The Equilibrium Phase Diagram for the Tm ― Mn ― B System

X-ray diffraction has been applied to the component interaction study in the ternary Tm Mn B system, and the 1070 K isothermal section of the phase diagram has been constructed. The ternary boride TmMnB₄ is confirmed as present, which has the YCrB₄ structure type (space group Pbam, a = 0.5868-0.5894 nm; b = 1.1320-1.1370 nm; c = 0.3368-0.34018 nm). The lattice parameter variation indicates that the ternary boride has only a narrow homogeneity region, which is in the direction of higher manganese contents. There are no solid solutions based on binary compounds in the Tm Mn B system.     

Phase Diagram of the Al ― Rh System

Phase equilibria in the Al Rh system over the range 15-50 at.% Rh were investigated by the methods of scanning electron microscopy, x-ray diffraction and electron-probe microanalysis.     

Regularities of Reactive Diffusion and Phase Formation in Ni ― Bi,Ni ― Zn,and Co ― Zn Binary Systems

Intermetallide layers enriched in bismuth or zinc are the first to grow in the Ni Bi, Ni Zn, and Co Zn reaction pairs. It is not found that high-symmetry phases of equiatomic composition are formed. There is not even a weak correlation between the rate of layer growth and the width of the homogeneity region for these intermetallic compounds. The main factors that determine the formation sequence for the intermetallic layers are the differences in melting point and atomic radius between the components, as well as the crystal structures of the intermetallides. The Kirkendall effect cannot be observed in the growing intermetallic layers. In that case, there is no physical basis for determining integrated diffusion coefficients.     

Phase Equilibria in the Lu ― V ― B System and the Structure of the New Boride Lu1.34V1.66B6

X-ray diffraction data have been used to construct the 1070 K isothermal section of the Lu V B phase diagram. The solubility of VB₂ in LuB₂ attains 5 at.% (lattice parameters of the (Lu, V)B₂ phase of the limiting composition with the AlB₂ structure are a = 0.3238(1), c = 0.3689(1) nm). A new ternary boride has been discovered, Lu_1.34V_1.66B₆, which belongs to the Y₂ReB₆ structure type (space group Pbam, a = 0.8947(8), b = 1.1273(7), c = 0.3381(2) nm, F _hkl > 4(F), 2thetav;_max = 72.76°, N _hkl = 379, R _F = 0.0617, R _w = 0.0653) and is characterized by a statistical distribution of the Lu and V atoms in one of the structure positions.     

Physico-Chemical Investigation of Component Interactions of the Si ― Al ― O ― N ― Ti System in the Region Si3N4 ― AlN ― Al2O3 ― SiO2 ― TiN ― TiO2. Part 1. Subsystems Si3N4 ― Al2O3, Si3N4 ― TiN,and Al2O3 ― TiN

Using the methods of differential thermal and x-ray diffraction analysis an investigation was made of component reactions in the Si Al O N Ti system, particularly between the compounds Si ₃N₄ Al₂O₃, Si₃N₄ TiN, and Al₂O TiN under conditions approximating those used in the hot pressing of composites. It was established that in the reaction of Si₃N₄ with Al₂O₃, -sialon, SiO₂, AlN, and the intermediate reaction products (mullite and X-phase) are formed. In the reaction of Si₃N₄ with TiN, as a result of the decomposition of Si₃N₄ at 1650-1900°C titanium disilicide is produced, which forms eutectics with free silicon and residual TiN at 1320 and 1280°C, respectively. The reaction of Al₂O₃ with TiN similarly leads to the formation of a eutectic between Al₂O₃ and spinel at 1850°C. The presence of eutectic liquids in the specimens after sintering promotes densification of the material, and improves certain of its mechanical properties.     

Solidus Surface and Phase Equilibria in Al2O3 ― ZrO2 ― La2O3 Alloy Crystallization

The projection of the solidus surface in the phase diagram for the Al₂O₃ ZrO₂ La₂O₃ system on the plane of a concentration triangle has been constructed, which consists of seven isothermal three-phase fields corresponding to three nonvariant equilibria of eutectic type and four nonvariant equilibria of peritectic type, as well as four lineated surfaces for the end of crystallization in the binary eutectics. The highest temperature on the solidus surface is 2710°C, and the lowest is 1665°C. No ternary phases and appreciable areas of solid solution are observed. Data on the bounding binary systems, liquidus and solidus surfaces have been used to construct the phase-equilibrium diagram together with a scheme for the reactions in equilibrium crystallization in the Al₂O₃ ZrO₂ La₂O₃ system.     

Phase Diagrams of the Zr–Si–RE (RE=La and Er) Ternary Systems at 773?K (500?°C)

The isothermal sections of the phase diagram of the Zr–Si–RE (RE=La and Er) systems at 773 K (500 °C) have been investigated using X-ray power diffraction (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) with the aid of metallographic analysis. The existences of 10 binary compounds, namely ZrSi₂, α-ZrSi, α-Zr₅Si₄, Zr₃Si₂, Zr₂Si, RESi₂, RESi_2–x , RESi, RE₅Si₄, and RE₅Si₃ have been confirmed in the Zr–Si–RE (RE=La and Er) systems, respectively. As for the reported binary compound RE₃Si₂, only La₃Si₂ has been observed in the Zr–Si–La system, whereas Er₃Si₂ was not found. No binary compound was found in the Zr–RE binary systems, and no ternary compound was found in the current ternary systems. None of the phases in Zr–Si–La system reveals a remarkable solid solution at 773 K (500 °C). However, the maximum solid solubility of Zr in Er, Er₅Si₃, Er₅Si₄, ErSi, ErSi_1.67, and ErSi₂ is determined to be approximately 12.0 at. pct, 2.4 at. pct, 3.0 at. pct, 3.3 at. pct, 2.2 at. pct, and 1.8 at. pct, respectively. The maximum solid solubility of Er in ErSi₂ is approximately 1.8 at. pct. No remarkable solid solubility of the elements in any of the other phases has been observed.     

Thermodynamics of Component Interactions in Liquid Alloys of the Ternary Systems Ge(Al,Si) ― Ga ― Gd

The concentration dependence of the integral enthalpy of mixing in liquid alloys of the ternary systems Ge(Al, Si) Ga Gd at 1760 K, determined by the method of isoperibolic calorimetry and calculated using the surrounded atom model, was analyzed. Good agreement between H values obtained by both methods is noted. It was established that the interaction of gadolinium with components of the adjoining binary systems, which are characterized by the presence of intermetallic compounds, have a defining effect on the thermodynamics of alloy formation in the ternary systems Ge(Al, Si) Ga Gd.     

Study of Phase Formation Processes in the Systems Li ― N,Si3N4 ― Li3N,Si3N4 ― Li3N ― Y2O3

We have studied phase formation processes in the systems Li N and Si₃N₄ Li₃N. By nitriding lithium powder at temperatures of 400-600°C, we obtained lithium nitride Li₃N with a composition approaching stoichiometric. In the system Si₃N₄ Li₃N in the temperature range 300-1300°C, the ternary compounds Li₈SiN₄ (500°C), Li₅SiN₃, Li₂SiN₂ (900°C), and LiSi₂N₃ (1300°C) are formed. The studied properties of the hot-pressed composite material of the system Si₃N₄ Li₃N Y₂O₃ allow us to provisionally assign it to the class of solid electrolytes.     

Nitriding Powders in the System SiO2 ― Al2O3 ― C

Chemical and x-ray analysis methods are used to study features of carbothermal reduction and simultaneous nitriding of a powder mixture of crystalline SiO₂ (α-quartz) and amorphous SiO₂ (Aerosil). It is established that the use of amorphous SiO₂ leads to accelerated formation of SiC and a shift in the direction of nitriding towards AlN formation. It is also shown that both phases are the solid solutions SiC ― AlN and AlN ― SiC.     

Phase Formation and Structure of Bronze ― Iron ― Graphite Composite Powder Material during Hot Forming

Copper tin iron graphite material prepared by hot forming is studied. It is established that on heating billets to 850°C Cu Sn alloy forms and there is no copper or tin in pure form after heating. The Fe Sn phase does not even form locally. Bronze grains have a banded relief that is connected with formation of a large number of twins and additional dislocations in Cu(Sn) solid solution. This structural inhomogeneity facilitates material strengthening and high operating properties.     

Mechanico-Chemical Synthesis,Structure and Properties of Alloys Based on the System Ti ― Al

The kinetics of structure and phase formation in Ti Al and Ti Al Sc alloy powders in the process of mechano-chemical synthesis from elemental powders was investigated. It was established that the formation of microdimensional x-ray amorphous composite particles with nanodimensional structural components occurs. It was shown that in consolidation of the mechanically alloyed powders by hot isostatic pressing structural heredity is realized, and that the materials produced have unusually high microhardness compared to that of similar cast alloys. This is characteristic of nanostructured materials. In addition to high hardness the materials are characterized by high work of plastic deformation at room temperature. Microalloying the alloy powders with scandium has a complex positive effect on the strength properties of the hot pressed materials, due to the formation of a dispersion hardened microstructure with purified nanodimensional grains.     

Chromium ― Copper System: Adhesion Characteristics,Doping, the Structure of Phase Boundary and Composites

The adhesive characteristics and the formation of phase boundaries in the Cr Cu system in a vacuum of (2-4)·10^–3 Pa in the temperature range 1100-1300°C have been studied. The microstructure of composites (50:50 by mass) made by copper impregnation of porous samples of Cr electrolytic powders and Cr obtained by calcium hydride reduction. The effect of Cr, Fe, Co, Ni, Si additions on above characteristics has been investigated.     

Interactions in the Al2O3 ― ZrO2 ― La2O3 System at 1250 and 1650°C

Triangulation has been determined for the Al₂O₃ ZrO₂ La₂O₃ system, and 1250 and 1650°C isothermal sections of the phase diagram have been constructed. The LaAlO₃ La₂Zr₂O₇ section is quasibinary, while the LaAlO₃ T-ZrO₂ and La₂O₃ ·11Al₂O₃ T-ZrO₂ ones are partially quasibinary. The triangulation of the ternary system is based on ZrO₂ and a phase containing it. No ternary compounds or regions of ternary solid solutions have been identified.     

Effect of Mineralizing Agent on the Phase Composition of Nanocrystalline Powder in the System ZrO2 ― Y2O3 ― CeO2

The effect of mineralizing agent (AlF₃) on microstructural rebuilding and phase transformation that occurs during heat treatment in the range 600-1000°C for powder of the composition ZrO₂ 7 mole% CeO₂ 1 mole% Y₂O₃ is studied. The original nanocrystalline powder is prepared by high-temperature hydrolysis and sol-gel technology. It is established that during heat treatment there is decomposition of the solid solution based on T-ZrO₂ by a eutectoid reaction with formation of M-ZrO₂ and Ce₂Zr₃O₁₀. The compound Ce₂Zr₃O₁₀ is retained under these conditions at 1000°C. Anisotropic crystals of different chemical composition (M-ZrO₂, Ce₂Zr₃O₁₀, -Al₂O₃) form within the sintered matrix of a solid solution based on T-ZrO₂.     

Preparation of Y-Zr-Hf,Y-Zr-Nb Ternary Diffusion Couples and Phase Diagrams Determination

Work has been done in preparing ternary diffusion couple containing one rare earth element.Though rareearth is highly reactive,we have successfully prepared two ternary diffusion couples containing yttrium by meansof special technique.By using electron microprobe analysis(EMPA),the two isothermal sections of Y-Zr-Hfand Y-Zr-Nb ternary systems at 1273K have been determined.The section of Y-Zr-Hf system consists ofthree one-phase regions,three two-phase regions and one three-phase region.And that of Y-Zr-Nb systemconsists of two one-phase regions and one two-phase region.The effeet of some factors on EMP measuring ac-curacy was also discussed.     

Effect of Impurities on the Phase Composition and Properties of a New Alloy of the Al–Y–Er–Zr–Sc System

Metallurgist - A comparative study is provided for the effect of Si and Fe impurities in relation to their concentration in the structure, phase composition, and mechanical properties of alloy...