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Effects of Tungsten and Boron Contents on crystallization temperature and Microhardness of Tungsten Based Metallic Glasses

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 733-738页

作者： Pelin ztürk Aytekin Hitit Department of Materials Science and Engineering AfyonKocatepe University

Effects of tungsten and boron contents on the thermal properties and microhardness of W-Fe-B metallic glass system were studied. Thin foils, with thicknesses of 20 and 100 ktm, of the alloys were produced by piston and anvil method in an arc furnace. The structures of the foils were investigated by X-ray diffraction. Thermal stabilities of the alloys were examined by using differential scanning calorimetry. 20-μm- thick foils of all the alloys were determined to be fully amorphous, but crystalline phases were detected in the 100-μm-thick foils. It was found that crystallization temperatures of the alloys are between 1060 and 1177 K. Tungsten and boron content increases improve the crystallization temperature and microhardness of the alloys significantly, but deteriorate the glass forming ability of the alloys. It was also observed that for constant Fe content, increasing tungsten content to the level higher than that of boron content does not result in any further improvement in crystallization temperature, but improves glass forming ability significantly. The alloy containing highest total amount of tungsten and boron, W35Fe35B3o, has the highest crystallization temperature, 1177 K, and microhardness, 1634 HV.

关键词： Metallic glass Refractory metal crystallization temperature Hardness

crystallization kinetics of Sn_(40)Se_(60) thin films for phase change memory applications

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Journal of Semiconductors 2015年第6期36卷 17-20页

作者： Joshua M.Kundu Patrick M.Karimi Walter K.Njoroge Department of Physics Kenyatta University

The crystallization kinetics of Sn4oSe6o thin films has been successfully investigated using sheet resis- tance versus temperature measurements. Thermal evaporation was used to deposit the films on ordinary glass sub- strates. The crystallization temperature for Sn4oSe60 thin film was found to be 156.6 -t- 0.3 ~C. In the as-deposited state, the sheet resistance was found to be 195 Mf2/[2, this value declined to 1560 f2/[2] upon annealing. The value of activation energy obtained from the Kissinger plot was 0.62 ＋ 0.07 eV. From the results obtained, SnaoSe60 is a promising alloy for PCM application because of its high electrical contrast, high crystallization temperature, and relatively high activation energy.

关键词： crystallization temperature activation energy electrical contrast phase change memory

EFFECT OF PRE-ANNEALING ON crystallization KINETICS OF AMORPHOUS Ni-P ALLOYS

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Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 88-92页

作者： LUKe WANG Jingtang Laboratory of Rapidly Solidified Non-Equilibrium Alloys,Institute of Metal Research,Academia Sinica,Shenyang,China Acad Sinica Shenyang China

The effect of pre-annealing treatment on the crystallization kinetics parameters of amorphous Ni-P alloys has been investigated.Experimental results showed that the crystallization tem- perature,T_p and T_x,the apparent activation energy,E_c,as well as the Avrami exponent for isothermal crystallization,n,decrease significantly,while ΔT_(px)=T_p-T_x increases with the elongation of pre-annealing time at 570 K.

关键词： amorphous alloy crystallization kinetics crystallization temperature activation energy for crystallization

Control of the agglomeration of crystals in the reactive crystallization of 5-（difluoromethoxy）-2-mercapto-lH- benzimidazole

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Frontiers of Chemical Science and Engineering 2012年第4期6卷 423-431页

作者： Yongli WANG Shuyuan MA Xiaodong LU Chuang XIE School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China

5-（Difluoromethoxy）-2-mercapto- 1H-benzimi- dazole （DMB） was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch crystallizer was monitored by real-time Particle Video Microscope （PVM）. We found that the low feeding rate of acetic acid, high crystallization temperature, low agitation rate or adding seed crystal can facilitate the formation of spherical agglomerates. By using a simple model, the mean crystal agglomerate size of DMB thus predicted is generally in agreement with the experimental data. In addition, the crystallization process of DMB was optimized by a new control strategy of supersaturation to avoid disadvantages brought by agglomeration.

关键词： 5-（difluoromethoxy）-2-mercapto- 1H-benzi-midazole （DMB） reactive crystallization agglomeration,feeding rate crystallization temperature agitation rate

Effect of Y^(3+), Gd^(3+) and La^(3+) dopant ions on structural, optical and electrical properties of o-mullite nanoparticles

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Journal of Rare Earths 2014年第1期32卷 37-42页

作者： M.M.S.Sanad M.M.Rashad E.A.Abdel-Aal M.F.El-Shahat K.Powers Central Metallurgical R & D Institute Particle Engineering Research Center University of Florida Faculty of Science Ain Shams University

Dielectric ceramics of M（x）Al6（1-x）Si2O13 doped mullite were synthesized via co-precipitation technique. The X-ray diffrac-tion profiles revealed that these nanoparticles were crystallized well and the volume of mullite unit cell was increased as a function of the ionic radius of dopant ion. TEM images showed regular orthorhombic crystal morphology for the pure mullite sample. Meanwhile, the doped samples exhibited slightly distorted crystal morphology of larger particle sizes. DSC thermograms evinced that the exo-thermic peak temperature of mullite was shifted to the lower value with M3＋ion insertion. The photoluminescence spectra were stud-ied for mullite samples, and it was found that the intensity of the emission spectra was affected by the M3＋ion type. It was found that, Y3＋doped mullite achieved the minimum dielectric loss value of 0.01 in the radio wave frequency region （1 MHz）. Meanwhile, Gd3＋doped mullite achieved the minimum dielectric loss value of 0.09 in the microwave frequency region （1 GHz）.

关键词： rare earths doped mullite photoluminescence crystallization temperature dielectric ceramics

EFFECT OF PRE-ANNEALING ON crystallization KINETICS OF Cu-Ti GLASS

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Acta Metallurgica Sinica(English Letters) 1991年第7期4卷 26-30页

The crystallization kinetics of the Cu_(40)Ti_(60) glasses,either as-quenched or pre-annealed,has been studied by differential scanning calorimetry.The crystallization temperature,activation energy for crystallization and Avrami exponent were found to be lowered by the pre-an- nealing.Both activation energies of nucleation and growth of the amorphous CuaoTi_(60) are ob- tained on the basis of experimental results and theoretical analysis.

关键词： metallic glass crystallization temperature activation energy pre-annealing Avrami exponent

Hydrogen absorption properties of amorphous(Ni0.6Nb0.4-yTay)100-xZrx membranes

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Progress in Natural Science:Materials International 2017年第1期27卷 126-131页

作者： O.Palumbo F.Trequattrini N.Pal M.Hulyalkar S.Sarker D.Chandra T.Flanagan M.Dolan A.Paolone CNR-ISC U.O.S. La Sapienza Department of Physics Sapienza University of Rome Department of Chemical and Materials Engineering University of Nevada 4. Department of Chemistry University of Vermont 5. CSIRO QCAT Energy 1 Technology CourtPullenvale

Ni based amorphous materials have great potential as hydrogen purification membranes. In the present work the melt spun(Ni;Nb;Ta;);Zr;with y=0, 0.1 and x=20, 30 was studied. The result of X-ray diffraction spectra of the ribbons showed an amorphous nature of the alloys. Heating these ribbons below T crystallization process was characterized by differential thermal analysis and the activation energy of such process was obtained. The hydrogen absorption properties of the samples in their amorphous state were studied by the volumetric method,and the results showed that the addition of Ta did not significantly influence the absorption properties, a clear change of the hydrogen solubility was observed with the variation of the Zr content. The values of the hydrogenation enthalpy changed from;7 k J/mol for x=30 to;k J/mol for x=20. The analysis of the volumetric data provides the indications about the hydrogen occupation sites during hydrogenation, suggesting that at the beginning of the absorption process the deepest energy levels are occupied, while only shallower energy levels are available at higher hydrogen content, with the available interstitial sites forming a continuum of energy levels.

关键词： Amorphous Ni based alloy ribbons High temperature X-ray diffraction DTA Activation energy crystallization temperature Hydrogen solubility

Effect of Al_2O_3 Content on Residual Stress and Proper-ties of CAS Glass-ceramics

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Journal of Wuhan University of Technology(Materials Science) 2008年第6期23卷 889-892页

作者：谢俊 Key Laboratory of Silicate Materials Science and Engineering (Wuhan University of Technology) Ministry of Education Wuhan University of Technology

The structure and properties of the glass-ceramics were tested with X-ray diffraction testing instrument,correlative software,and other modern testing means.Then the effect of Al2O3 content on internal stresses in CaO-Al2O3-SiO2 glass-ceramics was studied deeply.In order to study the relationship of Al2O3 to the residual stress of CaO-Al2O3-SiO2 glass-ceramics,X-ray diffraction ＂sin2ψ＂ was used.The means utilized the x radial incidence produced from cathode radial tube,and took the space between crystals as measurement of strain.When the stresses produced,the space between crystals changed and the diffraction peak moved during Bragg diffraction.The magnitude of movement is related to the stresses.The experimental results show the residual stress is considerably high and Al2O3 can influence the mechanical properties of this material hugely.

关键词： residual stress Cao-A1203-SiO2 glass-ceramic X-ray diffraction crystallization temperature

On the Structure and Free Volume Properties of Poly（3-hydroxybutyrate-co-3-hydroxyvalerate） Membranes via Various crystallization Conditions

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On the Structure and Free Volume Properties of Poly（3-hydro...