgCl2-KF system.
Abstract: This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode (Mo electrode) in a molten KCl-LiCl-AlCl3-MgCl2-KF system. It aims at preparation Mg-Li-Al metal alloy directly under an optimal electrolytic parameters. Main factors which affect current efficiency are investigated. We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments, and gained a good electrolytic process. The result of calculation shows that co-electrodeposition Mg, Li and Al occurs at the cathode current density higher than 9 A/cm and electrolytic voltage between 6 to 9 V. And at the optimal parameters, 12–13 A/cm, 620–640 ◦C, the highest current efficiency reaches as high as 86%. Lithium combined with magnesium forms Li0.92Mg4.08 and Li3Mg7, and aluminum mainly exists in a form of Mg0.58Al0.42, distributing in the alpha phases and beta phases.
TL;DR: The effect of strong magnetic fields on faster carbon diffusion and less molybdenum segregation caused by a strong magnetic field was investigated in this article, where a Mo-containing iron alloy was investigated under 12 T magnetic field.
Abstract: The pearlite transformation in a Mo-containing iron alloy was investigated under 12 T magnetic field. The pearlite transformation was accelerated owing to the application of a strong magnetic field. Pearlite was of degenerated morphology without the presence of a strong magnetic field; but the degeneracy of pearlite is reduced when a strong magnetic field was applied, which may be attributed to the effect of strong magnetic field on faster carbon diffusion and less molybdenum segregation caused by a strong magnetic field.