Phase equilibria and crystal structure of ternary compounds in Al-rich corner of Al-Er-Y system at 673 and 873 K

Phase equilibria in the Al-rich corner of the Al-Er-Y ternary system from 65 at.% to 100 at.% Al at 673 and873 K were investigated,and the two isothermal sections were established by X-ray diffraction(XRD),scanning electron microscope(SEM) and electron probe micro analysis(EPMA).Three ternary-phase regions are observed and the phase relations are similar at both isothermal sections.There are two ternary compounds,and a complete crystal structures and composition ranges of the two ternary compounds are determined as τ₁(Al_75-76Er_15-22Y_2-10,R-3 m) and τ₂(Al_75-76Er_11-17Y_7-14,P6₃/mmc) via XRD,focused ion beam coupled with transmission electron microscope(FIB-TEM) and EPMA.Meanwhile,the solubilities of the third element in the binary compounds at both temperatures are measured.The solubility of Er inβ-Al₃ Y phase reaches to 6.6 at.% and that of Y in Al₃ Er phase reaches to 1.5 at.% after annealing at 873 K.The temperature effect is not obvious for the phase equilibria at 673 and 873 K,but it increases the solubility of Er in β-Al₃ Y,while it is not obvious for both the solubility of Y in Al₃ Er and that of Er and Y in(Al).The phase equilibria of the Al-Er-Y ternary system determined by the present work have provided new phase diagram data for a future thermodynamic assessment of this system.     

Calculation of phase equilibria in Al-Fe-Mn ternary system involving three new ternary intermetallic compounds

In this study, the Al-Fe-Mn ternary system is reassessed by the CALPHAD method. Three new ternary intermetallic compounds are initially described and a reasonable and self-consistent set of thermodynamic parameters are established to describe this system. The 973 K, 1 073 K, 1 173 K, 1 273 K, 1 373 K, and 1 473 K isothermal sections and the 1 073 K, 1 013 K, 968 K and 913 K isothermal sections at the Al corner as well as the liquidus projection at the Al corner are calculated. It is shown that the calculated results are in good agreement with almost all of the experimental results previously reported.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-017-0199-0     

Solid-state phase equilibria and thermodynamic properties of ternary compounds in the Tl-Sb-S system

The Tl-Sb-S system has been studied in the composition region Tl₂S-Sb₂S₃-S using differential thermal analysis, X-ray diffraction, and emf measurements on thallium concentration cells at temperatures from 300 to 390 K, and the 300-K isothermal section of its phase diagram has been mapped out. The existence of the ternary compounds TlSb₅S₈, TlSb₃S₅, TlSbS₃, TlSbS₂, Tl₃SbS₄, and Tl₃SbS₃ has been confirmed, and the position of the phase fields involving these compounds has been accurately determined. Using emf data, we have evaluated the partial molar functions (D[`(G)]\Delta \bar G , D[`(H)]\Delta \bar H , D[`(S)]\Delta \bar S ) of the thallium in the alloys studied, the standard thermodynamic functions of formation of the ternary compounds, and their standard entropies.     

Phase equilibria of the ternary Ag-Cu-Ni system and the interfacial reactions in the Ag-Cu/Ni couples

The phases formed at the interfaces of nickel and Ag-Cu alloys were determined by studying the reaction diffusion couples together with the isothermal sections of the Ag-Cu-Ni system at the annealing temperatures. Phase equilibria at 860, 795 and 700 °C, were determined by both experimental investigation and model calculation. The reaction diffusion couples were prepared with either the Ag-15 wt% Cu alloy with nickel foil, or Ag-28 wt% Cu alloy with nickel foil, and were annealed at the three above-mentioned temperatures. The interfaces of the reaction layers in the couples were non-planar. By using microscopes and EPMA, the phase sequences formed in the reaction diffusion couples were determined. These diffusion paths were in agreement with the phase equilibria study, and it demonstrated that the tie triangle shifted towards the nickel side as temperature increased. The thickness of the reacted layers was determined by using an image analyser, and a parabolic growth was found for the Ni/Ag-28 wt% Cu couple annealed at 795 °C.     

An experimental and theoretical study of the glass-forming region of the Mg-Cu-Sn system

The amorphization of Mg-Cu-Sn alloys with various compositions has been studied using the melt-spinning technique, with particular emphasis on the magnesium-rich corner of the ternary phase diagram. The results have been interpreted in terms of Miedema's theory, which highlights competition between the amorphous phase and crystalline solid solutions. Competition by ordered intermetallic compounds has also to be considered in order to explain the restricted amorphization region found in these experiments.CONICET career research worker.     

Contribution to ternary system Al-Ti-B Part 1: Study of diborides present in the alulminium corner

Abstract

Diborides present in Al-Ti-B alloys with a weight ratio TilB < 2.2 are investigated in the arc melted and annealed conditions as well as in the controlled heated and cooled specimens by means of light and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. In Al- Ti-B alloys with composition close to the AlB₂-TiB₂ tieline; apparently pure spheroidal and platelike TiB₂ particles are present. In the as cast condition of all other investigated alloys the formation of AlB₂ on primary TiB₂ particles is observed regardless of the applied cooling rate. In the investigated alloys apparently pure TiB₂ and AlB₂ coexist even after 1000 h exposure at 800° C, and the formation of mixed diboride (Al, Ti) B₂ was never observed. The results of this work are discussed together with the results of previous work in this area and it seems very likely that the mixed diboride (Al, Ti)B₂ is not a thermodynamically stable phase in the aluminium rich corner of the Al-Ti-B system, but onlyapparently pure AlB₂ and TiB₂ are present.     

Phase equilibria in the high magnesia corner of the system MgO-ThO2-B2O3 at 1200° C

Phase equilibria in the high magnesia corner of the system MgO-ThO₂-B₂O₃ were investigated at 1200°C using X-ray powder diffraction techniques. The two magnesium borates reported previously at this temperature were confirmed, but no magnesium thorate and no ternary phases were found. Solid solution effects were investigated; for the binary phases by comparison of patterns, for magnesium oxide and thorium oxide by comparison of lattice parameters. No solid solutions were detected.Phase equilibria in the system MgO-ThO₂ were investigated at 1500°C, again no binary compound was found and no solid solution detected. A suggestion is made to reconcile the latter observation with previous work.     

Phase equilibria in the Ti-rich corner of the Ti-Si-Sn-Al system Part I Section 9Si-1Sn (at.%)

Phase equilibria in Ti-rich corner of the Ti-Si-Sn-Al system were studied using differential thermal analysis, X-ray diffraction, microscopy, and electron microprobe analysis. Projections of solidus and liquidus surfaces, an isothermal section at 1300°C and an isopleth at 9Si-1Sn (at.%) were constructed. It was shown that in the concentration interval studied at the solidus and 1300°C temperatures two two-phase Ti₅(Si,Sn,Al)₃ + <-Ti< and Ti₅(Si,Sn,Al)₃ + <-Ti< regions are present. The liquidus surface is characterised by the regions of and Z primary crystallisation, resulting in bivariant L + Ti₅(Si,Sn,Al)₃ eutectic. The character of horizontal and vertical sections is similar to that for the Ti-Si-Al system.     

Phase equilibria in the Nb-Ge-C system

An experimental survey of the Nb-Ge-C ternary phase diagram was used to determine the equilibrium tie-lines between solid phases in this system. In addition to the binary phases, the system contains a newly discovered ternary phase with an approximate composition of Nb₃GeC, and an extensive solution phase extending into the ternary system from the binary β-Nb₅Ge₃ phase.     

Phase equilibria in the Cu-Se system

The available phase-diagram data for the Cu-Se system are critically evaluated, and theT-x andp-T phase diagrams are optimized. The thermodynamic properties and polymorphism of copper selenides are analyzed.     

Phase equilibria in the V-Ni-Sb system

Phase relations in the V-Ni-Sb system have been studied by x-ray diffraction, and the 1070-K section of its phase diagram has been constructed in the region 0–67 at % Sb. The VSb phase (NiAs structure) is shown to have a homogeneity range: V_1.04–1.00Sb_0.96–1.00 (a = 0.4274(1)–0.4266(2) nm, c = 0.5464(2)–0.5448(4) nm). The binary antimonides with the NiAs structure dissolve the third component. V solubility in NiSb is within 3.5 at %. Ni dissolution in VSb is accompanied by partial Ni substitution for V and Ni incorporation into position 2d of space group P6₃/mmc, up to the composition V_0.84Ni_0.32Sb_0.84 (a = 0.42187(6) nm, c = 0.54000(9) nm).     

Phase equilibria in the Er-Si-B system

The phase diagram of the Er-Si-B system at 1070 K was mapped out using x-ray diffraction data. The system was shown to contain no ternary compounds. The mutual solubility of ErB₂ and ErSi_2-x was found to be no higher than 5 mol %. Hereafter, the structure type of a compound is specified in parentheses.     

Alloy-oxide equilibria in the system Pt-Rh-O

The composition of Pt-Rh alloys that co-exist with Rh₂O₃ in air have been identified by experiment at 1273 K. The isothermal sections of the phase diagram for the ternary system Pt-Rh-O at 973 K and 1273 K have been computed based on experimentally determined phase relations and recent thermodynamic measurements on Pt_1−X Rh _X alloys and Rh₂O₃. The composition dependence of the oxygen partial pressure for the oxidation of Pt_1−X Rh _X alloys at different temperatures, and temperature for the oxidation of the alloys in air are computed. The diagrams provide quantitative information for optimization of the composition of Pt_1−X Rh _X alloys for high temperature application in oxidizing atmospheres.     

Phase equilibria in the copper-cobalt-sulfur system

Phase equilibria in the copper-cobalt-sulfur system have been determined by means of silica tube techniques between 400° and 900°C. Throughout this interval the Cu_2?xS solid solution containing up to 11 wt % Co, coexists with cobalt sulfides (CoS₂, Co₃S₄, Co_1?xS, Co₉S₈, Co₄S₃). Co₃S₄ accepts up to 20.5 wt % copper and CoS₂ up to 12 wt % copper into solid solution. The increase in unit cell dimensions of Co₃S₄ and CoS₂ when copper substitutes for cobalt has also been determined.     

Phase equilibria and ordering in the erbia-zirconia system

The phase diagram for the system ZrO₂-Er₂O₃ was redetermined. At high temperatures, the system is dominated by wide regions of solid solution based on ZrO₂ and Er₂O₃ separated by a two-phase field which appears to extend to the solidus. The range of existence of these solid solution fields was determined using the precision lattice parameter method. A low-temperature (<1800° C) long-range ordering occurred between 20 and 90 mol % Er₂O₃, and three ordered phases were found: the first compound was present at 40 mol % Er₂O₃ and corresponds to the ideal formula Er₄Zr₃O₁₂ with rhombohedral symmetry (space group R¯3), is isostructural with UY₆O₁₂, and decomposes at about 1500° C into fluorite solid solution by an order-disorder process; the second ordered phase is formed at about 55 mol % Er₂O₃, its formula is close to Er₅Zr₂O_11.5, and it decomposes at about 1650° C into cubic solid solutions of the fluorite and C-type; the third compound is formed at 75 mol % Er₂O₃, its formula is Er₆ZrO₁₁, it has a wide homogeneity range, and it decomposes above 1700° C into a cubic solid solution of the C-type. Liquidus determination indicated the existence of a peritectic at 62 mol % Er₂O₃.This work is based on the Ph.D. thesis of C. Pascual, Madrid University, 1980.     

Thermodynamics and phase equilibria in the Ga---Sb system

The optimum values of the solution parameters of a multiparameter integral free-energy function have been determined using experimental data from the Ga---Sb system. The equation is represented as

ΔG^XS=x(1-x)[(a₁+a₂T+a₃T ln T)+x(a₄+a₅T+a₆T ln T)+x(1-x)(a₇+a₈T+a₉xT)]

The integral and the corresponding partial form of the free energy function have been found to be of use when interpreting the high temperature thermodynamic data, atomic interactions and phase equilibria in the Ga---Sb system.     

The nickel-rich corner of the Ni-Al-Ti system

Liquid-solid equilibria were studied in the nickel-rich corner of the Ni-Al-Ti system, using a combination of several experimental techniques, essentially differential thermal analysis (DTA) and all usual techniques of characterization. A modified version of the DTA technique, quench-interrupted DTA, was employed in order to establish the solidification paths. A projection of the liquidus surface is proposed and the nature of the monovariant lines is defined. One result is the occurrence of a ternary peritectic reaction between , and the liquid. Solidstate equilibria are determined for a temperature of 1250° C and the investigation has focused on the solid phase field.