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951.
The Zr62.55Cu17.55Ni9.9Al10 bulk metallic glass (BMG) was prepared by using copper-mold suction-casting. X-ray diffraction and differential scanning calorimetry were utilized to determine its structure and thermal stability. Uniaxial compression and Rockwell indentation tests were adopted to study the plastic deformation behavior at room temperature. The results show that the glass transition temperature and the onset temperature of exothermic reaction of the BMG are 651.5 and 748 K, respectively. During the compression test, the BMGs undergo an engineering strain of about 2.5%, i.e., true strain of 2.8%, and then fracture. The BMGs deform via the formation and propagation of shear bands. Under indentation loading, the BMGs deform through the formation of radiation-like and circular shear bands. The circular shear bands form earlier than the radiation-like ones. The formation mechanism of shear bands in the BMGs was analyzed and discussed. 相似文献
952.
Guang-hui Li Bao Wang Qing Liu Xin-zhong Tian Rong Zhu Li-ning Hu Guo-guang Cheng 《矿物冶金与材料学报》2010,17(6):715-722
The process model for BOF process can be applied to predict the liquid steel composition and bath temperature during the whole steelmaking process. On the basis of the traditional three-stage decarburization theory, the concept of mixing degree was put forward, which was used to indicate the effect of oxygen jet on decarburization. Furthermore, a more practical process model for BOF steelmaking was developed by analyzing the effect of silicon, manganese, oxygen injection rate, oxygen lance height, and bath temperature on decarburization. Process verification and end-point verification for the process model have been carried out, and the verification results show that the prediction accuracy of carbon content reaches 82.6% (the range of carbon content at the end-point is less than 0.1wt%) and 85.7% (the range of carbon content at end-point is 0.1wt%–0.7wt%) when the absolute error is less than 0.02wt% and 0.05wt%, respectively. 相似文献
953.
Effect of Dy substitution on the microstructure and magnetic properties of nanograin Nd-Fe-B single-phase alloys 下载免费PDF全文
Nanocrystalline single-phase alloys with the nominal compositions (at%) of Nd12.3-xDyxFe79.7Zr0.8Nb0.8Cu0.4B6.0 (x=0, 0.5, 1.5, and 2.5) were prepared by melt-spinning and subsequent annealing. X-ray diffraction analysis shows that the as-spun ribbons were mainly composed of the amorphous phase. A slight content of Dy stabilizes the amorphous phase during annealing treatment. The grain size becomes smaller and the coercivity of the annealed ribbon is gradually improved with the increase of Dy content. Excessive Dy is harmful to the remanence. It is found that no intergranular phase exists between the grains by high-resolution transmission electron microscopy, and the grain boundaries are crystallographically coherent in the optimally annealed sample. The optimum magnetic properties of remanence (Jr=1.09 T), coercivity (Hci=1048 kA/m), and maximum magnetic energy product ((BH)m=169.5 kJ/m3) are obtained from the x=0.5 ribbon in a post heat-treated state (700℃, 10 min). 相似文献
954.
Simulation of solute transportation within porous particles during the bioleaching process 下载免费PDF全文
A mathematical model, accounting for the sulfuric acid and ferric ions diffusion and the copper sulfide mineral leaching process, was developed for an ore particle by considering its porous structure. It was simulated with the simulation tool COMSOL Multiphysics. The simulation results show that the highest acid and ferric concentrations near the particle surface are apparent, while the concentrations in the central particle increase slightly as the less-porous ore core with low permeability prevents the oxidation from penetrating. The extraction of the mineral near the particle surface is the maximum, mainly because of ample sulfuric acid, ferric ions, bacteria, and oxygen available for the leaching process. Because of low oxidation concentration in the central part of the particle, the reaction rate and copper sulphide conversion are small. The simulation shows good agreement with the experimental results. 相似文献
955.
A new route of impurity rejection to remove ferric iron from a synthetic nickel leach solution was introduced, which simulated the chemical composition of a typical acid leach solution of nickel laterites under atmospheric pressure. The synthetic solution underwent a stepwise neutralization process, with each step adopting different pH value-temperature combinations. In a conventional nickel atmospheric leach (AL) process, the nickel loss could be as high as 10wt%, which was a longstanding issue and prevented this process from commercialization. The new impurity rejection route is the first step towards resolving this issue. The results show that, the best neutralization performance is achieved at the nickel loss of 3.4wt% in the neutralization scheme that employs ethylenediaminetetraacetic acid as a nickel stabilizer (pH: 1.3–3.5; temperature: 95–70℃) 相似文献
956.
Sheng-li Wu Hong-liang Han Hai-xia Li Jian Xu Shi-dong Yang Xiao-qin Liu 《矿物冶金与材料学报》2010,17(1):11-16
The basic sintering characteristics of Yandi ore from Australia, including assimilation ability, liquid phase fluidity, self-strength of bonding phase, forming ability of silico ferrite of calcium and aluminum (SFCA), and so on, were investigated in detail. Besides, the high temperature behavior and function of sintering were obtained. As a result, the techniques for ore-proportioning in sintering were obtained. The results show that Yandi ore possessing higher assimilation ability, better liquid phase fluidity, lower self-strength of bonding phase, and better forming ability of SFCA, should be mixed with iron ores whose properties are opposite to those of Yandi ore. In the optimization of sintering ore-proportioning, Yandi ore, whose price is relatively low, can be mixed as high as 40wt%. 相似文献
957.
In order to investigate the failure process of brittle rock under triaxial compression through both experimental and numerical approaches, the particle simulation method was used in numerical simulations and the simulated results were compared with those of the experiment. The numerical simulation results, such as fracture propagation, microcrack distribution, stress-strain response, and damage patterns, were discussed in detail. The simulated results under various confining pressures (0–60 MPa) are in good agreement with the experimental results. The simulated results reveal that rock failure is caused by axial splitting under uniaxial compression. As the confining pressure increases, rock failure occurs in a few localized shear planes and the rock mechanical behavior is changed from brittle to ductile. Consequently, the peak failure strength, microcrack numbers, and the shear plane angle increase, but the ratio of tensile to shear microcracks decreases. The damage formation during the compression simulations indicates that the particle simulation method can produce similar behaviors as those observed through laboratory compression tests. 相似文献
958.
Thermodynamic analysis on the formation mechanism of MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spinel type inclusions in casing steel 下载免费PDF全文
MgO·Al2O3 spinel type inclusions in casing steel were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer
(EDS). The results show that there are three forms. One is pure MgO·Al2O3 spinel, another is the composite oxide of the Mg-Al-Ca-Si-O system, and the third is the complex with oxide as a core covered
by sulfide. The formation mechanisms were studied. The influences of slag basicity and vacuum degree on the magnesium content
during the vacuum treatment of molten steel and furnace lining in molten steel were calculated with the coexistence theory
of slag structure. The results show that the magnesium content increases with the increase in slag basicity and aluminum content
in molten steel, and decreases with the increase in CO partial pressure. 相似文献
959.
Metal matrix composites (MMCs) with high specific stiffness, high strength, improved wear resistance, and thermal properties are being increasingly used in advanced structural, aerospace, automotive, electronics, and wear applications. Aluminum alloy-silicon carbide composites were developed using a new combination of the vortex method and the pressure die-casting technique in the present work. Machining studies were conducted on the aluminum alloy-silicon carbide (SiC) composite work pieces using high speed steel (HSS) end-mill tools in a milling machine at different speeds and feeds. The quantitative studies on the machined work piece show that the surface finish is better for higher speeds and lower feeds. The surface roughness of the plain aluminum alloy is better than that of the aluminum alloy-silicon carbide composites. The studies on tool wear show that flank wear increases with speed and feed. The end-mill tool wear is higher on machining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy. 相似文献
960.
A preliminary study of chronology for a newly-discovered ancient city and five archaeological sites in Lop Nor,China 总被引:1,自引:0,他引:1
YIDILISI Abuduresule 《科学通报(英文版)》2010,55(1):63-71
In the past century, it has long been debated in the archeological, historical, geographical, and many other related communities where the capital of the Luolan and Shanshan states was in the Lop Nor region. This paper presents three AMS radiocarbon ages from a newly-discovered ancient city at about 6.3 km to the northwest of the Xiaohe Graveyard, and fifteen new radiocarbon ages from the Loulan (LA), LE, Qieerqiduke, Milan, and Tuyin sites in Lop Nor. The new investigation shows that the age of newly-disco... 相似文献