Phase equilibria in the Ag2/3Zn1/3-Te system

Using differential thermal analysis, X-ray diffraction analysis and composite phase diagrams, the most probable form of the polythermal section Ag_2/3Zn_1/3-Te of the ternary system Ag-Zn-Te has been deduced. It was found to be non-quasi-binary with 14 phase fields and four isotherms of the non-variant equilibria. It is suggested that a phase with composition Ag₂ZnTe₂, stable at temperatures above 515°C, is formed.     

Constitution of Ti–Al–Ru system

Abstract

The constitution of the Ti–Al–Ru system has been studied in detail. Metallography, X-ray diffraction, electron microscopy, and X-ray spectroscopy have been used to establish the phase diagram between 17 and 37 at.-%Al and 1 and 29 at.-%Ru in the temperature range 1250–770°C. Ternary isothermal sections within the range of investigation and selected phase composition data are presented and phase relationships are discussed. Results show only a small solubility (< 1at.-%) of ruthenium in Ti₃Al and TiAl which are involved in equilibria with a ternary intermetallic compound.

MST/963     

Phase equilibria in the system CdO-B2O3-SiO2 at 800° C

Phase equilibria in the system CdO-B₂O₃-SiO₂ were investigated at 800° C using X-ray powder diffraction techniques. The binary phases reported previously were confirmed, but no ternary phases were found. Solid solution effects were investigated for the primary and binary phases by comparison of patterns; no solid solutions were detected. The relationship of the phase diagram to the composition of photoconductive oxide glasses is discussed and suggestions are made of possible mechanisms responsible for the photoelectric effects.     

Stoichiometric NbTiAl_3 (γ1 Phase) Alloy in Ti-Al-Nb Ternary System

The microstructure and phase constitution in stoichiometric NbTiAl3 (γ1 phase) alloy treated at 1000℃ were examined by metallography and X-ray diffraction. The alloy microstructure is mainly γ1 phase containing η second phase [(Ti,Nb)Al3] less than 1%. DTA analysis shows no phase transformation from room temperature to 1200℃. In the diffusion couple of NbTiAl3 with 7-TiAl compound, clear phase boundary and composition jump exist between γ1 and γ phase.These results further confirm the existence of γ1 single phase at 1000℃ in Ti-Al-Nb ternary system.     

Experimental investigation and thermodynamic calculation of the Ga–Sb–Zn phase diagram

Phase equilibrium of ternary Ga–Sb–Zn system was investigated by applying CALPHAD method and using literature thermodynamic data for constitutive binary systems. The liquidus surface and isothermal section at 673 K were calculated. Calculated results were verified experimentally on the alloys samples with the compositions corresponding to the characteristic vertical sections: SbZn (1:1)–Ga; GaZn(1:1)–Sb; and GaSb(1:1)–Zn. Phase transitions temperatures were determined by differential thermal analysis and differential scanning calorimetry. Microstructure and phase composition investigation were investigated by using scanning electronic microscopy with energy dispersive spectrometry. The experimental and analytical results showed good agreement, concerning the temperatures of phase transitions and phase compositions of alloys concerned.     

X-ray diffraction study of the NaF-LiF-NdF3 eutectic in the liquid and solid states

The ternary eutectic alloy with the composition 33 mol % NaF + 53 mol % LiF + 14 mol % NdF₃ has been studied in the liquid and crystalline states using differential thermal analysis and X-ray diffraction at room and high temperatures. The results demonstrate that the alloy undergoes no phase transformations below its melting point: the only phases identified with certainty are NaF, LiF, and NaNdF₄. The melt contains complex microgroups differing in cation composition. Analysis of structural models for the melt indicates that there is no dense noncrystalline packing of the fluorine anions, in contrast to what was observed previously in the eutectic NaF-LiF-LaF₃ melt.     

Phase equilibria and glass formation in the AsSe-MnSe system

The phase equilibrium in the AsSe-MnSe system has been studied using physicochemical characterization techniques (differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements), and its phase diagram has been mapped out. The system is shown to be a pseudobinary join of the ternary system Mn-As-Se. At AsSe: MnSe = 1: 1, the system contains a compound of composition MnAsSe₂, which melts incongruently at 750°C. The glass-forming region extends to 15 mol % MnSe. We have examined the crystallization behavior of the glasses. Solid AsSe dissolves up to 2 mol % MnSe, and solid MnSe dissolves up to 2.5 mol % AsSe.     

Phase equilibria in the system CdO-B2O3-GeO2 at 800°C

Phase equilibria in the system CdO-B₂O₃-GeO₂ were investigated at 800° C using X-ray powder diffraction techniques. The binary phases reported previously as produced by solid-state reactions were confirmed and, in addition, a new one CdO·2GeO₂ was found. The ternary phase diagram was solved and a new phase CdO·B₂O₃·GeO₂ was discovered. X-ray powder data are given for both these new phases. Solid solution effects were investigated for the primary and binary phases by comparison of patterns; no solid solutions were detected. The relationship of the phase diagram to the composition of photoconductive oxide glasses is discusssed in the light of previous suggestions made of possible mechanisms responsible for the photoelectric effects.     

Phase Relations in TiAl+Nb System

The microstructures and phases of ternary TiAl+Nb alloys containing 50-60 at.-%Al, 0-21 at.-%Nb have been studied using transmission electron microscopy (TEM) and X-ray powder diffraction. The phases present in the alloys and their distribution were found to be a sensitive function of composition. The phase relations between γ-TiAl and γ1 (a new ordered ternary intermetallic compound based on γ-TiAl) were determined. Essentially single γ phase was determined for alloys with relativety low Nb content (≤10 at.-%Nb). the γ1 phase was determined to exist in the composition range containing higher Nb contents (15-21 at.-%Nb). Between γ and γ1 phases, with intermediate Nb contents there is a transitional phase γ1 (a superstructure of γ-TiAl). As for the influence of Al concentration on the phase relations. the γ1 phase was inclined to form in the alloys with relatively high Al contents. The ordering transformation of γ, to γ1 is a continuous ordering process and the transition may be second order.     

Experimental investigation and thermodynamic description of the Mg–Y–Zr system

The Mg–Y–Zr system was studied via experimental investigation and thermodynamic modeling. Four diffusion couples and four key alloys of the Mg–Y–Zr system at 500 °C were prepared. The phase relations of the Mg–Y–Zr system were investigated by means of X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. No ternary compound was found at 500 °C. The solubility of (αZr) in the Mg–Y intermetallics, i.e., Mg₂₄Y₅, Mg₂Y and MgY, was determined to be negligible. The differential scanning calorimetry measurement was performed on the Mg–Y–Zr alloys to obtain the phase transition temperature. The present thermodynamic calculations of the Mg–Y–Zr system matched well with the experimental data. The presently established Mg–Y–Zr phase diagram can offer a better understanding of the recent processing technique of creep-resistant magnesium alloys.     

Effect of Rare Earth and Transition Metal Elements on the Glass Forming Ability of Mechanical Alloyed Al–TM–RE Based Amorphous Alloys

The present work aims to compare the amorphous phase forming ability of ternary and quaternary Al based alloys(Al86Ni8Y6, Al86Ni6Y6Co2, Al86Ni8La6 and Al86Ni8Y4.5La1.5) synthesized via mechanical alloying by varying the composition, i.e. fully or partially replacing rare earth(RE) and transition metal(TM) elements based on similar atomic radii and coordination number. X-ray diffraction and high resolution transmission electron microscopy study revealed that the amorphization process occurred through formation of various intermetallic phases and nanocrystalline FCC Al. Fully amorphous phase was obtained for the alloys not containing lanthanum, whereas the other alloys containing La showed partial amorphization with reappearance of intermetallic phases attributed to mechanical crystallization. Differential scanning calorimetry study confirmed better thermal stability with wider transformation temperature for the alloys without La.     

Effect of Mo and Ti on the microstructure and microhardness in AlCoFeNiMoTi high entropy alloys prepared by mechanical alloying and conventional sintering

In this investigation, the synthesis of equiatomic AlCoFeNi, AlCoFeNiMo, AlCoFeNiTi, and AlCoFeNiMoTi high entropy alloys, fabricated by mechanical alloying and conventional sintering processes is presented aiming to elucidate the effect of Mo and Ti additions on the properties of the AlCoFeNi base system. X-ray diffraction studies revealed that after 15 h of milling, only BCC and FCC structures were formed. It was also found that by increasing the crystallite size after sintering, phase transformations and composition variations were observed for all the systems studied but BCC and FCC structures prevailed. Further, the addition of the different alloying elements had a significant effect on the microhardness of the HEAs and particularly, the addition of Mo and Ti to form the AlCoFeNiMoTi system presented the highest value of 894 HV0.2. Finally, it was also found that Mo- containing alloys presented considerable porosity.     

Effects of Au/Cu ratio and gallium content on the low-temperature age-hardening in Au-Cu-Ga alloys

The effects of Au/Cu ratio and gallium content on the low-temperature age-hardening were examined in Au-Cu binary and Au-Cu-Ga ternary alloys by hardness testing, X-ray diffraction and differential thermal analysis. In alloys in which the Au/Cu ratios greatly deviated from the equiatomic one, age-hardenability at 37 °C significantly decreased. Gallium addition lowered the liquidus temperature and increased the age-hardening rate. It is considered that the diffusion rate of the constituents increased with lowering of the liquidus temperature, and that consequently, gallium addition improved the age-hardenability.     

Growth and electrical properties of AgGaS2 thin films

Polycrystalline and amorphous thin films of AgGaS₂ were grown by flash evaporation for the first time. From a detailed investigation of the growthconditions it was possible to derive the first so-called structural phase diagram of a ternary chalcopyrite compound. In addition, the crystallization behaviour of amorphous films in a second heat treatment step was studied extensively. The crystal structures and chemical composition were analysed by X-ray diffraction, thermogravimetry and atomic absorption spectroscopy. The films were characterized by electrical and photo-electrical measurements.     

Combinatorial Synthesis and High-Throughput Characterization of Microstructure and Phase Transformation in Ni–Ti–Cu–V Quaternary Thin-Film Library

Ni–Ti–based shape memory alloys (SMAs) have found widespread use in the last 70 years, but improving their functional stability remains a key quest for more robust and advanced applications. Named for their ability to retain their processed shape as a result of a reversible martensitic transformation, SMAs are highly sensitive to compositional variations. Alloying with ternary and quaternary elements to fine-tune the lattice parameters and the thermal hysteresis of an SMA, therefore, becomes a challenge in materials exploration. Combinatorial materials science allows streamlining of the synthesis process and data management from multiple characterization techniques. In this study, a composition spread of Ni–Ti–Cu–V thin-film library was synthesized by magnetron co-sputtering on a thermally oxidized Si wafer. Composition-dependent phase transformation temperature and microstructure were investigated and determined using high-throughput wavelength dispersive spectroscopy, synchrotron X-ray diffraction, and temperature-dependent resistance measurements. Of the 177 compositions in the materials library, 32 were observed to have shape memory effect, of which five had zero or near-zero thermal hysteresis. These compositions provide flexibility in the operating temperature regimes that they can be used in. A phase map for the quaternary system and correlations of functional properties are discussed with respect to the local microstructure and composition of the thin-film library.     

Silicon effects on formation of EPO oxide coatings on aluminum alloys

Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al–Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys (∼ 17% Si) and hypoeutectic 319 alloys (∼ 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms.     

Phase investigations in the silver-gallium-sulphur system

The binary join Ag₂SGa₂S₃ and some supplementary compositions in the ternary system AgGaS were examined by differential thermal analysis and X-ray diffraction. From the experimental results the phase diagram of the Ag₂SGa₂S₃ system was constructed. Besides the well-known chalcopyrite analog AgGaS₂ two additional compounds of composition Ag₉GaS₆ and Ag₂Ga₂₀S²₃₁ were established, both being dimorphic. Outside the binary section only one new phase, a Ag-containing rhombohedral modification of gallium sulphide, GaS:Ag(3R), could be found. Crystal data for all phases investigated are given. Ag₉GaS₆ is a representative of a group of possible superionic conductors with icosahedral structure.     

New phase Ti3Co2Si in the Ti-Co-Si ternary system at 1100℃

1. IntroductionIt is reported that there are seven ternary compounds in the Ti--Co-St systems which are CoTiSi(E), Co4Ti4Si7(V), Co3TiSiZ(G"), Co3TiZSi(G'),ColoTi6Siv(G) and Co,TiSill]. In constitution of theCo--Ti-St 1100'C isothermal section, a new phase withthe composition of Ti3CoZSi was found. In the beginning, this phase was found in several alloys to have acomposition that is differeds from known binary andternary phases from the WDX composition microanalysis. Latter it …     

Alloy design and microstructure of a biomedical Co-Cr alloy

Two wrought Co-Cr alloys for dental and surgical implant and equipment applications were designed and their microstructures and hot workability determined and compared to a current dental alloy SC-H. The chemical composition of the alloys was selected with regard to the general requirements for biomedical alloys and the general principles of alloying theory. A phase-control law originally developed for nickel-base superalloys, PHACOMP, was utilized in order to avoid the formation of topologically close-packed (tcp) phases and to ensure the ductility and workability of the alloy. The alloys were cast using a vacuum induction melting technique which was found to allow a fairly good chemical composition control of the alloys. Hot forging of the as-cast alloys confirmed their good workability. Optical metailography showed the as-cast alloys to have a dendritic structure with some spherical carbide particles in the interdendrite regions. In contrast, the dental alloy SC-H in the as-cast condition had continuous carbide along the grain boundaries which impaired the ductility and prevented hot forging of this alloy die to cracking of the specimens. X-ray diffraction analysis showed that both alloys I and II have the fcc-Co matrix and Cr₂₃C₆ type carbide particles. No tcp phases were observed.     

Preparation and investigation of a glass in the system Al2O3–SiO2–CaO for dental applications

The aim of this work was the synthesis and investigation of the thermal and mechanical properties of a glass in the Al₂O₃–SiO₂–CaO–F system, to be used in dental field. Following the synthesis, the glass powder was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The thermal expansion coefficient was obtained by employing dynamic mechanical analysis (DMA). The mechanical characterization of the glass employed the determination of Young modulus and compressive strength. The crystallization process was investigated using differential thermal analysis (DTA) and XRD. The results allowed us to affirm that the characteristics of this glass, in comparison with the tooth hard substances and other commonly employed inorganic dental materials, recommend it for further utilization in the dental field.