The Al-Er-Mg ternary system Part I: Experimental investigation

Investigation of phase equilibria in the ternary system Al-Er-Mg has been carried out by means of differential thermal analysis (DTA), powder x-ray diffraction (XRD), light optical microscopy (LOM), scanning electron microscopy (SEM), and quantitative electron probe microanalysis (EPMA). The isothermal section at 400 °C has been established. An extended homogeneity region with Al substitution for Mg at a constant Er content has been found for (Mg_1−x Al _x )Er (0≤x≤0.78); a few other boundary binary phases give lower ternary solubility. A ternary compound, τ, of Al_66.7Er₁₀Mg_23.3 stoichiometry, has been found to exist in the isothermal section at 400 °C.     

Reassessment of Ni-Al and Ni-Fe-Al solidus temperatures

Solidus temperatures of the B2 NiAl phase have been determined by high-temperature differential thermal analysis for binary melt compositions Ni_xAl_100−x (45<x<57) and for ternary alloys Fe_yNi_50−yAl₅₀ (0≤y≤50). It was shown that the melting temperature of the stoichiometric Ni₅₀Al₅₀ phase is 1681 °C, which is 43 K higher than some literature data. The solidus line at the Ni-rich side of the Ni-Al phase diagram exhibits a steeper slope than that reported previously. Substituting Fe for Ni, the decrease of solidus temperature along the isoplethal section with 50 at.% Al of the ternary Ni-Fe-Al phase diagram exhibits a steep initial slope of −13 K/at.% Fe for small Fe-fractions, which changes into a nearly linear decrease with an average slope of −8.5 K/at.% Fe.     

Experimental study of ternary Fe-Gd-Mo phase diagram

The ternary system Fe-Gd-Mo was investigated at 1200 °C. A complete isothermal section is given, containing two ternary solid phases of composition Gd_1+n Fe_12−x−y Mo _x □ _y (□ is a vacancy), Gd₃Fe_29−x Mo _x and a liquid phase. Phase relations in Fe rich region are outlined in some detail. The ternary ThMn₁₂-type phase was found to possess an appreciable homogeneity range. The binary Fe-Gd compounds form solid solutions with several atomic percents of Mo. For the investigation x-ray powder diffraction followed by Rietveld refinement technique, scanning electron microscopy, and electron probe microanalysis were used.     

Experimental study of ternary Fe-Gd-Mo phase diagram

The ternary system Fe-Gd-Mo was investigated at 1200 °C. A complete isothermal section is given, containing two ternary solid phases of composition Gd_1+n Fe_12−x−y Mo _x □ _y (□ is a vacancy), Gd₃Fe_29−x Mo _x and a liquid phase. Phase relations in Fe rich region are outlined in some detail. The ternary ThMn₁₂-type phase was found to possess an appreciable homogeneity range. The binary Fe-Gd compounds form solid solutions with several atomic percents of Mo. For the investigation x-ray powder diffraction followed by Rietveld refinement technique, scanning electron microscopy, and electron probe microanalysis were used.     

Phase equilibria of the long-period stacking ordered phase in the Mg–Ni–Y system

Phase equilibria in the Mg-rich Mg–Ni–Y system at 300, 400 and 500 °C have been experimentally investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The results show that a long-period stacking ordered (LPSO) phase with 14H structure is thermodynamically stable in the Mg–Ni–Y system in a wide temperature range, but it dissolves varying from 492 to 559 °C depending on the alloy composition. The equilibrium 14H phase has a very limited solid solution range, and can be nearly regarded as a ternary stoichiometric compound with a formulae as Mg₉₁Ni₄Y₅. The isothermal sections of the Mg-rich Mg–Ni–Y system at 300, 400 and 500 °C have been finally established, and a eutectic reaction, Liquid ↔ α-Mg + 14H + Mg₂Ni, has been determined occurring at 492 °C with a liquid composition about Mg_84.8Ni_12.0Y_3.2.     

A ternary linear compound T2 and its phase equilibrium relationships in Mg–Zn–Nd system at 400 °C

The composition and the crystal structure of the phases in the alloys of Mg–Zn–Nd system at 400 °C have been studied by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and selected area electron diffraction (SAED) of transmission electron microscopy (TEM). The phase equilibrium relationships have been identified. As a result, a linear ternary compound T₂ phase has been identified. The general chemical formula of T₂ phase is (Mg, Zn)_11.5Nd and the crystal structure of that is C-centered orthorhombic. As the results, the other three ternary compounds T₁ phase, T₃ phase and T₄ phase have also been identified. The partial isothermal section of phase diagram of Mg–Zn–Nd system at 400 °C has been established.     

Alloying Behaviour of Zinc with Rare Earth Metals: The Er-Pr-Zn System

Zinc based alloys are among the most commonly used light alloys. To improve the knowledge of the ternary systems constituted by zinc with two lanthanides the isothermal section at 400 °C of the Er-Pr-Zn system was studied. Some selected samples at the Er:Pr ratio?=?1:1 were investigated by differential thermal analysis to draw the vertical section of the system. The experimental techniques used were x-ray powder diffraction, scanning electron microscopy, coupled with electron probe microanalysis and differential thermal analysis. No ternary compounds were found in the system. As regard the intermetallic phases, the (Er, Pr)Zn (Er, Pr)Zn₂, (Er, Pr)Zn_3, (Er, Pr)₁₃Zn₅₈ and (Er, Pr)₂Zn₁₇ solid solutions form in the full field of composition, while the ErZn₁₂, Pr₃Zn₁₁ and PrZn₁₁ compounds partially dissolve the third element. The metastable intermetallic binary phases ErZn₅, PrZn₅ and Er₆Zn₂₃ were not found either as ternary solid solutions or as binary compounds in the ternary Er-Pr-Zn system at 400 °C.     

Experimental Investigation of the Al-Fe-Nd System at 773 K

The phase diagram of Al-Fe-Nd is helpful for development of the magnetic and amorphous materials based on this system. The entire isothermal section of Al-Fe-Nd at 773 K was determined by means of x-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive analysis (EDX) and optical microscopy (OM). The existences of 12 binary compounds of the Al-Fe, Al-Nd and Fe-Nd systems were confirmed, and binary phases Al₂Nd and Fe₁₇Nd₂ demonstrated appreciable ternary solubility. The ternary compounds: τ₁-Al₁₀Fe₂Nd, τ₂-Al_8+x Fe_4?x Nd (0 < x < 0.7) and λ-Nd₃₀Fe_62?x Al_8+x (0 < x < 17) were confirmed in the present work. The isothermal section consists of 18 single-phase regions, 36 two-phase regions and 19 three-phase regions.     

The Yb–Zn–In system at 400 °C: Partial isothermal section with 0–33.3 at.% Yb

The phase relations in the ternary system Yb–Zn–In have been established for the partial isothermal section in the 0–33.3 at.% ytterbium concentration range at 400 °C, by researching of more than forty alloys. X-ray powder diffraction (XRPD), optical microscopy (OM) and scanning electron microscopy (SEM), complemented with energy dispersive X-ray spectroscopy (EDS), were used to study the microstructures, identify the phases and characterize their crystal structures and compositions. The phase equilibria of this Yb–Zn–In partial section at 400 °C are characterized by the presence of three extended homogeneity ranges, indium solubility in Yb₁₃Zn₅₈ and YbZn₂ and of zinc solubility in YbIn₂, and the existence of one ternary intermetallic compound, YbZn_1−xIn_1+x, x = 0.3. This new compound crystallizes in the UHg₂ structure type (space group P6/mmm), with a = 4.7933(5) Å, c = 3.6954(5) Å. The studied partial isothermal section has eight ternary phase fields at 400 °C.     

Experimental Phase Diagram of the Al-Er-Zr Ternary System

The phase diagram of the Al-Er-Zr ternary system at 773 K has been experimentally investigated by means of x-ray powder diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) with energy dispersive analysis (EDX). The existence of 13 binary compounds, i.e. Al₃Zr, Al₂Zr, Al₃Zr₂, AlZr, Al₃Zr₄, Al₂Zr₃, AlZr₂, AlZr₃, Al₃Er, Al₂Er, AlEr, Al₂Er₃ and AlEr₂ was confirmed. It is proved that the phases Al₃Zr₅ and Al₄Zr₅ do not exist at 773 K. The isothermal section consists of 16 single-phase regions, 29 binary-phase regions and 14 ternary-phase regions. The maximum solid solubility of Zr in Al₃Er, Al₂Er, AlEr, Al₂Er₃ and Er is about 9, 14, 4.5, 5.4, and 12 at.% Zr, respectively. No remarkable solid solubility could be found in the other compounds of this ternary system at 773 K. No ternary compound is found in the present work.     

The 400 °C Isothermal Section of the La-Co-Mg Ternary System

The isothermal section of the La-Co-Mg system at 400 °C was determined by characterization of about thirty ternary alloys synthesised by induction melting in sealed Ta crucibles and then annealed. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDXS) and x-ray powder diffraction (XRPD) were used to analyze microstructures, identify phases, measure their compositions and determine their crystal structures. Phase equilibria are characterized by the absence of ternary solid solutions and by the presence of three ternary phases. The existence and the crystal structure of the La_4?x CoMg_1 + x (τ₁, 0 ≤ x ≤0.15, cF96-Gd₄RhIn) were confirmed and its homogeneity region determined; the new phases La_23?x Co₇Mg_4 + x (τ₂, ?0.50≤ x ≤0.60, hP68-Pr₂₃Ir₇Mg₄) and ~La₃₈Co₅₅Mg₇ (τ₃, unknown crystal structure) were detected.     

The Fe–Ni–Al phase diagram in the Al-rich (>50 at.% Al) corner

The ternary Fe–Ni–Al phase diagram between 50 and 100 at.% Al was investigated by a combination of powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Ternary phase equilibria and accurate phase compositions of the respective equilibrium phases were determined within the isothermal section at 850 °C. The crystal structure of τ1 (Fe_4−xNi_xAl₁₀) and τ2 (Fe_2−xNi_xAl₉) was determined by means of single crystal X-ray diffraction. The decagonal quasi-crystalline phase q (Fe_4.9Ni_23.4Al_71.7) was found to be stable between 850 °C and 930 °C. All experimental data were combined to yield a ternary reaction scheme (Scheil diagram) involving 10 ternary invariant reactions in the investigated composition range, and a liquidus surface projection was constructed based on DTA results.     

Experimental Investigation of the Al-Fe-Gd System at 773 K

The phase equilibrium of the Al-Fe-Gd plays an important role of development of bulk amorphous alloys and magnetocaloric materials. The entire isothermal section of the phase diagram for Al-Fe-Gd ternary system at 773 K has been investigated by means of x-ray powder diffraction, scanning electron microscopy with energy dispersive analysis, and optical microscopy. The existences of 13 binary compounds for the Al-Fe, Al-Gd, and Fe-Gd binary systems were confirmed. The binary phases, i.e., Al₂Gd, Fe₂Gd, and α-Fe₁₇Gd₂ present appreciable ternary solubility. Three ternary compounds: τ₁-Al₁₀Fe₂Gd, τ₂-Al_8+x Fe_4-x Gd (0 ≤ x ≤ 2), and λ-Al_2?x Fe _x Gd (0.951 ≤ x ≤ 1.245) were determined. The isothermal section consists of 19 single-phase regions, 40 binary-phase regions, and 20 ternary-phase regions.     

Experimental Investigation of the Zn-Al-Sb System at 450 °C

An isothermal section of the Zn-Al-Sb ternary system at 450 °C has been established by equilibrating 11 samples of different compositions and phase identification by optical and scanning electron microscopy with energy dispersive spectroscopy, x-ray diffraction after quenching to room temperature. Five three-phase regions exist in the system at 450 °C. No ternary compound has been found. And, the compound AlSb with 2.1 at.% Zn can equilibrate with all phases in the system. Experimental results indicate that the solubility of Sb in α-Al phase is too limited to be detected. The SbZn, Sb₂Zn₃, and Sb₃Zn₄ phases, which have little Al solubility (at most 3.3 at.%), were observed in the system.     

Phase equilibria in Co−Al−Re ternary system at 1100 and 1300 °C

Isothermal sections of the Co?Al?Re ternary system at 1100 and 1300 °C were determined experimentally by electron probe microanalysis and X-ray diffraction. The results show that there are seven three-phase regions in the 1100 °C isothermal section and five three-phase regions in the 1300 °C isothermal section. The solid solubilities of αCo, εRe and CoAl increase a little with temperature increasing from 1100 to 1300 °C. The solubility of Co in compounds AlRe₂, Al₁₁Re₄ and Al₄Re is negligible, <1.5 at.%. And no ternary compounds are found.     

Solid-liquid phase equilibria in the Al-Fe-Si system at 727 °C

Different experimental techniques were combined to acquire better insight into the solid-liquid phase equilibria that tend to be established in the Al-Fe-Si ternary system at 727 °C under a pressure of 1 atm (101,350 Pa). Isothermal diffusion experiments followed by oil quenching were first carried out. The crystal nature, lattice parameters, morphology, and chemical composition of the different solid phases in equilibrium with the liquid were determined by x-ray diffraction, optical microscopy, scanning electron microscopy, and electron probe microanalysis. Points on the liquidus boundary were then positioned both directly by chemical analysis of liquid samples taken from solid-liquid mixtures equilibrated at 727 °C and indirectly by thermal analysis of Al-Si mixtures with controlled iron additions. On the one hand, it has been confirmed in agreement with currently accepted data that the compounds ϑAl₁₃Fe₄, αAl_7.4Fe₂Si (τ₅), and δAl₃FeSi₂ (τ₄) are in equilibrium at 727 °C with Al-Fe-Si liquids, the compositions of which have been refined. On the other hand, the authors have shown that the ternary compound γAl₃FeSi is in equilibrium at 727 °C with a ternary Al-Fe-Si liquid containing 10.5 to 16.5 at.% Si and 3.2 to 3.5 at. % Fe.     

The antimony-iron-niobium (Sb-Fe-Nb) system

Phase equilibria were established in the Nb-Fe-Sb ternary system for an isothermal section at 600 °C. Investigation of the phase relations was based on light optical microscopy, electron probe microanalysis, and X-ray diffraction experiments on arc-melted bulk alloys, which were annealed up to 1400 h. One ternary compound was observed: NbFeSb (MgAgAs type) without a significant homogeneity region at 600 °C. Except for NbFe_2−y , mutual solid solubilities at 600 °C were found to be very low, for example, <1 at.% Fe and <1 at.% Nb in the binary Nb antimonides and Fe antimonides, respectively. The binary Laves phase NbFe_2−y with the MgZn₂ type exhibits an extended homogeneity region dissolving at 600 °C up to 7 at.% Sb in the ternary without change of its structure type.     

Phase Equilibria in the Al-Zr-Nd System at 773 K

The isothermal section of the phase diagram of the Al-Zr-Nd ternary system at 773 K has been investigated by means of x-ray powder diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM) for the first time. The existences of 14 binary compounds i.e. Al₃Zr, Al₂Zr, Al₃Zr₂, AlZr, Al₃Zr₄, Al₂Zr₃, AlZr₂, AlZr₃, α-Al₁₁Nd₃, Al₃Nd, Al₂Nd, AlNd, AlNd₂ and AlNd₃ were confirmed. The isothermal section consists of 17 single-phase regions, 31 binary-phase regions and 15 ternary-phase regions. No binary compound is found in the Nd-Zr binary system. No ternary compound is found in the present work. None of the phases in this system reveals a remarkable solid solution at 773 K.