Quasi-Ternary System Ag2Se-CdSe-Ga2Se3

Phase equilibria in the quasi-ternary system Ag₂Se-CdSe-Ga₂Se₃ were investigated by differential thermal and x-ray phase analysis methods. Phase diagrams of nine vertical sections were constructed. The boundaries of seven single-phase fields were determined which are solid solution ranges of system components and intermediate phases. We constructed the isothermal section at 820 K and the liquidus surface projection, and have determined the position in the system of six invariant processes with the participation of liquid: $ {\text{L}}_{{{\text{U}}_{1} }} + {\upzeta} {\leftrightarrows} {\upbeta} + {\upeta} $ L U 1 + ζ ? β + η (1145 K), $ {\text{L}}_{{{\text{U}}_{ 2} }} + \upzeta \leftrightarrows \upgamma + \upeta $ L U 2 + ζ ? γ + η (1138 K), $ \text{L}_{{U_{3} }} + \upeta \leftrightarrows \updelta + \upgamma $ L U 3 + η ? δ + γ (1113 K), $ {\text{L}}_{{{\text{E}}_{ 1} }} \leftrightarrows \upbeta + \updelta + \upeta $ L E 1 ? β + δ + η (1083 K), $ {\text{L}}_{{{\text{E}}_{ 2} }} \leftrightarrows \upalpha + \upbeta + \upvarepsilon $ L E 2 ? α + β + ε (969 K), $ {\text{L}}_{{{\text{E}}_{ 3} }} \leftrightarrows \upbeta + {\updelta} + \upvarepsilon $ L E 3 ? β + δ + ε (963 K). Two invariant processes in the sub-solidus part, $ \upbeta + \updelta \leftrightarrows \upeta + \uplambda $ β + δ ? η + λ and $ \upbeta + \updelta \leftrightarrows \upvarepsilon + \uplambda $ β + δ ? ε + λ at 968 and 938 K, respectively, were investigated as well.     

Relationship of Ca, B, and AlP in Al–12.6Si alloy

P modification has been widely used in Al-Si piston industry, but trace of Ca element has great influence on the P modification efficiency. In this work, it is found that primary Si can be heterogeneously nucleated by AlP in near eutectic Al-12.6Si alloy, but Ca element may destroy the P modification efficiency, whereas the addition of B can recover the P modification efficiency in near eutectic Al-12.6Si alloy with high Ca containing. The microstructure transformation was related to the reaction of Ca, B, and AlP. According to the thermodynamic calculation, Ca may react with AlP and form Ca3P2 compound in Al-Si alloy, whereas, when B was added into the melt, AlP could be reformed. The reaction of Ca, B, and AlP can be shown as follows: 2AlP +3Ca→Ca3P2+2Al; Ca3P2+18B+2Al→3CaB6+2AlP. In addition, with B added into the Al-12.6Si alloy with Ca and P addition, the mechanical properties were improved compared with single Ca and/or P addition.     

Effect of H2S on High Temperature Corrosion of Fe–Ni–Cr Alloys in Carburizing/Oxidizing Environments

This investigation involves the corrosion behavior of two Fe–Ni–Cr alloys containing different Si content at 1050?°C in carburizing-oxidizing environments (typical of ethylene pyrolysis) with varied concentration of H₂S. High-Si containing alloy could form thinner but less uniform oxide scale than low-Si alloy after pre-oxidation due to the barrier effect of continuous SiO₂ at interface of scale/substrate. Pre-oxidized alloy showed a better resistance to carburization/sulfidation attacks than the bare alloy in absence of pre-oxidation. It was found that carburization and sulfidation of the Fe–Ni–Cr alloys could be prevented in the environment with a ratio of $ P_{{{\text{H}}_{ 2} {\text{S}}}} /P_{{{\text{H}}_{ 2} }} $ at 1.7?×?10^?5. When the sulfur partial pressure was lower than this value, oxides were found to be converted to porous and non-protective carbides. When the sulfur potentials were increased, manganese or chromium sulfide on outer layer and internal sulfide stringers mixed with silicon oxide in substrate could be formed. Under high sulfur partial pressures, spallation of outer sulfide or oxide scale was observed on high-Si alloy due to less stability of oxide layer formed at surface which was converted to sulfide faster than on low-Si alloy.     

Phase Identification of Cu-In Alloys with 45 and 41.25 at.% In Compositions

In this work, the thermal stability of Cu-In alloys with 45.0 and 41.2 at.% In nominal compositions was investigated by differential scanning calorimetry (DSC), scanning electron microscopy, wavelength dispersive spectroscopy, and in-situ synchrotron x-ray powder diffraction (S-PXRD) over a temperature range from 25 up to 400 °C. The studied samples are mainly composed of a Cu₁₁In₉ phase together with minor amounts of the B phase (based on the NiAs-Ni₂In type structure) and, in one of the samples, with a minor amount of pure In. No evidence of the Cu₁₀In₇ (41.2 at.% In) phase was detected, not even in the sample with 41.2 at.% In nominal overall composition. The combined use of the S-PXRD and DSC techniques allowed us to identify two phase transitions involving the Cu₁₁In₉ phase, one of them corresponding to the $ \upeta^{\prime} \rightleftharpoons {\text{B}} + {\text{Cu}}_{11} {\text{In}}_{9} $ reaction at T = 290 °C and the other to the peritectic $ \upeta^{\prime} + {\text{L}} \rightleftharpoons {\text{Cu}}_{11} {\text{In}}_{9} $ reaction at T = 311 °C.     

\left\{ {10\bar 12} \right\} twinning behavior in magnesium single crystal

In order to investigate $\left\{ {10\bar 12} \right\}$ tensile twinning behavior, the magnesium single crystal was deformed by compressing along the $\left[ {2\bar 1 \bar 10} \right]$ direction at room temperature, as $\left\{ {10\bar 12} \right\}$ tensile twinning easily takes place when the compression direction is perpendicular to the c-axis. Numerous $\left\{ {10\bar 12} \right\}$ primary tensile twins were activated during deformation, and the Schmid factor (SF) criterion was applied to the six $\left\{ {10\bar 12} \right\}$ twin variants. The analysis shows that the majority of the $\left\{ {10\bar 12} \right\}$ primary twins belong to high SF variants, and high SF twin boundaries provided nucleation sites for low SF variants. The $\left\{ {10\bar 12} \right\}$ secondary tensile twins were formed inside the high SF of wide $\left\{ {10\bar 12} \right\}$ primary twin bands, and the basal plane of the $\left\{ {10\bar 12} \right\}$ secondary twin was tilted about 60° with respect to the original parent matrix. In the case of the $\left\{ {10\bar 12} \right\}$ secondary tensile twin, relatively low SF variants were activated while counterparts with higher SF variants were absent.     

Pressure dependencies of copper oxidation for low- and high-temperature parabolic laws

Studies of the oxidation kinetics of copper have been conducted in the thin-film range at temperatures of 383–398 K and in the oxygen pressure range of 0.278–21.27 kPa; whereas in the thick-film regime at 1123 K, studies have been conducted in the oxygen pressure range of 2.53–21.27 kPa. Furthermore, the effect of continuously impressed direct current with oxygen pressure variation in Wagner's parabolic range has been studied also in order to have a better understanding of the effective charge on the migrating species. In the low-temperature range, the rate constant, k_P ∝ \(P_{O_2 }^{1/4} \) , suggesting that the migration of neutral vacancies in the growing film predominates. At high temperature, 1123 K, in the Wagnerian regime, the observed approximate pressure dependencies of the parabolic rate constants are the following: $$\begin{gathered} {\text{k}}_{\text{p}} (normal oxidation) \propto \sim {\text{P}}_{{\text{O}}_{\text{2}} }^{{\text{1/7}}} \hfill \\ {\text{k}}_{\text{p}} (sample cathodic) \propto \sim {\text{P}}_{{\text{O}}_{\text{2}} }^{{\text{1/5}}} \hfill \\ \end{gathered} $$ and $${\text{k}}_{\text{p}} (sample anodic) \propto \sim {\text{P}}_{{\text{O}}_{\text{2}} }^{{\text{1/10}}} $$ .     

Water Vapour Effects on FeO Scale Growth: Differences Between Iron and Steel

High purity iron and a low carbon, low silicon steel were oxidised at temperatures of 800–1,200 °C, in atmospheres of N₂–H₂–H₂O and N₂–O₂–H₂O. Scales of wüstite grew at low oxygen potentials, and of FeO/Fe₃O₄/Fe₂O₃ at high oxygen potentials, both according to parabolic kinetics after an initial transient period. The iron and steel behaved similarly in the O₂/H₂O gases, but not in H₂/H₂O, where the steel oxidised much more slowly than the iron. The rate for steel increased with $ p_{{H_{2} O}} $ at fixed $ p_{{O_{2} }} , $ but for iron was almost independent of $ p_{{H_{2} O}} , $ whilst rates for both metals increased with $ p_{{O_{2} }} $ at fixed $ p_{{H_{2} O}} $ . These results are discussed using point defect models involving hydroxyl anions and cation vacancies. Scaling rates in O₂/H₂O also increased with $ p_{{H_{2} O}} , $ a result attributed to gas phase transport within oxide pores which were present in the scales, but absent in wüstite grown in H₂/H₂O.     

Transformations of Carbides During Tempering of D3 Tool Steel

The studies were performed on D3 tool steel hardened after austenitizing at 1050 °C during 30 min and tempering at 200-700 °C. Based on the diffraction studies performed from the extraction replicas, using electron microscopy, it was found that after 120-min tempering in the consecutive temperatures, the following types of carbides occur: $$ 200\;^\circ {\text{C}} \to \upvarepsilon + \upchi + {\text{ Fe}}_{ 3} {\text{C}},\quad 3 50\;^\circ {\text{C}} \to \upvarepsilon + \upchi + {\text{ Fe}}_{ 3} {\text{C,}} $$ $$ 500\;^\circ {\text{C}} \to \upchi + {\text{ M}}_{ 3} {\text{C }} + {\text{ M}}_{ 7} {\text{C}}_{ 3} ,\quad 600\;^\circ {\text{C}} \to \upchi + {\text{ M}}_{ 3} {\text{C }} + {\text{ M}}_{ 7} {\text{C}}_{ 3} , $$ $$ 700\;^\circ {\text{C}} \to {\text{M}}_{ 3} {\text{C }} + {\text{ M}}_{ 7} {\text{C}}_{ 3} . $$ Apart from higher mentioned carbides, there are also big primary carbides and fine secondary M₇C₃ carbides occurring, which did not dissolve during austenitizing.     

Sulfidation properties of an Fe-26.4Cr-8Al-6Mn alloy at 973 and 1073 K in H2S-H2 atmospheres,10^{ - 4} \leqslant {\text{P}}_{{\text{S}}_{\text{2}} } \leqslant 10^2 {\text{Pa}}

The sulfidation behavior of an Fe-26.4Cr-8Al-6Mn (at.%) alloy in H₂S-H₂ atmospheres, \(10^{ - 4} \leqslant {\text{P}}_{{\text{S}}_{\text{2}} } \leqslant 10^2 {\text{Pa}}\) .     

Modeling the Correlation of Composition-Processing-Property for TC11 Titanium Alloy Based on Principal Component Analysis and Artificial Neural Network

In the present investigation, the correlation of composition-processing-property for TC11 titanium alloy was established using principal component analysis (PCA) and artificial neural network (ANN) based on the experimental datasets obtained from the forging experiments. During the PCA step, the feature vector is extracted by calculating the eigenvalue of correlation coefficient matrix for training dataset, and the dimension of input variables is reduced from 11 to 6 features. Thus, PCA offers an efficient method to characterize the data with a high degree of dimensionality reduction. During the ANN step, the principal components were chosen as the input parameters and the mechanical properties as the output parameters, including the ultimate tensile strength ( $ \upsigma_{\text{b}} $ ), yield strength ( $ \upsigma_{0.2} $ ), elongation ( $ \updelta $ ), and reduction of area (??). The training of ANN model was conducted using back-propagation learning algorithm. The results clearly present ideal agreement between the predicted value of PCA-ANN model and experimental value, indicating that the established model is a powerful tool to construct the correlation of composition-processing-property for TC11 titanium alloy. More importantly, the integrated method of PCA and ANN is also able to be utilized as the mechanical property prediction for the other alloys.     

On the Liquid/Solid Phase Equilibria in the Al-Rich Corner of the Al-Si-Ti Ternary System

The nature of liquid-solid phase equilibria in the Al-rich corner of the Al-Si-Ti system are determined by drawing three isothermal sections at 620, 680 and 727 °C. The solubility of Ti in Al-Si liquids is determined for four different compositions (0, 9, 13 and 18 at.%Si) at temperature below 800 °C. Combination of the two sets of experimental results leads to an attempt of liquidus projection. The primary crystallization surface of Al₃Ti is found to extend up to 9.5 at.%Si in the liquid phase at 620 °C and 11 at.%Si at 727 °C. The solubility of Ti is found to be not significantly dependent on the Si content of the liquid. From DSC measurements and deduction on microstructure, the last invariant reaction of the solidification path is found to be quasi-peritectic: ${\text{L}} + \uptau_{1} - {\text{Ti}}_{7} {\text{Al}}_{5} {\text{Si}}_{12} \Leftrightarrow {\text{Al}} + {\text{Si}} .$      

Electrochemical and Sulfide Stress Corrosion Cracking Behaviors of Tubing Steels in a H2S/CO2 Annular Environment

The electrochemical and sulfide stress corrosion cracking (SSCC) behaviors of 13Cr stainless steel and P110 steel were investigated in a simulated acidic annular environment with low-temperature and high-pressure H₂S/CO₂ using electrochemical methods, U-bend immersion tests, and scanning electron microscopy. In the solution containing high pressure CO₂, 13Cr, and P110 steels exhibited general corrosion and severe pitting, respectively. Compared with sweet corrosion, additional H₂S in the solution enhanced the corrosion of 13Cr steel but inhibited the corrosion of P110 steel. By contrast, in a solution containing 4 MPa CO₂ and different $ {P}_{{{\text{H}}_{ 2} {\text{S}}}}$ (0-0.3 MPa), the susceptibility of both 13Cr stainless steel and P110 steel toward SSCC was significantly promoted by increases in H₂S partial pressure. The 13Cr stainless steel exhibited higher susceptibility toward SSCC than P110 steel under a H₂S/CO₂ environment but lower susceptibility under a pure CO₂ environment.     

Texture Evolution in a Ti-Ta-Nb Alloy Processed by Severe Plastic Deformation

Titanium alloys are extensively used in a variety of applications because of their good mechanical properties, high biocompatibility, and corrosion resistance. Recently, ??-type Ti alloys containing Ta and Nb have received much attention because they feature not only high specific strength but also biocorrosion resistance, no allergic problems, and biocompatibility. A Ti-25Ta-25Nb ??-type titanium alloy was subjected to severe plastic deformation (SPD) processing by accumulative roll bonding and investigated with the aim to observe the texture developed during SPD processing. Texture data expressed by pole figures, inverse pole figures, and orientation distribution functions for the (110), (200), and (211) ??-Ti peaks were obtained by XRD investigations. The results showed that it is possible to obtain high-intensity share texture modes ({001}??110??) and well-developed ?? and ??-fibers; the most important fiber is the ??-fiber ({001} $ \left\langle {1\bar{1}0} \right\rangle $ to {114} $ \left\langle {1\bar{1}0} \right\rangle $ to {112} $ \left\langle {1\bar{1}0} \right\rangle $ ). High-intensity texture along certain crystallographic directions represents a way to obtain materials with high anisotropic properties.     

Comparative TEM investigation on the precipitation behaviors in Cu–15wt%Sn alloy

The decomposition and precipitation behaviors of a quenched Cu–15wt%Sn alloy as a function of aging temperature were investigated using transmission electron microscopy (TEM). Focused ion beam (FIB) was employed to assist TEM specimen preparation. At 300 °C, the decomposition of the supersaturated α′ phase occurred at grain boundaries, displaying a cellular morphology. The lamellae were found with ζ and α phases, rather than with the equilibrium ε and α phases. The ζ and α phases exhibit a well-defined orientation relationship (OR) as $ (1\bar{1}0)_{\alpha } //(0001)_{\zeta } ,\;[11\bar{2}]_{\alpha } //[\bar{1}2\bar{1}0]_{\zeta } $ . On the other hand, at 320 °C, only incipient lamellar structures of several micron meters were observed, which were composed of the δ and α phases. At the same time, abundant intragranular precipitation of the ε phase in the form of platelets was observed, and OR as $ (1\bar{1}1)_{\alpha } //(001)_{\varepsilon } , $ [110] _α //[100] _ε exists between ε phase and the α phase. These contrasting precipitation behaviors are discussed from the viewpoint of crystallographic coherency of these phases.     

Transient Oxidation of Cu-5at.%Ni(001): Temperature Dependent Sequential Oxide Formation

The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytical high-resolution TEM. We observed the formations of nanosized NiO and Cu₂O islands when Cu-5at.%Ni(001) was exposed to oxygen partial pressure, $ {\text{pO}}_{ 2} = 1 \times 10^{ - 4} \,{\text{Torr}} $ and various temperatures in situ. At 350 °C epitaxial Cu₂O islands formed initially and then NiO islands appeared on the surface of the Cu₂O island, whereas at 550 °C NiO appeared first. XPS and TEM revealed a sequential formation of NiO and then Cu₂O islands at 550 °C. The temperature-dependent oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.     

The Effect of Texture on the Corrosion Behavior of AZ31?Mg Alloy

Magnesium (Mg) grains show anisotropic corrosion behavior, which implies that the single-phase, hot-rolled Mg alloy AZ31 sheet, if highly textured, will have different corrosion performance depending on its crystallographic orientation of the grains. Its rolling surface, dominated by (0001) basal crystallographic planes, is more corrosion resistant than its cross-section surface, which is mainly composed of $ \{ 10\overline{1} 0\} $ and $ \{ 11\overline{2} 0\} $ prismatic crystallographic planes. Furthermore, grain refinement by hot rolling is beneficial to the overall corrosion resistance of AZ31 because of the dissolution of AlMn(Fe) intermetallic precipitates in the alloy. Surface compressive deformation machining can lead to refined grains and an expected preferred grain orientation, thus improving the corrosion resistance of AZ31 alloy.     

Characterization of crystallographic properties of GaN thin film using automated crystal orientation mapping with TEM

The GaN thin film deposited on an amorphous glass substrate was analyzed by using transmission electron microscopy with a new automated crystal orientation mapping tool. Film deposition was made at 600°C for 4 h by the hyperthermal neutral beam (HNB) source. Columnar crystals oriented to the [0001] direction without significant disordering were clearly observed. Electron diffraction patterns indicated that the crystals have mainly two different zone axes, [2 $\bar 1$ $\bar 1$ 0] and [10 $\bar 1$ 0]. This crystallographic and microstructural information provides the guidance for future works for the HNB source to obtain GaN thin films of higher quality on amorphous substrates.     

Glass Reinforcement of Various Epoxy Resins-Polyurea Systems

Polyureas (PUs) were prepared by the polycondensation reaction of disperse dyes containing -NH₂ group and toluene 2, 4-diisocyanate. The disperse dyes have been prepared by coupling of various 2-diazobenzothiazoles with 1,3-benzenediamine. All the PUs were characterized by elemental analysis, spectral studies, number average molecular weight $ \left( {\overline{\text{Mn}} } \right), $ and thermogravimetry. Further reaction of PUs was carried out with an epoxy resin (i.e., DGEBA). The curing study of prepared resins was monitored by differential scanning calorimeter (DSC). Based on DSC, thermograms glass fiber-reinforced composites have been laminated and characterized by chemical, mechanical, and electrical properties. The unreinforced cured resins were subjected to thermogravimetric analysis (TGA). The laminated composites showed excellent resistance properties against chemicals and good mechanical and electrical properties.     

Secondary recrystallization in Fe-3% Si alloy with (110)[001] single-component texture

After the primary recrystallization of a preliminarily deformed (110)[001] single crystal, the texture also has the preferred (110)[001] orientation. Furthermore, the texture contains weak orientations, a major part of which is formed at the sample surface and can be described by a spectrum of scattered orientations {120}〈210〉…{351}〈103〉. A further heating leads to two concurrent processes taking place in the samples, i.e., the normal growth of Goss grains and secondary recrystallization. Abnormally grown crystals are represented by a quartet of orientations related with the initial Goss orientation by a rotation around [011], [01 $\bar 1$ ], [101], and [10 $\bar 1$ ] axes at an angle of ～30°. The crystallographic relationship between the initial and final grain orientations can be explained by their closeness to special misorientations as follows: Σ9, Σ19a, Σ27a, and Σ33a (rotation around 〈110〉 axes to close angles).