共查询到20条相似文献,搜索用时 15 毫秒
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M. Jurczyk 《Journal of Materials Science》2004,39(16-17):5271-5274
Nanocrystalline TiFe- and Mg2Ni-type alloys were prepared by mechanical alloying followed by annealing. The structure and electrochemical properties of these materials were studied. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. It was found that the respective replacement of Fe in TiFe by Ni and Mn improved not only the discharge capacity but also the cycle life of these electrodes. On the other hand, a partial substitution of Mg by Mn in Mg2?x M x Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of the nanocrystalline alloys and the electrodes characteristics were investigated. In Mg2Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. 相似文献
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New materials produced by mechanical alloying 总被引:2,自引:1,他引:1
The application of mechanical alloying (MA) to alloys based on Fe, Cu, Al, Ti, Co, Ni, Mg, and Nb is reviewed. Enhancement in physical and mechanical behavior, beyond ingot metallurgy and rapid solidification levels, can be achieved by MA, and should lead to commercialization of a number of MA alloys.Conducted under the joint Moscow-Moscow program on Synthesis of Advanced Materials (SAM). 相似文献
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N. Al-Aqeeli G. Mendoza-Suarez C. Suryanarayana R.A.L. Drew 《Materials Science and Engineering: A》2008,480(1-2):392-396
Al-based binary (Al–Mg) and ternary (Al–Mg–Zr) elemental powder mixtures were mechanically alloyed to develop new Al–Mg–Zr nanocomposite materials. The phase evolution was studied in the as-milled and heat-treated powders by XRD and TEM/EDS analyses. For the binary Al–Mg alloy, the predominant phase was an Al(Mg) solid solution (SS) and an amorphous phase was not possible to be synthesized. Upon adding 5 at.% Zr to the Al–10Mg blended powder, some free Mg was present in addition to the formation of an Al(Zr,Mg)SS, which transformed to the Al3Zr intermetallic after annealing. When the Zr content was increased a nanocomposite of a solid solution and an intermetallic was obtained with considerable improvement in terms of structural stability and hardness. The presence of an oxide phase at 35% Zr might be responsible for the increased hardness in this particular alloy. 相似文献
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The alloying behaviour in a number of systems such as Cu-Ni, Cu-Zn, Cu-Al, Ni-Al, Nb-Al has been studied to understand the
mechanism as well as the kinetics of alloying during mechanical alloying (MA). The results show that nanocrystallization is
a prerequisite for alloying in all the systems during MA. The mechanism of alloying appears to be a strong function of the
enthalpy of formation of the phase and the energy of ordering in case of intermetallic compounds. Solid solutions (Cu-Ni),
intermetallic compounds with low ordering energies (such as Ni3Al which forms in a disordered state during MA) and compounds with low enthalpy of formation (Cu-Zn, Al3Nb) form by continuous diffusive mixing. Compounds with high enthalpy of formation and high ordering energies form by a new
mechanism christened as discontinuous additive mixing. When the intermetallic gets disordered, its formation mechanism changes
from discontinuous additive mixing to continuous diffusive one. A rigorous mathematical model, based on iso-concentration
contour migration method, has been developed to predict the kinetics of diffusive intermixing in binary systems during MA.
Based on the results of Cu-Ni, Cu-Zn and Cu-Al systems, an effective temperature (T
eff) has been proposed that can simulate the observed alloying kinetics. TheT
eff for the systems studied is found to lie between 0·42–0·52T
1. 相似文献
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The development of nanostructured materials offers new scientific and technological perspectives due to the specific interesting physical properties of these materials. These properties derive either from their reduced grain size or from the structure and properties of the grain boundaries, which constitute a significant volume fraction. Mechanical alloying, widely used to produce dispersion-strengthened and amorphous alloys, has been employed in recent years to synthesize nanocrystalline metallic, semiconductors, and covalent component-based materials. Based on statistical analysis of transmission and scanning electron microscopic images, the distribution and spatial repartition of the nanostructural material prepared by mechanical alloying and/or attrition are presented for some specific cases. 相似文献
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A mixture of pure Mg and Si powders with an atomic ratio 2:1 has been subjected to mechanical alloying (MA) at room temperature to prepare the Mg2Si thermoelectric material. Mg2Si intermetallic compound with a grain size of 50 nm can be obtained by MA of Mg66.7Si33.3 powders for 60 hours and subsequently annealed at 620 degrees C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 800-900 degrees C under 50 MPa. The shrinkage of consolidated samples during SPS was significant at about 250 degrees and 620 degrees C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 800 degrees C consists of only nanocrystalline Mg2Si compound with a grain size of 100 nm. 相似文献
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为开发新型金属材料,采用机械合金化与放电等离子烧结的方法制备Fe-Fe3Al合金.根据Fe-Al二元相图与研究经验,对成分及工艺进行优化设计.用X射线衍射仪(XRD)对成分进行了定性分析,用扫描电子显微镜(SEM)观察了样品的表面与断口形貌,进行了能谱分析,并测试了致密度、显微硬度(HV)及抗弯强度、抗拉强度等力学性能.结果表明:对粉末进行预球磨,并在球磨前后对粉末进行搅拌混合处理,能更好地促使Fe与Al在高能球磨的过程中反应;经放电等离子烧结能够制备出Fe3Al/Fe两相材料,相对密度为99%以上,硬度为HV561,抗弯强度1426 MPa,抗拉强度640 MPa,力学性能优于文献报道的值. 相似文献
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Elemental aluminium, titanium and iron powders with compositions of Al90Ti10, Al55Ti45, Al65Ti25Fe10, respectively, were mechanically alloyed in a planetary ball mill. The sequence of phase formation was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Various metastable phases were experimentally observed: supersaturated solid solution Al(Ti) for Al90Ti10, amorphous phase and L12-Al3Ti compound for Al55Ti45, amorphous phase and supersaturated solid solution Al(Ti,Fe) for Al65Ti25Fe10, and an fcc crystalline phase was inevitably found in those alloys. The formation of the fcc crystalline phase has been critically assessed. The results suggest that the fcc crystalline phase seems to be metastable and it cannot be solely attributed to the contamination from the milling atmosphere underthe present experimental conditions. 相似文献
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Mg-based Mg-Ti binary alloys have been synthesized by mechanical alloying of Mg and Ti powder blends. It was found that mechanical alloying of Mg and Ti results in a nanocrystalline Mg-Ti alloy and an extended solubility of Ti in Mg, due to the favorable size factor and the isomorphous structure of Mg and Ti. In the case of Mg-20at.%Ti, about 12.5% Ti is dissolved in the Mg lattice when the mechanical alloying process reaches a stable state. The rest (about 7.5 at.%) remains as fine particles in the size of 50–150 nm in diameter. Dissolution of 12.5 at.% Ti in the Mg lattice causes a contraction of the unit cell volume from 0.0464 to 0.0442 nm3 and a decrease of the c/a ratio from 1.624 to 1.612 of the hexagonal structure. The supersaturated solid solution Mg-Ti alloy decomposes upon thermal annealing at temperatures above 200°C. Hydrogenation enhances the decomposition process at lower temperatures. 相似文献
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高合金铁基粉末冶金材料摩擦磨损性能的研究 总被引:1,自引:0,他引:1
为了获得高性能的耐磨材料,采用粉末冶金方法制备了高合金颗粒强化铁基材料.利用光学显微镜、扫描电镜、能谱分析仪和摩擦磨损实验研究了干摩擦状态下材料的摩擦磨损性能.结果表明:材料的磨损机理是由粘着磨损、磨料磨损和接触疲劳磨损共同作用的.本文研究的高合金铁基粉末冶金耐磨材料,在50 s内进入稳定磨损阶段,能在很短的时间里达到最佳使用效果.干摩擦120 min后,材料的比磨损量小,仅为2.096×10-15 kg/(m.N),摩擦系数变化不大,在0.05~0.06保持相对稳定,说明材料的耐磨性能较好.材料组织中M6C碳化物能保证材料很好的耐磨性能,而M2C碳化物则降低材料的耐磨性能. 相似文献
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采用机械合金化方法用Ni粉和Ti粉得到了Ti3Ni2非晶合金。晶态Ti3Ni2合金初始容量比非晶合金要高。晶态合金初始容量可以达到240mAh/g。而非晶合金容量为173mAh/g。随着循环次数的增加,晶态合金放电容量呈线性下降趋势。而对于非晶电极材料来说,随着循环的进行,初始容量下降,但是达到一定循环次数以后,电极的放电容量达到基本稳定。 相似文献
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J. Foct 《Journal of Materials Science》2004,39(16-17):5011-5017
The first stages of the mechanical alloying process, fragmentation and welding, are analysed. In order to clarify the mechanisms of milling-induced diffusion, different interstitial solid solutions are examined. It is shown that diffusion of interstitial is mainly controlled by the stress field. In case of a substitutional solid solution, the mechanism of atomic transport is controlled by shear deformation. The consequence of the corresponding diffusion models are discussed. 相似文献
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Titanium (Ti) and its alloys possess suitable mechanical characteristics for utilization in orthopedic implants. However, their poor integrity with native tissues is a major challenge in their clinical application. Composite structures of Ti and hydroxyapatite (HA) can be used to promote the bone ingrowth and integration of the implant with the surrounding tissue. Here, we report the fabrication of Ti-HA nanocomposite powders using a high energy planetary ball mill. We investigate the effects of fabrication parameters including HA content (10–30% w/w), milling time (20 and 50 h), and HA particle size (50 nm and 15 μm) on the characteristics of the fabricated composites. In particular, we determine the samples hardness, sintering density, surface roughness and topography for different conditions. The results show that the addition of HA to Ti decreases the sintering density and enhances the surface hardness. Also, we observe a direct relationship between HA concentration in the Ti matrix and the surface roughness. 相似文献