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Abstract  

A systematic study of Al-Zn-Sn ternary alloys by using a Tian-Calvet calorimeter with slow heating and cooling rate was carried out and supplemented by scanning electron microscopic observations. The results have shown that crystallization coupled with dissolution of tin into the αss′ ternary solid solution on heating is an endothermic process, while melting coupled with tin expulsion on cooling is an exothermic one. It seems that the thermal effects of phase transition are outweighed by much stronger ones due to a large composition change of the αss′ ternary phase.

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Abstract  

The Al–Ga–Zn ternary phase diagram presents two isobaric invariant reactions: a eutectic at 231C and a metatectic at 1231C [1–3]. Calorimetric measurements on the two isobaric invariant reactions have been carried out. First the Tammann method has enabled us to determine the composition of their limits on five isopletic cross sections. Then, the compositions of the invariant phases have been determined.

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Abstract  

The first part of this paper presented five experimental isopletic cuts in the Al-Zn-Ga ternary phase diagram. On these cuts, two isobaric ternary invariant reactions were determined and a significant retrograde miscibility of Ga in a α′SS solid solution was observed. In the second part, the two isobaric invariant reactions are studied more precisely. In particular, the composition of the invariant phases are given and the Ga miscibility in the αSS ternary solid solution is studied. Isothermal sections are established. The results confirm the existence of a vanishing point in the liquidus area, conjugated with a ternary critical point at about 290C. A general perspective shape of the equilibria in the diagram is proposed.

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Abstract  

The magnesium-cerium system has been partially revised in the Ce-rich and Mg-rich regions by using results obtained with the Smith thermal analysis (STA) technique. Nine alloys were examined and, after the thermal measurements,were subjected to phase analysis by means of X-ray powder diffraction (XRD), optical(LOM) and scanning electron microscopy (SEM), and electron probe microanalysis (EPMA).The coordinates of the invariant reactions, many of them very close to each other, were established and compared with literature data where a call for a deeper investigation was proposed as the thermal values were open to different interpretations.

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Abstract  

The Al-Zn-Ga ternary phase diagram was earlier established by thermodynamic modellization [1], but no experimental study appears to have been carried out on this system, except for measurements of mixing enthalpies in the liquid [2]. The present experimental study was carried out by thermal analysis and X-ray diffraction at various temperatures, using the isopletic cuts method. Four isopletic cuts were established and two others were partly studied in the Al-rich corner of the diagram. On these cuts, two isobaric ternary invariant reactions were determined: a eutectic reaction at 231C, and a metatectic reaction at 1231C. Evidence was found for the existence of a retrograde miscibility of Ga in a solid solution α′SS which protrudes into the ternary system starting from the Al-Zn binary up to a Ga concentration of about 30%*.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Hichri, C. Favotto, H. Zamali, Y. Feutelais, B. Legendre, A. Sebaoun, and M. Jemal

Abstract  

Phase diagram of the binary system AgNO3—RbNO3 was studied using thermal analysis technique, differential scanning calorimetry and X-ray diffraction. This binary exhibits a congruently melting compound Ag0.5Rb0.5NO3 (m. p.=138°C), an incongruently melting one Ag0.33Rb0.66NO3 with two polymorphic varieties, two eutectics at (36 mol% RbNO3, 128°C) and at (60 mol% RbNO3, near 134°C) respectively and a peritectic at (60.5 mol% RbNO3, 141°C). This system contains also three invariant reactions at 164, 222 and 282°C due to the phase transitions of RbNO3 and another one at 164°C due to the phase transition of AgNO3.

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Abstract  

Two isothermal sections of the isobaric ternary system H2O–Na2SO4–C5H10NH were determined by isoplethic thermal analysis at 293 and 323 K. The compositions of the aqueous and organic invariant liquids, respectively L1 and L2, as well as that of the critical point, were characterized for each isotherm. The temperature of the invariant reaction was obtained by controlled flow thermal analysis and the temperature of the demixing ending, by interpolation of the monovariant lines. All these informations allowed us to establish the isobaric polythermal diagram of the H2O–Na2SO4–C5H10NH system, for the temperature range 293–323 K, as well as a qualitative representation of the monovariant curves. This system is then characterized by a wide miscibility gap, three crystallization domains, and four-three-phase invariant domains. The relevant exploitation of this diagram so permits us to deduce the demixing temperature leading to the optimal transfer of the organic compounds in the light phase and also the composition of the organic phase recovered after this first step of extraction.

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Journal of Thermal Analysis and Calorimetry
Authors: Ljubiša Balanović, Dragan Manasijević, Dragana Živković, Aleksandra Mitovski, Nadežda Talijan, Duško Minić, and Živan Živković

values given in Table 2 , the liquidus projection of the Al–Ge–Zn ternary system is calculated and plotted in Fig. 2 . One invariant reaction involving liquid phase: ternary eutectic and three primary crystallization areas (FCC_A1 (Al-based solid

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.333 (Va) for vacancy The calculated phase diagram is shown in Fig. 2 . The experimental and calculated temperatures of the invariant reactions are compared in Table 3 . They are in very good agreement. The measured

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Journal of Thermal Analysis and Calorimetry
Authors: A. Iddaoudi, N. Selhaoui, M. Ait Amar, K. Mahdouk, A. Aharoune, and L. Bouirden

therefore, in very good agreement with that of [ 7 ]. The calculated invariant reactions of the Lu–Pb system are listed in Table 3 and compared with the experimental results by [ 6 ]. Fig. 2 Calculated Lu–Pb phase

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