Phase diagram of the Al–Er–Mo ternary system at 873 K

The phase relationship in the Al–Er–Mo ternary system at 873 K has been investigated based on the equilibrated method mainly by means of X-ray powder diffraction and scanning electron microscopy. The existence of 10 binary compounds and two ternary compounds has been confirmed. The results present that the isothermal section at 873 K is governed by 15 single-phase regions, 29 two-phase regions and 15 three-phase regions. By using the phase-disappearing method, Al₈Mo₃ has a narrow homogeneity range (from 72 to 73 at% Al), while the homogeneity range of AlMo₃ is from 21% to 28.5% at% Al. Also, the maximum solubility of Al in Mo is about 16 at%.     

Ternary compounds and isothermal section in Lu–Fe–Ga ternary system at 773 K

The isothermal section of the Lu–Fe–Ga ternary system at 773?K was investigated and constructed based on X-ray powder diffraction analysis. Thirteen binary compounds, Lu₂Fe₁₇, Lu₆Fe₂₃, LuFe₂, LuGa₃, LuGa₂, Lu₃Ga₅, LuGa, Lu₃Ga₂, Lu₅Ga₃, Fe₃Ga, Fe₆Ga₅, Fe₃Ga₄, FeGa₃, nine ternary solid solutions, T₁-LuFe_2–1.43Ga_0–0.57, T₂-LuFe_1.34–0.92Ga_0.68–1.08, T₃-LuFe_0.52–0.26Ga_1.48–1.74, T₅-LuFe_2.04–1.72Ga_0.96–1.28, T₆-Lu₆Fe_23–21.4Ga_0–1.6, T₇-Lu₂Fe_17–14.5Ga_0–3.5, T₈-Lu₂Fe_12.9–8.1Ga_4.1–8.9, T₉-LuFe_6.8–5.5Ga_5.2–6.5, T₁₀-LuFe_5.2–4.5Ga_6.8–7.5, and two ternary compounds, T₄-LuFe_2.35Ga_0.65 and T₁₁-Lu₂FeGa₈ have been confirmed. The structures of the five new ternary compounds or solid solution T₂, T₃, T₄, T₅ and T₈ are determined by Rietveld refinement method.     

Phase relationships in the Co–Pt–Nd ternary system at 773 K

The isothermal section of the Co–Pt–Nd system at 773 K was constructed in the whole concentration range by using X-ray diffraction, scanning electron microscopy, and energy dispersion spectroscopy techniques. Twenty-two single-phase regions (including solid solution regions of the binary compounds) were determined; 41 two-phase regions and 20 three-phase regions were identified to exist at this isothermal section. No new binary and ternary phases were found.     

Investigation on the 773 K isothermal section of Dy–Ni–Si ternary phase diagram by X-ray powder diffraction

The 773 K isothermal section of the Dy–Ni–Si ternary system was investigated and constructed by X-ray powder diffraction in this paper. Eighteen ternary phases (DyNiSi, DyNi₂Si₂, DyNiSi₂, Dy₂Ni₃Si₅, DyNiSi₃, Dy₂NiSi₃, Dy₃Ni₆Si₂, DyNi₁₀Si₂, Dy₄NiSi₇, DyNi₂Si, DyNi₅Si₃, DyNi₄Si, Dy₃NiSi₂, DyNi₆Si₆, Dy₈Ni₃₁Si₁₁, Dy₃Ni₂Si₄, Dy₄Ni₅Si and Dy₉Ni₂Si₁₄) were confirmed to exist in this work. In those ternary phases, Dy₉Ni₂Si₁₄ is a new phase, Dy₂NiSi₃ and Dy₄NiSi₇ have solid solution phenomena and the solid solution ranges are Dy_33.3Ni_14.7–18.7Si_52–48 and Dy₄Ni_0.3–1.2Si_7.7–6.8, respectively. We constructed 14 two phase regions and 52 three phase regions in the Dy–Ni–Si ternary phase diagram at 773 K. Because the phase relation is not very clear between 66.7 and 50 Si at.% in the Dy–Si binary system, we use dot lines to estimate tentative phase regions in this region.     

Phase relationships in the Gd–Co–Al ternary system at 500°C

The phase relationships in the Gd–Co–Al ternary system at 500°C have been investigated mainly by X-ray diffraction, scanning electron microscopy, and energy dispersion spectroscopy. The existence of two ternary compounds GdCo_0.74Al_1.26 and Gd₂Co₂Al has been confirmed. Twenty-two single-phase regions (including solid solution regions of the binary compounds), 43 two-phase regions, and 22 three-phase regions were found to exist at this isothermal section. In this work, no new binary or ternary phase was found.     

Magnetically induced phase separation in the Co–Cr binary system

Direct evidence of phase separation in the Co-rich corner of the Co–Cr binary system, the transformation of high-temperature FCC α-Co into a ferromagnetic α_f phase and a paramagnetic α_p phase, has been experimentally obtained by using diffusion couple technique, scanning electron microscopy with energy dispersion analysis of X-ray (SEM-EDX), analytical transmission electron microscopy, optical microscopy and X-ray diffraction. Thermodynamic calculation, on the basis of the presently obtained phase equilibrium data, has verified that this phase separation arises from magnetic ordering, and that a similar phase separation appears in the HCP phase below 469°C which is transformed into a ferromagnetic ε_f phase and a paramagnetic ε_p phase. It is therefore concluded that magnetically induced phase separation must be responsible for the microscopic composition modulation of Cr in the CoCr thin film magnetic recording media.     

Thermal conductivity of liquid rubidium in the interval of 312–873 K

The thermal conductivity λ and the thermal diffusivity a of liquid rubidium were measured by the laser flash method in the temperature interval from the melting point up to 873 K. The measurement error was 4–6%. The data of this paper were compared with the results of other authors. Approximation equations and the table of reference values for the temperature dependence of λ and a have been obtained. The dependence of the Lorentz number on temperature has been calculated.     

The absorption of sulfur dioxide in the terahertz range at temperatures of 300–1200 K

The rotational spectrum of the absorption of the main isotope of sulfur dioxide (³²S¹⁶O₂), which corresponds to the terahertz range of electromagnetic waves, namely 1–250 cm^?1 (0.1–10 THz), is studied. The consideration covers rotational transitions within all vibrational states whose Hamiltonian parameters are known from the literature: (000-000), (010-010), (100-100), (001-001), (020-020), (110-110), (011-011), (030-030), (120-120), (200-200), (002-002), (130-130), (103-103), (301-301), (101-101), (021-021), (210-210), (111-111), (201-201), (003-003), and (131-131). As a result, the absorption coefficient of ³²S¹⁶O₂ is calculated for a broad temperature range (300–1200 K) and the contribution of the rotational band of each vibrational state to the total absorption coefficient is evaluated.     

Growth and physical properties of the decagonal Al–Cu–Co quasicrystal grown from the ternary melt

Large faceted single-grain quasicrystals of the approximate composition Al_63.2Cu_19.5Co_17.3 and with a high degree of structural perfection are obtained through the slow cooling of a ternary melt with initial composition Al₆₅Cu₂₉Co₆. X-ray diffraction patterns of crushed single-grain samples are exceptionally sharp, indicating a high degree of structural order, with no evidence of secondary phases. Transmission electron micrographs also reveal sharp diffraction patterns in the even-n layers but diffuse scattering in the odd-n layers. Temperature-dependent magnetization, electrical resistivity and specific heat are measured using bars cut perpendicular and parallel to the c axis and show diamagnetic behaviour: γ?≈?0.5?mJ?mol^?1?K^?2, ρ _c(2?K)?≈?52?μΩ?cm and ρ _q(2?K)?≈?283?μΩ?cm.     

Solidification mechanism transition of liquid Co–Cu–Ni ternary alloy

We report a solidification mechanism transition of liquid ternary Co₄₅Cu₄₅Ni₁₀ alloy when it solidifies at a critical undercooling of about 344 K. When undercooling at ΔT<344 K, the solidification process is characterized by primary S (Co) dendritic growth and a subsequent peritectic transition. The dendritic growth velocity of S (Co) dendrite increases with the rise of undercooling. However, once ΔT>344 K, the solidification velocity decreases with the increase of undercooling. In this case, liquid/liquid phase separation takes place prior to solidification. The minor L₂ (Cu) droplets hinder the motion of the solidification front, and a monotectic transition may occur in the major L₁ phase. These facts caused by metastable phase separation are responsible for the slow growth at high undercoolings.     

Phase relations and optical properties of semiconducting ternary sulfides in the system Cu–Sn–S

The ternary system Cu–Sn–S was re-investigated and the phase diagram Cu₂S–SnS₂ studied in detail by differential thermal analysis and X-ray diffractometry. Three phases of composition Cu₄SnS₄, Cu₂SnS₃ and Cu₂Sn_3+xS_7+2x(0≤×≤1) were found exhibiting melting points at 833, 856 and 803 °C, respectively. Ellipsometric and diffuse reflectance measurements revealed that the latter two sulfides possess a fundamental band gap of 0.93 eV followed by a higher transitions. For the first time it could be demonstrated that Cu₂Sn₃S₇ has semiconducting properties and an absorption coefficients of the order 10⁵ cm⁻¹.     

Magnetism of the Tb2Fe14−xCoxB system

The Tb₂Fe_14−xCo_xB materials were synthesized for the entire composition range (x = 0–14) and studied by X-ray and magnetometry methods. All materials have a tetragonal crystal structure with decreasing lattice parameters upon Co substitution. The Curie temperature markedly rises for alloys with low Co content. Saturation magnetization at 77 K reaches a slight maximum around x ≈ 1 and gradually decreases for higher Co concentrations. An antiparallel coupling of 3d and Tb magnetic moments is inferred from saturation magnetization data. Anisotropy fields exhibit a maximum at low Co contents, but they decrease rapidly for x > 5. A spin reorientation (axis-to-plane) occurs at high temperature in materials with x ⩾ 12.5 due to competing effects of the terbium sublattice anisotropy and the 3d sublattice anisotropy. The spin-reorientation temperature becomes lower for alloys with higher Co content. The observed magnetic behavior is discussed in terms of preferential Co substitution into 16 k₂ sites and changes in the 3d sublattice due to Co introduction. A magnetic phase diagram is constructed for the Tb₂Fe_14-xCo_xB system and compared with that of Pr₂Fe_14-xCo_xB and Nd₂Fe_{14 -x}Co_xB systems.     

The most stable crystal structure and the formation processes of an order-disorder (OD) intermetallic phase in the Mg–Al–Gd ternary system

The most stable crystal structure for an 18R-type order-disorder (OD) intermetallic phase in the Mg–Al–Gd ternary system and its formation processes by annealing at 525?°C have been investigated by means of transmission electron microscopy and scanning transmission electron microscopy. The most energetically favourable polytype at 525?°C is found to be the structurally simplest one, a maximum degree of order polytype (monoclinic, 1M, space group: C2/m), described with a single stacking vector in stacking six-layer structural blocks. The formation of this simplest polytype occurs in the sequence of (i) enrichment of Gd and Al in four consecutive close-packed planes while keeping the hexagonal close-packed stacking of the AB-type, (ii) formation of Al₆Gd₈ clusters in the four consecutive atomic planes, introducing a stacking fault in the middle of the four consecutive atomic planes, (iii) thickening by the formation of Gd and Al-enriched four consecutive planes at a distance of two or three close-packed Mg atomic planes from the pre-existing Gd and Al-enriched four consecutive atomic planes so as to form six-layer and, sometimes seven-layer structural blocks, (iv) in-plane ordering of Al₆Gd₈ clusters in the four consecutive atomic planes and the stacking of structural blocks in the preferential stacking positions to form the OD structure, and (v) elimination of different structural blocks (other than six-layer ones) and the long-range ordering in the stacking of structural blocks.     

The interaction of O2 with the surface of polycrystalline gadolinium at the temperature range 300–670 K

Auger-Electron-Spectroscopy (AES) and Direct-Recoils-Spectrometry (DRS) were applied to study the interaction of O₂ with a polycrystalline gadolinium surface, in the temperature range 300–670 K and oxygen pressure up to 2 × 10^? 6 Torr. It has been found that initial uptake of oxygen, at coverage measurable by the techniques used here, results in rapid oxide island formation. The subsurface is believed to be a mixture of oxide particles and oxygen dissolved in the Gd metal, the latter being the mobile species, even at relatively low temperatures.Enhanced inward diffusion of oxygen starts as early as 420 K and dictates the surface oxygen concentration and effective thickness of the forming oxide. The oxygen accumulation rate at the near-surface region, as measured by the O(KLL) AES signal intensity, goes through a maximum as a function of temperature at 420 K. This is a result of the combination of still efficient oxygen chemisorption that increases surface occupation and slow inward diffusion. The thickest oxide, ~ 1.7 nm, is formed at 300 K and its effective thickness was found to decrease with increasing temperature (due to oxygen dissolution into the metal bulk).Diffusion coefficients of the oxygen dissolution into the bulk were evaluated for various temperatures utilizing models for infinitely thin oxide layer and thick oxide layer, respectively. The best fit under our experimental procedure was obtained by the thick layer model, and the coefficients that were calculated are D₀ = 2.2 × 10^? 16m²s^? 1 and E_a = 46kJ/mol.     

Analysis of the K S K S system from the reaction π − p → K S K S n at 40 GeV

On the basis of experimental data from the 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow), an amplitude analysis of 40 553 events of the reaction π ^? p → K _S K _S n induced by a negatively charged pion of energy 40 GeV is performed over a broad momentumtransfer range by using a new procedure. The results for |t| > 0.1 GeV² are obtained for the first time. In particular, resonances of mass 1700 and 1900 MeV and width 120 MeV are discovered in the D ₊ wave (there were no such resonances for |t| < 0.1 GeV²). In the region of low momentum transfers, the S wave exhibits a structure that lies in the mass region around 1370 MeV and which requires three resonances for its explanation. Two of these (that of mass 1234 ± 6 MeV and width 47 ± 33 MeV and that of mass 1478 ± 6 MeV and width 119 ± 10 MeV) were found in the studies of A. Etkin et al. [Phys. Rev. D 25, 2446 (1982)] and O.N. Baloshin et al. {Yad. Fiz. 43, 1487 (1986) [Phys. At. Nucl. 43, 959 (1986)]}. The third has a mass of 1389 ± 9 MeV and a width of 30 ± 24 MeV. At high momentum transfers, the S wave is found to feature resonances that have the following parameters: M = 1328 ± 8 MeV and Γ = 237 ± 20 MeV, M = 1440 ± 6 MeV and Γ = 121 ± 15 MeV, and M = 1776 ± 15 MeV and Γ = 250 ± 30 MeV. For the D ₀ wave, it is found that, in addition to the well-known resonances f ₂, a ₂, and f′ ₂, there appear the following resonances in this wave: a resonance of mass 2005 ± 12 MeV and width 209 ± 32 MeV and a resonance of mass 2270 ± 12 MeV and width 90 ± 29 MeV at low |t| and a resonance of mass 1659 ± 6 and width 152 ± 18 and a resonance of mass 2200 ± 13 MeV and width 91 ± 62 MeV at high |t|.     

Propagation Ultrasound Velocity at Plastic Deformation of Fe–Cr–Ni Alloy within 180–318 K

Russian Physics Journal - The paper studies the mechanical properties of the Fe–Ni–Cr alloy and the ultrasound propagation velocity (Rayleigh waves) during its plastic deformation...     

On colour non-singlet representations of the quark–gluon system at finite temperature

We use a group theoretical technique to project out the partition function for a system of quarks, antiquarks and gluons onto a particular representation of the internal symmetry group SU(3): the colour singlet, colour octet and colour 27-plet, at finite temperature. We do this to calculate the thermodynamic quantities for those representations. We also calculate the change in free energy of the plasma droplet formed from the hot hadronic gas. We find that the size of the droplet in the colour-octet representation is smaller than that in the colour-singlet representations at different temperatures in the vicinity of the critical temperatures of the phase transitions. Received: 1 February 1999 / Revised version: 24 February 2000 / Published online: 18 May 2000     

Orientation magnetic phase transition induced by shock loading of the Fe–Cr–Co alloy

The strength characteristics of Fe–Cr–Co alloys have been investigated under high-strain-rate deformation of samples. It has been found that, under shock-wave loading, a significant remanent magnetization appears in the samples and their fragments due to the orientation magnetic phase transition. The threshold pressures of the magnetic phase transition have been determined, and the distribution of the remanent magnetization in the samples has been analyzed.     

Plastic deformation of a monoclinic Al13Fe4 at 300 ∼ 873 K

The plasticity of monoclinic Al₁₃Fe₄ particles grown in a spray-formed Al–Fe alloy is examined after being submitted to two deformation modes between 300 and 873 K by specially designed semi-in situ compression tests; one is uniform and the other is by indentation. In the uniform mode, cracks propagate through the Al₁₃Fe₄ particles along the pentagonal column planes, leaving extremely thin and heavily deformed plastic zones along the cracked faces at 300 and 473 K. In contrast, the generation of isolated dislocations and their motion govern the plastic deformation at 673 and 873 K. In the indentation mode, local deformation is achieved exclusively by individual dislocations over the whole range of temperature explored. A possible mechanism of dislocation motion in monoclinic Al₁₃Fe₄ is discussed based on Burgers vector analyses coupled with the three-dimensional observation of dislocation configurations.