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1.
G. E. Abrosimova A. S. Aronin A. F. Gurov I. I. Zver’kova E. Yu. Ignat’eva 《Physics of the Solid State》1998,40(9):1429-1432
Structural evolution of the amorphous alloy Ni70Mo10P20 has been studied by x-ray diffraction, and by following transmission and high-resolution electron microscopy annealing both
above and below the glass-transition temperature. When annealed above this temperature, the amorphous phase undergoes segregation
into regions about 100 nm in size having different chemical composition. Diffraction from such samples produces diffuse rings,
and the scattering vector corresponding to the maximum intensity varies from point to point within the interval of 4.88 to
4.78 nm−1. When occurring between the glass-transition and crystallization temperatures, crystallization produces groups of nanocrystals,
20–30 nm in size, which are in direct contact with one another and form a polymorphic mechanism. The crystallization mechanism
changes when the annealing temperature is brought below the glass-transition point. At these temperatures the amorphous matrix
crystallizes entectically with formation of eutectic colonies.
Fiz. Tverd. Tela (St. Petersburg) 40, 1577–1580 (September 1998) 相似文献
2.
The evolution of the structure of an amorphous Ni70Mo10P20 alloy during annealing in the temperature range from 673 to 873 K is studied using x-ray diffraction and transmission electron
microscopy. It is found that a previously unknown metastable phase forms during crystallization of the amorphous Ni70Mo10P20 alloy. The morphology of the newly formed crystals is studied, the space group and the lattice constant are determined, and
the atom positions for the phase that forms are proposed. It is found that the metastable phase is a phosphide whose composition
is close to (Ni(Mo))3P. We established that, as the temperature or the duration of annealing is increased further, the metastable phase turns into
the equilibrium Ni3P phase. The orientation relations between the metastable and equilibrium phases are determined. 相似文献
3.
4.
In this Letter, molecular dynamics (MD) simulations based on EAM many-body potential have been performed to investigate the differences of dynamical heterogeneity in the course of crystallization and glass transition, respectively. The crystallization of liquid, detected at a cooling rate of , is characterized by the appearances of the second plateau in mean square displacement (MSD) and the nonzero plateau in non-Gaussian parameter (NGP). It implies that the non-diffusive rearrangement of atoms occurring at a certain temperature and relaxation time leads to nucleus forming. The glass phase forms as the cooling rate increases to . There is no second plateau in MSD appearing in the formation of metallic glass, indicating the diffusive motion of atoms. The non-Gaussian characteristic in NGP is more obvious at low temperatures. 相似文献
5.
45% semi-crystalline parylene-C (–H2C–C6H3Cl–CH2–)
n
thin films (5.8 μm) polymers have been investigated by broadband dielectric spectroscopy for temperatures above the glass
transition (T
g
=90°C). Good insulating properties of parylene-C were obtained until operating temperatures as high as 200°C. Thus, low-frequency
conductivities from 10−15 to 10−12 S/cm were obtained for temperatures varying from 90 to 185°C, respectively. This conductivity is at the origin of a significant
increase in the dielectric constant at low frequency and at high temperature. As a consequence, Maxwell–Wagner–Sillars (MWS)
polarization at the amorphous/crystalline interfaces is put in evidence with activation energy of 1.5 eV. Coupled TGA (Thermogravimetric
analysis) and DTA (differential thermal analysis) revealed that the material is stable up to 400°C. This is particularly interesting
to integrate this material for new applications as organic field effect transistors (OFETs). Electric conductivity measured
at temperatures up to 200°C obeys to the well-known Jonscher law. The plateau observed in the low frequency part of this conductivity
is temperature-dependent and follows Arrhenius behavior with activation energy of 0.97 eV (deep traps). 相似文献
6.
The calorimetric measurements have been made in glassy Se70Te30 and Se70Te28M2 (M?=?Ag, Cd, and Zn) alloys using non-isothermal differential scanning calorimetry technique to see the effects of Ag, Cd, and Zn additives on the glass transition kinetics of binary Se70Te30. From the heating rate dependence of glass transition temperature, T g, different kinetic parameters of glass transition have been evaluated. The composition dependence of glass transition temperature T g and the related activation energy (Et ) is also discussed. 相似文献
7.
The phase transitions in Pd40Ni10Cu30P20 bulk metallic glass (BMG) have been studied under high pressure and high temperature (HP & HT) by X-ray diffraction measurements with synchrotron radiation source. We found that the BMG underwent a phase transitions of amorphous-crystalline-amorphous at 10 GPa upon heating. The parallel experiments were carried out at 7 GPa, while we did not observe the amorphous-crystalline-amorphous transitions by increasing temperature. Quenching the melted BMG at 7 GPa, it was found that the phase crystallized from the melt differed from the primary phase crystallized from the starting amorphous solid upon heating, suggesting there existed a distinct mechanism in two cases. 相似文献
8.
Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) are employed to investigate the effects of nickel on the crystallization of the amorphous Zr70Cu20Ni10 alloy. We have found that the crystallization process of the amorphous Zr70Cu20Ni10 alloy is strongly influenced by the addition of nickel. Addition of 10 at% Ni to the Zr70Cu30 amorphous alloy makes the crystallization process proceed from a single-stage mode to a double-stage mode. The activation energy for crystallization of the amorphous Zr70Cu20Ni10 alloy is calculated to be about 388kJ·mol-1 on the basis of the Kissinger equation. The effects of nickel on the crystallization of the amorphous Zr70Cu20Ni10 alloy are discussed in terms of the genetics of metals. 相似文献
9.
We report here the formation of helium gas bubbles in a nickel based metallic glass Ni45Fe5Co20Cr10Mo4Bl6 after 50 keV helium ion irradiations at room temperature studied by transmission electron microscopy. At higher doses bubbles eventually grow and deform the material surface plastically leading to blister formation. Critical dose for blister formation is determined. Helium gas bubble formation is associated with partial crystallisation of the glass which can be observed from selected area diffraction from the region where bubbles are formed. Micro-hardness measurements are also performed on the irradiated samples as a function of dose. Increase in the microhardness has been observed after a dose at which helium bubbles are formed. 相似文献
10.
11.
用熔融共混法制备了不同组分的聚苯乙烯(PS)与聚氧化乙烯(PEO)共混物(PS/PEO).在玻璃转变温度Tg及其以上温区,利用相对能量耗散技术研究了该共混物的动力学行为.结果发现,在能量耗散-温度曲线上出现了两个弛豫型的耗散峰(α峰和α′峰).分析表明,α峰是与PS玻璃转变有关的特征耗散峰; α′峰则对应于一种“液-液转变”.两者的弛豫时间τ都不满足Arrhenius关系.此外,还研究了组分对这两个弛豫型耗散峰的影响,并给予了定性的解释.
关键词:
相对能量耗散
玻璃转变
力学弛豫 相似文献
12.
X. R. Qian M. X. Chen L. Chen H. J. Jin L. J. Chen G. Q. Xu 《Hyperfine Interactions》1992,69(1-4):585-588
The rapidly queoching samples of Sm20Fe70Ti10 were prepared by melt spinning. The coercivities of crystallized ribbons were found to vary with the spinning velocity. The value of coercivity obtained was 3.2kOe, which is higher than that reached in Sm?Fe?Ti alloys with the ThMn17 structure. The results of Mössbauer effect and X ray diffraction analyses indicate that the alloy consists of SmFe2, SmFe3, an undetermined paramagnetic phase and the minor phase of Sm2Fe17. 相似文献
13.
14.
15.
The effect of rapid heating on the stability of amorphous Fe45Ni35Si10B10 is studied in detail by Mössbauer spectroscopy. Structural relaxation as well as formation of crystalline α-Fe and γ(FeNi) is observed, depending on the heating and cooling conditions applied. 相似文献
16.
We present a direct measurement of self-diffusion of a single-component glass-forming liquid at the glass transition temperature. Forward recoil spectrometry is used to measure the concentration profiles of deuterio and protio 1,3-bis-(1-naphthyl)-5-(2-naphthyl)benzene (TNB) following annealing-induced diffusion in a vapor-deposited bilayer. These experiments extend the range of measured diffusion coefficients in TNB by 6 orders of magnitude. The results indicate a decoupling of translational diffusion coefficients from viscosity or rotation. At T(g), D(T) is 400 times larger than expected from the Stokes-Einstein equation. 相似文献
17.
É. V. Kozlov G. V. Pushkareva V. M. Kushnarenko N. A. Koneva 《Russian Physics Journal》1977,20(1):65-70
Using the methods of transmission and diffraction electron microscopy, we analyze the laws governing the growth kinetics of antiphase domains in the alloy Ni4Mo during its isothermal ordering at 840, 800, and 700°C. The size distributions of the antiphase domains as well as the mean size and central moments of the distributions are determined. It is shown that the growth of the antiphase domains obeys the equation Dn-D
0
n
=Ae–Q/kT. The value of the parameter n is 2.5 for 840 and 800°C, and 5 for 700°C. By considering the isochronous cross section of the kinetic curves, we calculate the activation energy for the growth of antiphase domains; it equals 65 kcal/mole.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 84–89, January, 1977. 相似文献
18.
通过二次离子质谱仪(SIMS)研究了Mo在Zr57Nb5Cu15.4Ni12.6Al10非晶合金中的扩散,并计算出其扩散激活能Q和前置系数D0分别为1.95 eV和1.13×10-5 m2s-1.根据Stokes-Einstern关系式研究了玻璃转变温度以下593-673 K之间Zr57Nb5Cu15.4Ni12.6Al10非晶合金的黏滞特性,得到的黏滞系数从593 K的1.07×1010Poise降到673 K的1.42×108 Poise. 相似文献
19.
《Journal of magnetism and magnetic materials》2005,294(2):e155-e158
The evolution of the magnetic properties of Fe70Cr10B20 alloy, initially in amorphous state, is studied during the whole crystallization process, from room temperature to 800 °C. Neutron thermodiffraction has been used in order to follow all the structural changes that take place in the sample, including the appearance of tetragonal phases and polymorphic transformations. The formation of these tetragonal phases, with high magnetic anisotropy, leads to a degradation of the soft magnetic response. The study of the correlation between structure and magnetic response helps to optimize the composition and heat treatments in these materials for their application in sensor devices. 相似文献
20.
《Solid State Communications》1987,62(6):427-429
Brillouin scattering measurements made in glycerol show a linear temperature coefficient of the hypersound velocity in the glassy state, a break at Tg = 193 K and another linear part up to 280 K. The analysis of the data in the melt state suggests the presence of excitations, which have the formation energy δ = 1400·kB K. The results are compared with those obtained recently with a soliton model for the dynamics of disordered materials. 相似文献