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The thermodynamic activities of liquid CuLa alloys were obtained at 1549 K by Knudsen effusion experiments. The experimentally known concentration and temperature dependences of thermodynamic properties of liquid CuLa alloys are explained on the basis of an association model. These results are discussed in comparison with the enthalpy of crystallization and the crystallization temperature as well as the enthalpy of melting and the melting temperature of lanthanum-rich glassy and crystalline alloys respectively. 相似文献
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S. C. Parida N. S. Anand Ram Avtar Jat S. G. Kulkarni 《Journal of Thermal Analysis and Calorimetry》2013,112(1):173-177
Order–disorder phase transitions in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys have been investigated using differential scanning calorimetry and drop calorimetry. The differential scanning calorimetry measurements show that the transition in both these alloys are reversible in nature and the enthalpy increment measurements reveal that these transitions are first order in nature. The transition temperature of first-order phase transition in Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys have been evaluated to be 884(±2) and 799(±2) K, respectively, from drop calorimetric measurements. The latent heat of first-order phase transition in Cu0.6Pd0.4 alloy were evaluated to be 31.2(±0.6) and 28.9(±0.5) J g?1, by enthalpy increment and differential scanning calorimetry measurements, respectively. Similarly, the latent heat of first-order phase transition in Cu0.85Pd0.15 alloy were evaluated to be 23.1(±0.6) and 21.3(±0.5) J g?1, by enthalpy increment and differential scanning calorimetry measurements, respectively. The solidus temperatures of Cu0.6Pd0.4 and Cu0.85Pd0.15 alloys were found to be 1,457(±2) and 1,360 K, respectively. 相似文献
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《Annales de Chimie Science des Materiaux》2002,27(3):99-109
The processing of metallic alloys through the procedure of equal-channel angular pressing (ECAP) provides an opportunity for achieving superplastic ductilities at very high strain rates. This paper reports experimental data from an investigation of a series of AlMgScZr alloys processed by ECAP. The results show the occurrence of high tensile ductilities at testing strain rates above 10−2 s−1. 相似文献
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Nivedita Dutta Chowdhury K. S. Ghosh 《Journal of Thermal Analysis and Calorimetry》2017,129(2):623-628
The methods of directed crystallization and thermal analysis were used to construct the section Cu0.19Fe0.33S0.48–Cu0.31Fe0.23S0.46 of the liquid–solid diagram of the Cu–Fe–S system. Pyrrhotite solid solution (Fe, Cu)S1±δ (Poss) and nonstoichiometric isocubanite Cu1.1Fe2.0S3.0 (Icb*) form from melt (L) successively. Isocubanite forms at 970 °C by peritectic reaction L + Poss → Icb*. At 930 °C, peritectic reaction L + Icb* → Iss proceeds with formation of intermediate solid solution with average composition Cu1.0Fe1.2S2.0 (Iss). On the basis of the results from this paper and earlier published works, we built a fragment of liquidus surface for the Cu–Fe–S system in the crystallization field of nonstoichiometric isocubanite and stoichiometric isocubanite CuFe2S3 (Icb). 相似文献
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Sajad Amirinejhad Ramin Raiszadeh Hamid Doostmohammadi 《Journal of Thermal Analysis and Calorimetry》2013,113(2):769-777
The oxidation of Al alloys containing 0.3–4.5 wt% Mg in an atmosphere with a very low oxygen partial pressure (<0.5 ppm, to depict the atmosphere within a double oxide film defect) was studied using differential scanning calorimetry and scanning electron microscopy. The results showed that a newly formed Al2O3 layer held in an Al–Mg melt first transformed to MgAl2O4 spinel and then to MgO. This mechanism was the same for all the Al alloys containing 0.3–4.5 wt% Mg, but the kinetics of the transformations were different and depended on the Mg content of the melt. The results also suggest that the two layers of a double oxide film defect that is held in an Al melt containing 0.3–4.5 wt% Mg can heal (i.e. bond to each other) if held in the liquid metal for a long enough period of time. 相似文献
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Çiğdem Özay Elif Beyza Gencer Azim Gökçe 《Journal of Thermal Analysis and Calorimetry》2018,134(1):23-33
A non-commercial Al4Cu0.5Mg alloy has been used for investigating the effects of the elemental Sn additions. Uniaxial die compaction response of the alloys in terms of green density was examined, and the results showed that Sn addition has no effect when compacting conducted under high pressures. In total, 93–95% green density was achieved with an applied pressure of 400 MPa. Thermal events occurring during the sintering of the emerging alloys were studied by using differential scanning calorimetry (DSC). First thermal event on the DSC analysis of the Al4Cu0.5Mg1Sn alloy is the melting of elemental Sn, whereas for Al4Cu0.5Mg alloy, it is the formation of Al–Mg liquid nearly at 450 °C. Also it is clearly seen on the DSC analysis that Sn addition led to an increase in the formation enthalpy of Al–Mg liquid phase. High Sn content and high sintering temperature (620 °C), therefore high liquid-phase content, caused decrease on the mechanical properties due to thick intergranular phases and grain coarsening. Highest transverse rupture strength and hardness values were obtained from Al4Cu0.5Mg0.1Sn alloy sintered at 600 °C and measured as 390 MPa and 73 HB, respectively. 相似文献
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Ljubiša Balanović Dragana Živković Dragan Manasijević Duško Minić Vladan Ćosović Nadežda Talijan 《Journal of Thermal Analysis and Calorimetry》2014,118(2):1287-1292
The results of calorimetric study of binary Al–Zn system done according to the Oelsen thermodynamic method are presented in this paper. Main thermodynamic properties, including activities, activity coefficients, partial/integral molar Gibbs excess, and mixing energies were determined at 1,000 K. Positive deviation from Raoult law was noticed, with minimal values of ΔG M about ?3 kJ mol?1 and maximal values of ΔG E about +2 kJ mol?1. The energetics of mixing in liquid Al–Zn alloys has been analyzed through the study of concentration fluctuation in the long-wavelength limit, and weak affinity between Al and Zn atoms in the system was observed. Differential thermal analysis and light optic microscopy were applied in the frame of characterization of investigated binary alloys and phase diagram examination, and the results obtained were in accordance with available literature data. 相似文献
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《Journal of the Less Common Metals》1987,127(1):183-191
The excess enthalpies of the liquid alloys GaGeTe and GaSnTe were measured in a heat-flow calorimeter at 1203 K. The enthalpy surface in the ternary space in both systems is characterized by a valley stretching from the exothermic minimum in the GaTe system to the minima of the GeTe and SnTe systems. The minima in the ternary systems were found in this valley, i.e. on the sections Ga2Te3-GeTe and Ga2Te3-SnTe. A comparison of the experimental data with those calculated from the excess enthalpies of the constituent binaries with the aid of the Bonnier model, reveals only small deviations. A preliminary investigation was made into the ternary phase diagram of GaSnTe. This system contains the two quasibinary sections Ga2Te3-SnTe, GaTe-SnTe and the ternary compound Ga6SnTe10. The previously reported compounds Ga2SnTe3 and GaSnTe2 do not exist. 相似文献
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《Journal of the Less Common Metals》1987,127(1):147-153
The CeFe binary system was investigated and an FeCe binary phase diagram was proposed. This system consists of
- 1.(i) two peritectic reactions, γ-Fe + L → Ce2Fe17 and Ce2Fe17 + L → CeFe2, occurring isothermally at 1063°C and 925°C respectively;
- 2.(ii) a eutectic reaction, L → CeFe2 + Ce, occurring isothermally at 592°C with eutectic containing 83.3 at.% Ce (92.6 wt.% Ce);
- 3.(iii) a peritectoid reaction, γ-Fe + Ce2Fe17 → α-Fe(Ce), occurring isothermally at 922 °C.
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D. S. Dias Marisa S. Crespi M. Kobelnik C. A. Ribeiro 《Journal of Thermal Analysis and Calorimetry》2009,97(2):581-584
PHB [poly (3-hydroxybutyrate)], post-consumer soft-drink bottles poly (ethylene terephthalate) PET (herein named PET-R) and
PHBPET-R (blends of PHB and PET-R in several compositions) samples were evaluated by differential scanning calorimetry (DSC)
and scanning electronic microscopy (SEM) in order to verify their thermal properties and porosity according to amounts of
PET-R added the blends. The DSC curve showed that the solvents used to solve the polymer mixture cause changes in the thermal
behavior of PET-R films and in PHBPET-R blends. SEM studies of the PHBPET-R blends show that with a gradual mass increase
of PET-R, there are gradual increases in the porosity of the films. 相似文献
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Arpit Kaistha Vivek Modgil V. S. Rangra 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1323-1331
The glassy compositions of Ge 16 Se 52 Te 32?x Sb x system, obtained using rapid melt quenching technique, have been characterized by calorimetric study at different heating rates in this study. A systematic investigation of the crystallization kinetics is carried out for these compositions. Composition corresponding to atomic % 8 of Sb has good thermal stability. The material exhibits the unique thermal properties, which makes it suitable to use for electrical or memory switching devices. Various thermal parameters, activation energies of glass transition and crystallization are calculated using relevant approaches. 相似文献
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《Electrochemistry communications》2008,10(1):32-37
Localized corrosion of aluminum alloys is a major issue worldwide and in spite of decades of work, several questions still remain unresolved. In this study we focus on key issues in the context of localized corrosion of Al–Cu–Mg/Al–Mg–Cu alloys that have not been adequately addressed. By careful electrochemical exposure along with high-resolution electron microscopy, we reveal that microstructural features down to a few nanometers in size can behave as unique electrochemical entities. In addition, not only is this critical to emerging damage accumulation models, but we also reveal that significant dissolution can occur at potentials below the breakdown potential of the bulk alloy. This work has potentially wide consequences in the interpretation of Al alloy corrosion and alloys design for corrosion resistance. 相似文献
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We investigated of the kinematic viscosity of liquid Cu–Sn alloys upon heating and subsequent cooling by the method of the oscillating cylinder. For the liquids alloys Cu75Sn25, Cu50Sn50, Cu48Sn52, Cu32Sn68, and Cu17Sn83, the temperature dependencies of the viscosity upon heating deviate from the Arrhenius relation. The temperature dependencies of viscosity show the Arrhenius-like behaviour upon cooling for all investigated alloys. A discrepancy between the temperature dependencies of viscosity obtained upon heating and cooling arised. We built the concentration dependences of the kinematic viscosity of liquid Cu–Sn alloys upon cooling. The increase of the values of viscosity and activation energy of viscous flow in the concentration range corresponding to the existence of intermetallic compounds Cu3Sn in the solid state was observed. These results were qualitatively interpreted using the concept of microheterogeneities of liquid alloys. 相似文献
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《Journal of solid state chemistry》1986,63(2):129-138
Two new oxyborate compounds were synthesized during a study of the phase relationships between the pinakiolite-ludwigite series of compounds. The structural topologies of these previously unreported materials have been determined experimentally by comparing calculated with observed electron microscope images. Both of these structures are very similar to each other, and also closely related to pinakiolite which consists of flat walls of edge-sharing octahedra connected to zigzag chains of octahedra by triangular BO3 groups. The two new structures contain similar infinite walls which are separated by slabs of octahedra that are wider than the zigzag chains found in pinakiolite. A new series of structurally related oxyborate compounds can be envisaged and are described. 相似文献
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《Annales de Chimie Science des Materiaux》2001,26(1):113-119
A fluorine - oxygen substitution with yo at% F (yo = 2, 3 and 4) was performed in lead zirconate titanate ceramics with the nominal composition Pb0.89(Ba, Sr)0.11(Zr0.52Ti0.48)O3 (PBSZT). This starting material was also doped with x at% Mg (x = 0.4, 0.75 and 1). The dielectric and piezoelectric properties of undoped, (yo at% F) doped, (x at% Mg) doped and (x at% Mg and yo at% F) co-doped PBSZT ceramics were compared. The study of three coefficients - ϵτ, d33 and Qm - revealed that F doping did not induce significant changes in PBSZT characteristics whereas (Mg and F) co-doping led to harder ceramics than MgO only doping. The influence of the different substitutions on the temperature dependence of the dielectric constant and losses have been investigated. A drastic increase of the Curie point was observed after (Mg and F) co-doping associated with a diffuse ferroelectric/paraelectric phase transition. Experimental results indicated that neither Mg nor F has a dominating effect on the characteristics of these co-doped PBSZT specimens 相似文献