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《Journal of Non》2005,351(6-7):604-611
We report on the structural evolution of melt-spun Fe33Zr67 and Fe90Zr10 glasses. These glasses are subjected to isothermal annealing over a wide temperature range, varying from the onset of crystallization up to near the melting point, for 20–300 min. Over 733–1223 K, the phase evolution sequence of the Fe33Zr67 glass follows: fcc FeZr2 → fcc FeZr2 + bct FeZr2 → bct FeZr2. In contrast, annealing of the Fe90Zr10 glass over 903–1173 K leads to a mixture of α-Fe, Fe3Zr and Fe2Zr phases. Some Fe2Zr crystals are not developed perfectly, showing a special twin lamellar structure. The annealing temperature and alloy composition dependence of grain size in the present Fe–Zr system is discussed. 相似文献
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A structural investigation has been made of alloy glasses a low concentration of zirconium: compositions M100?xZrx with M = Fe, Co and Ni, and x = 9 at.% using X-ray diffraction. The characteristic second peak splitting in the radial distribution function is found for all samples presently investigated. The partial radial distribution functions of amorphous FeZr and CoZr alloys were derived from the measured total distribution function data by applying the concentration method with the anomalous scattering technique. The amplitude in the oscillation of the radial distribution function for M-M and M-Zr pairs is more enhanced in comparison with that of glasses with high Zr content, x = 40–45 at.%. The estimated coordination number of nearest neighbor Fe atoms (11.6 ± 0.5) for iron in the Fe84Zr16 glass is larger than that (10.7 ± 0.5) found in the Fe83B17 glass. This is consistent with the measurements of magnetic properties of these glasses with low zirconium concentration. The possible structural features of intertransition metal alloy glasses with low zirconium concentration is also discussed based on the present experimental data. 相似文献
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Tony Spassov 《Crystal Research and Technology》1992,27(2):149-156
Nucleation kinetics, linear growth rate and overall isothermal crystallization kinetics of Pd Si amorphous alloy are studied by means of DSC and optical microscopy. It is found that both the histograms of the crystallite sizes and the DSC isotherms (resp. the time dependences of the degree of transformation α(t)) are best described by the model comprosing the simultaneous occurrence of two reactions of crystallization: heterogeneous as well as homogeneous non-stationary nucleation with subsequent three-dimensional growth in both cases. From the fit of the experimentally measured and the calculated according the model thus proposed distribution curves Ni(Φ) the stationary rates of heterogeneous and homogeneous nucleation, the number of quenched-in nucleation sites and the transient time lags of heterogeneous and homogeneous nucleation have been estimated. Using the values of these parameters kintic curves degree of transformation vs. time have been generated, which are closed to the exerimental x(t) curves obtained by means of DSC at isothermal conditions. 相似文献
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《Journal of Non》2007,353(32-40):3429-3433
The formation of amorphous and quasicrystalline phases in the Ti45Zr38Ni17 system both directly by mechanical alloying and after subsequent annealing was studied. The presence of amorphous, icosahedral quasicrystalline and the Ti2Ni-type with a fcc structure phases together with the initial metallic components was found in as-milled samples by X-ray diffraction. An increase of the milling time results in an increase of the amorphous phase content. Icosahedral quasicrystalline phases of Ti–Ni–Zr system were produced by mechanical alloying and subsequent annealing. Differential scanning calorimetry studies up to 520 °C showed an extended exothermal effect starting from 300 °C, which corresponds to the crystallization of the as-milled samples. The shape and size of the particles of the alloys were investigated by scanning electron microscopy and argon adsorption. The Specific area surface of the as-milled sample was rather small, in agreement with scanning electron microscopy data. The kinetics of the hydrogenation of the amorphous alloy Ti45Zr38Ni17 at different temperatures was studied. 相似文献
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本文以超白玻璃为衬底,利用热丝化学气相沉积和磁控溅射法制备了Glass/nc-Si/Al的叠层结构,然后置于管式退火炉中在H2气氛下进行5h诱导晶化,用XRD、光学显微镜、扫描电镜和拉曼光谱对样品进行了表征.结果表明所有样品都是有(111)择优取向的多晶硅薄膜,在425℃诱导时,多晶硅晶粒尺寸最大达400 μm,但薄膜不连续;随着诱导温度升高到450℃,样品表面已形成了连续的多晶硅薄膜,但晶粒尺寸有所减小;475℃下诱导获得的最大晶粒尺寸约为200μm,此时多晶硅薄膜的结晶质量更好.还从动力学的角度分析了铝诱导纳米硅的晶化机理. 相似文献
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《Journal of Non》2007,353(16-17):1670-1675
A series of alloys designed along a Ti9(Ni,Co)4–Zr e/a-variant line in the Ti–Zr–(Ni, Co) pseudo-ternary alloy system, are investigated by XRD and TEM. Experimental results show that bulk icosahedral quasicrystals (IQC) prepared by copper mold suction casting, can be obtained in a large region from Ti55Zr20(Ni,Co)25 to Ti34.6Zr50(Ni,Co)15.4 with Ni/Co ratio equal to 3/1, and in a sharply diminished region from Ti48Zr30(Ni,Co)22 to Ti42Zr40(Ni,Co)18 with decreased Ni/Co ratio equal to 2/2 or 1/3. Ti48Zr30Ni16.5Co5.5 is the optimal quasicrystal-forming composition, where a nearly pure bulk IQC phase is achieved. The stepwise substitutions of Co for Ni in this pseudo-ternary system contribute to the formation of Ti2Ni, fcc-Zr2Ni, C14-type Laves and β-(Ti, Zr) solid solution phases. However, these substitutions greatly reduce the forming ability of the IQC phase. It is suggested that Co is essentially unfavorable to Ti/Zr-based quasicrystal formation. 相似文献
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《Journal of Non》2007,353(32-40):3338-3341
A series of glass forming alloys (Ti33Zr33Hf33)100−x−y(Ni50Cu50)xAly (x = 20–70 at.% and y = 0–30 at.%) have been developed by equiatomic substitution of similar elements. Of these alloys (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 was chosen in this study to investigate the structural relaxation and glass transition behavior. The as-quenched (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy was fully amorphous and had a wide supercooled liquid region ΔT = Tx(503 °C) − Tg(433 °C) = 70 °C, where Tg and Tx are the glass transition and crystallization temperatures, respectively. Low temperature pre-heat treatments of the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy for 10 min at 310 °C, 370 °C and 390 °C caused structural relaxation accompanied by the formation of very fine scale lattice ordering. After these heat treatments, the glass transition became hard to observe in the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy. Increasing the pre-heat treatment temperatures and holding times caused the glass transition to become more clearly detectable with increasing endothermic heat release. 相似文献
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《Journal of Non》2007,353(32-40):3108-3112
The experimental results for the magnetic susceptibility and superconducting transition temperature of amorphous Zr–(Co, Ni, Cu) alloys extending over a wide composition range are analyzed in some detail. By combining the results of this analysis with the literature results for the electronic density of states at EF for the same alloy systems we obtained a set of parameters associated with the electronic structure of the amorphous Zr. The comparison of these parameters with the results of the band structure calculations for different crystalline phases of Zr and with the results of the atomic structure and crystallization studies of the same alloy systems indicates an fcc-like local atomic structure for amorphous Zr. 相似文献
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《Journal of Non》2007,353(8-10):962-964
The optical and magneto-optical (MO) properties of {CoFeZr(x)–aSi(y)}n and {CoFeZr(x)–SiO2(y)}n composite films with multilayer structure were investigated. It was shown that the form and magnitude of the MO spectra strongly depend of the magnetic and non-magnetic layer thickness and component of non-magnetic material. The MO spectra were analyzed in the framework of the effective-medium approximations and macroscopic Fresnel magneto-optics to ultrathin layers. 相似文献
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V. I. Pet’kov A. I. Orlova G. I. Dorokhova Ya. V. Fedotova 《Crystallography Reports》2000,45(1):30-34
Double zirconium and 3d-transition metal phosphates of the compositions M 0.5Zr2(PO4)3[M = Mn (I), Co (II), Ni (III), Cu (IV), Zn (V)] have been synthesized and the types of their structures have been refined. Compounds I, II, III, IV, and V are all monoclinic (sp. gr. P21/n, Z = 4) and have the unit cell parameters a = 12.390(3), 12.389(3), 12.385(3), 12.389(3), 12.389(2) Å; b = 8.931(4), 8.928(3), 8.924(4), 8.925(4), 8.929(3) Å; c = 8.843(3), 8.840(2), 8.840(3), 8.841(3), 8.842(2) Å, β = 90.55(1), 90.54(1), 90.53(1), 90.53(1), 90.54(1)°; V = 978.5, 977.7, 977.0, 977.4, 978.1 Å3, respectively. All the structures have the {[Zr2(PO4)3]?}3∞-type frameworks. The crystallographic data for 3d-transition and alkali earth metal phosphates described by the general formula M 0.5Zr2(PO4)3 are compared. 相似文献
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K. G. Efthimiadis G. Stergioudis S. C. Chadjivasiliou I. A. Tsoukalas 《Crystal Research and Technology》2002,37(8):827-833
Experimental results are presented regarding the variation of the atomic magnetic moment, the Curie temperature and the crystallization temperature of Fe78‐cMcSi9B13 (M = V, Nb, Mo) and Fe75‐cMcSi9B16 (M = Ni, Cu, Pd, Ag) amorphous alloys. Efforts were made to explain qualitatively the phenomena, based on the behavior of the amorphous alloys when various admixtures substitute Fe atoms. 相似文献
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The structures of microcrystalline AlSiMg alloys during heat treatment were studied using optical microscope Reichert MeF2 equipped with a monochrome TV camera VS-700. The average size of the silicon particles was determined. The significant influence of magnesium on the microstructure at high temperatures was demonstrated. Magnesium accelerates the structure coarsening process and a decrease of the effective activation energy of the silicon particles growth was found. 相似文献
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本文综述了近年来国内外研究者在纳米金刚石薄膜的掺杂、导电性能、场发射性能和电化学性能等方面的工作,涉及化学气相沉积法制备n型纳米金刚石薄膜,离子注入掺杂纳米金刚石晶粒提高薄膜的n型导电性能,金属离子注入制备场发射性能良好的纳米金刚石薄膜,低剂量离子注入和晶粒表面氧终止态获得高迁移率n型电导,纳米金刚石/石墨烯复合结构的调控对其电学及电化学性能的影响,以及硼掺杂金刚石薄膜电极的微结构和电化学性能研究等。综合分析发现,晶粒掺杂和表界面协同调控可以提升薄膜的电学性能、场发射性能及电化学性能,为纳米金刚石薄膜在纳米电子器件、电化学电极等领域的应用提供了理论基础。 相似文献
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铝诱导晶化法(AIC)是一种低温制备大晶粒多晶硅薄膜的重要方法.本文分别基于Al/Al2O3/a-Si叠层和a-Si/SiOx/Al叠层制备了AIC多晶硅薄膜,前者表面粗糙,后者表面光滑.以后者为籽晶层,在其上用HWCVD法300℃低温下外延生长了表面形貌与籽晶层相似的多晶硅薄膜.铝诱导晶化过程中,在原始非晶硅层中会形成多晶硅、非晶硅和铝的混合层,去除铝后残留的硅将使表面粗糙,而在原始铝层中则形成连续的多晶硅薄膜.Al/Al2O3/a-Si 叠层和a-Si/SiOx/Al叠层的上层分别是非晶硅层和铝层,发生层交换后,前者上层是硅铝混合层,因此表面粗糙,后者上层是连续的多晶硅薄膜,因此表面光滑.在AIC多晶硅薄膜表面外延生长多晶硅薄膜等效于铝诱导多晶硅的晶核在垂直于薄膜方向上的继续生长,因此外延生长的薄膜与AIC多晶硅薄膜呈现相似的枝晶状形貌. 相似文献