Calculation of the thermodynamic interaction parameter ρ C C,Ni , in the austenite of the Fe-C-Ni system

In the study, the interaction model has been considered, which assumes that the radius of interaction between carbon and nickel atoms in austenite corresponds to the nearest neighborhood of an octahedral interstice by lattice sites, and the interaction radius between two carbon atoms corresponds to two nearest coordination shells formed by octahedral interstices in the lattice. The three-particle potential of approach of C-Ni-C atoms is taken equal to zero. The pair potential of interaction between carbon atoms in austenite is taken to be equal to that obtained from the data of Mössbauer spectroscopy. In this model, the magnitude of the secondorder thermodynamic cross-interaction parameter ρ _C ^{C, Ni} in the austenite at a temperature of 1273 K has been calculated. The results of the calculation (ρ _C ^{C, Ni} = 11.4) satisfactorily agree with the experimental value (ρ _C ^{C, Ni} = 11.1).     

Surface properties of Langmuir films of mono-, di-, and tetra-n-octyl adducts of C60 at the water–air interface

Relatively stable Langmuir films of mono-, di-, and tetra-n-octyl adducts of C₆₀ were prepared at the water–air interface. The adducts were obtained by selective bulk electrosynthesis at controlled potential. For the films, surface pressure (π) and a surface potential change (ΔV) were simultaneously measured as a function of surface area per molecule (A) during the film compression. The spreading properties of the adducts strongly depend on the number of n-octyl chains linked to the C₆₀ cage and nature of the spread solution. The determined zero-pressure limiting area per molecule (A₀) is larger the more n-octyl chains are attached to the C₆₀ cage. Aggregated multilayer films are formed for the toluene and tetrahydrofuran spread solutions while liquid monolayer films for the chloroform solutions. Remarkably, relatively stable liquid monolayer films of pristine C₆₀ are obtained also from the chloroform solutions. For relatively concentrated chloroform solutions, plateaus are developed in the π–A adduct isotherms. Isotherms for both concentrated and diluted chloroform solutions show reversible compression and expansion with virtually no hysteresis. Comparison of the estimated and determined A₀ values indicates that all adduct molecules are horizontally oriented in the monolayer films. Unexpectedly, large mean dipole moment components normal to the water–air interface, determined from inflection points of the ΔV–A isotherms, are presumably due to preferential orientation of water molecules adjacent to the interface of the water subphase and the floating adduct film.     

Experimental Determination of the Phase Equilibria of the La-Zn-Si System at 600 °C

The isothermal section at 600 °C of the La-Zn-Si system was established by using equilibrated alloys and the diffusion couple technique. Microstructural observation and phase identification were performed using optical microscopy, scanning electron microscopy with energy dispersive x-ray spectroscopy and a wave dispersive x-ray spectrometer, and x-ray powder diffraction. Seven ternary compounds were identified in this ternary system, and temporally designated as τ ₁, τ ₂, τ ₃, τ ₄, τ ₅, τ ₆ and τ ₇. Two previously reported ternary compounds, viz. τ ₁ and τ ₂, were found to exist at 600 °C. EDS analysis revealed that the τ ₁ phase contained Si from 2.4 to 6.1 at.% and La from 22.3 to 23.3 at.%. The compositional region of the τ ₂ single-phase ranged from 28.3 to 40.7 at.% for Si and from 31.5 to 33.1 at.% for La. Two new ternary phases, τ ₅ and τ ₆, were identified. The τ ₅ phase with the CeNiSi₂-type was determined to have a composition range of 36.9-39.2 at.% Si for about 24 at.% La. The τ ₆ phase with the ThCr₂Si₂-type was found to have a composition range of 18.9-19.7 at.% La and 27.4-30.6 at.% Si. The crystal structures of τ ₃, τ ₄, and τ ₇ were not determined. The solubility of Si in LaZn₁₃, LaZn₁₁, La₂Zn₁₇, La₃Zn₂₂, and LaZn₅ was negligible, and that of Si in LaZn₄, LaZn₂ and Zn in LaSi₂, La₃Si₂ was determined as 5.1, 2.3, 16.2 and 3.8 at.%, respectively.     

Efferct of the μ-phase on the properties of superhigh-temperature derofmable nickel alloy KhN60KVYuMB

One of the requirements imposed on high-temperature nickel alloys for long-term operation under high temperatures and stresses is structural stability, which ensures constant properties during operation of parts. It is known that the main strengthening phase of nickel alloys is a -phase of the type (Ni, Cr)₃(Al, N) or (Ni, Cr)₃(Al, Ti, Nb), which may amount to 50% in deformable nickel alloys. In addition, these alloys contain a certain amount of carbides, borides, and carbonitrides (up to 3 wt. %). An increase in the content of alloying elements in high-temperature alloys may cause formation of undesirable TCP-phases in their structure. For example, at high contents of molybdenum and tungsten a thin lamellar p-phase (Ni, Co, Fe)₇(Mo, W)₆ is segregated. The authors investigated the effect of the -phase on the set of chemical properties of industrial alloy KhN60KVYuMB (pressed rods 105 mm in diameter).Translated from Metailovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 15–19, September, 1995.     

The Zn-Rich Corner of the 450 °C Isothermal Section of the Zn-Fe-Ni-Sb Quaternary System

The 450 °C isothermal section of the Zn-Fe-Ni-Sb quaternary system with Zn fixed at 93 at.% has been studied experimentally using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray diffraction. The (L + T-FeNiZn) field is found to be coexistent with all other phase fields in the section, except the (ζ-FeZn + Sb₂Zn₃) field. The Sb solubility in the ζ-FeZn phase is very limited, and it almost insoluble in the δ-NiZn phase. The solubilities of Fe and Ni in the Sb₂Zn₃ phase are 0.6 and 0.9 at.%, respectively. The maximum solubility of Sb in the γ-NiZn phase is 1.9 at.%. Three four-phase regions and two three-phase regions have been confirmed experimentally in this isothermal section. In addition, no new phase was found in the study.     

Experimental Investigation of the Isothermal Section at 800 °C of the Nd-Fe-Co Ternary System

The phase equilibrium of the ternary Nd-Fe-Co system at 800 °C was investigated by means of powder x-ray diffraction and scanning electron microscopy–energy dispersive x-ray spectroscopy. Seven binary compounds, i.e., Nd₂Co₁₇, NdCo₅, Nd₅Co₁₉, Nd₂Co₇, NdCo₃, NdCo₂, Nd₂Fe₁₇ were identified to exist at this isothermal section. This isothermal section consists of ten single-phase, ten two-phase and six three-phase regions. All measured compositions and unit-cell refinements were performed at room temperature from quenched samples annealed at 800 °C for one week. The maximum solubility at 800 °C of Fe in NdCo_2?x Fe _x (MgCu₂-type structure, Fd-3 m), NdCo_3?x Fe _x (PuNi₃-type structure, R-3 m space group), Nd₂Co_7?x Fe _x (Ce₂Ni₇-type structure, R-3 m), Nd₅Co_19?x Fe _x (CeCo₁₉-type structure, R-3 m space group), NdCo_5?x Fe _x (CaCu₅-type structure, P6/mmm), Nd₂Co_17?x Fe _x (Th₂Zn₁₇ type structure, R-3 m) and Nd₂Fe_17?x Co _x (Th₂Zn₁₇ type structure, R-3 m) are about 31.6 at.% Fe, 47.9 at.% Fe, 13.3 at.% Fe, 8.6 at.% Fe, 10.37 at.%, 36.35 at.% Fe, and 58.23 at.% Fe respectively. The solid solubility range of Co in Nd₂Fe₁₇ form discontinuous series of 2 ranges is about 0-30.14 at.% Co, and 51.9-100 at.% Co and the solid solubility range of Fe in Nd₂Co₁₇ is about 0-48.1 at.% Fe, and 69.86-100 at.% Fe.     

Experimental Investigation of the 650 °C Isothermal Section of the Cu-Fe-Si Ternary Phase Diagram

The isothermal section of the Cu-Fe-Si ternary system at 650 °C was investigated by scanning electron microcopy, coupled with energy dispersive x-ray spectroscopy and x-ray diffraction. Seven three-phase regions exist in the isothermal section of the Cu-Fe-Si ternary system. No new ternary compound was found in this section. The solubility of Fe in η(Cu₃Si), ε(Cu₁₅Si₄), γ(Cu₅Si) and κ(Cu_6.69Si) phases was low. The solubility of Fe in (Cu) was found to decrease when Si content was increased in the range from 5.3 at.% to 11.9 at.%. The maximum solubilities of Cu in FeSi, FeSi₂ and (αFe) were 1.7 at.%, 3.3 at.% and 1.6 at.%, respectively, and the maximum solubilities of Si in (Cu) and (αFe) were 11.9 at.% and 27.1 at.%, respectively.     

Celebrating the 60th Anniversary of Publication of FOUNDRY Journal 1952-2012

The monthly journal FOUNDRY, formerly known as FOUNDRY-MEN, was the first journal on foundry technology in China and publication started in 1952. In 1970, the journal was moved to Shenyang and edited for publication by the Shenyang Research Institute of Foundry (SRIF). In 1983, the journal was formally named FOUNDRY, edited and published by the SRIF     

An Experimental Study of the Liquid Domain of the Zn-Fe-Al-Mn Quaternary System at 460 °C

The liquid domain of the Zn-Fe-Al-Mn quaternary system at 460 °C was experimentally investigated. The nature of relevant intermetallic compounds was studied using scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS). A total of 12 Fe-oversaturated baths with various Mn additions was prepared for the study. When the Al addition was fixed at 0.14 wt.%, δ-FeZn₁₀ and δ-MnZn₉ were found to co-exist with the liquid phase at low Mn additions. Increasing Mn additions above 1.3 wt.% greatly stabilized δ-MnZn₉ so that it became the sole compound existing in the liquid phase. When the Al addition was fixed at either 0.16 or 0.27 wt.%, η-Fe₂Al₅ was found at low Mn additions but ceased to exist as Mn additions increased above 0.8 wt.%. The current study indicates that the addition of Mn to the bath promotes the formation of δ phases, thus shifting the invariant point of δ/η in the Zn-Fe-Al ternary system to a higher Al level. Based on experimental results, the liquidus surfaces in the Zn-rich corner of the quaternary system at 460 °C were schematically constructed, and implications for practical galvanizing operations were suggested.     

Investigation of the Fluorine Microalloying Effect in the Oxidation of TiAl at 900°C in Air

High-temperature oxidation resistance of gamma titanium aluminides can be achieved by the formation of a continuous scale of slowly growing Al₂O₃. The formation of such a scale was favored by the addition of small amounts of fluorine. It is shown that fluorine can have a beneficial effect on oxidation resistance in a certain F-range which is quantified by thermodynamic calculations and by experimental investigations. It is assumed that the F-effect offers a significant potential for improvement of the oxidation resistance of technological TiAl alloys.     

The 450 °C Isothermal Section of the Zn-Fe-Ti System

The 450 °C isothermal section of the Zn-Fe-Ti ternary system with an emphasis on the Zn-rich corner was experimentally determined by means of optical microscopy, scanning electron microscopic/energy-dispersive spectrometric (SEM-EDS) analysis, and x-ray diffraction. A true ternary phase T with an approximate formula of TiFe₂Zn₂₂ has been identified. This phase is in equilibrium with all phases in the system, except and Ti₂Zn. Four Ti-Zn binary compounds, TiZn₁₆, TiZn₈, TiZn₃, and TiZn, were found in this study.     

Isothermal Section of the Al-Mn-Dy System at 500 °C

Phase relationships in the Al-Mn-Dy ternary system at 500 °C have been investigated by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, and electron probe microanalysis. From the experimental results it was concluded that the isothermal section consists of 16 single-phase regions, 26 two-phase regions and 12 three-phase regions. Two extensive solid solutions, (Al _x Mn_1?x )₁₂Dy and (Al_1?x Mn _x )₂Dy, were observed. The solid solution (Al _x Mn_1?x )₁₂Dy forms by Al replacing Mn in Mn₁₂Dy, while the continuous solid solution (Al_1?x Mn _x )₂Dy forms by Mn and Al mutually substituting in Al₂Dy and Mn₂Dy, respectively. The maximum solid solubility of Al in Mn₁₂Dy is 79.3 at.%.     

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.     

Plasma and Gaseous Nitrocarburizing of C60W Steel for Tribological Applications

A comparison has been made between plasma and gas nitrocarburizing processes for C60W steel in terms of structural features of the layers and the tribological properties of the specimens. Gaseous treatments were performed in a sealed quench industrial furnace in optimized process cycles. For plasma nitrocarburizing, a semi - industrial size unit was operated at a range of process parameters. Experimental results indicate that increasing the treatment time increases the thickness of the compound layer but lowers the wear resistance. Plasma treatment produced a more effective case depth compared with gaseous process, providing a better uniformity. Analysis of X-ray diffraction patterns indicated that the compound layer in gas nitrocarburizing consisted of both e and γ‘ phases, whereas in plasma nitrocarburizing the ε phase was not detected.     

450 °C Isothermal Section of the Zn-Fe-Cu Ternary System

The 450 °C isothermal section of the Zn-Fe-Cu ternary system was experimentally determined by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectrometer (EDS)/Wave Dispersive X-ray Spectrometer (WDS), and X-ray Diffractometer (XRD). Eight three-phase regions exist in the 450 °C isothermal section of the Zn-Fe-Cu ternary system. No new ternary compound was found in the system. The δ_Fe phase (FeZn₁₀) can be in equilibrium with all phases except the α-Fe, (Cu) and β′ (CuZn) phase. Experimental results indicated that the solubility of Cu in the Γ (Fe₃Zn₁₀) and the δ_Fe phase reaches as high as 17.9 and 15.2 at.%, respectively.     

Phase equilibria in the Mg-rich corner of the Mg-Zn-La system at 350°C

1. Introduction Mg-based alloys are attractive for applications because of the light weight and a high specific strength. Among the common alloying elements, the addition of zinc could make the magnesium alloys strengthen by precipitation [1-2]. The further addi- tion of the rare-earth elements to the Mg-Zn alloys is more effective on the precipitation-strengthening [3-4]. But phase diagrams of the Mg-Zn-RE system, as the basis of the alloying, have hardly been built up [5-6]. The phase equ…     

450 °C Isothermal Section of the Ni-Sb-Zn Ternary System at the Zn-Rich Corner

The 450 °C isothermal section of the Ni-Sb-Zn ternary system with an emphasis on the Zn-rich corner was experimentally determined by means of optical microscopy, SEM-EDS analysis and x-ray diffraction. The existence of two true ternary phase, the NiSbZn (τ₁) and Ni₂SbZn₂ (τ₂) phase, was confirmed in the system at 450 °C. NiSbZn (τ₁) had an MgAgAs-type structure with a lattice parameter a = 0.58971 nm. Ni₂SbZn₂ (τ₂) is a ternary compound found in this system for the first time whose composition range spanned from 35.5-38.0 at.% Ni, 17.3-26.3 at.% Sb, 36.9-45.2 at.% Zn. It should be noted that the phase relationships at 450 °C are significantly different from the previous reported ones at 600 and 297 °C. The solubilities of Ni in SbZn, Sb₃Zn₄ and Sb₂Zn₃ were limited. The maximum solubilities of Sb in δ-NiZn₈, γ-NiZn₃ and β₁-NiZn were 0.1, 4.0 and 1.5 at.%, respectively and the maximum solubilities of Zn in NiSb and NiSb₂ were 5.6 and 1.6 at.%, respectively.     

Effect of the magnetic state of ferrite on transformations in Fe−C alloys

Conclusions Retardation of the austenite transformation in the interval end of the pearlite—austenite transformation to start of the ferrite—austenite transformation in low-carbon steels, which coincides with the magnetic transformation in ferrite, is connected with the fact that the latter inhibits diffusional transport of the interstitial atoms.Alma-Ata Institute of Railroad Transportation Engineers. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 11–12, February, 1990.