Connecting the Precipitation Behaviors on Internal Cavity Surfaces and External Surfaces in an Al–Si Alloy

Metallurgical and Materials Transactions A - Whether the cavity filling efficiency of surface segregation alloys can be quantitatively reproduced by external surface precipitations remains unclear....     

Effect of Impurities and Ce on the Anisotropic Behavior of 8090 Alloy Sheet

ＥｆｆｅｃｔｏｆＩｍｐｕｒｉｔｉｅｓａｎｄＣｅｏｎｔｈｅＡｎｉｓｏｔｒｏｐｉｃＢｅｈａｖｉｏｒｏｆ８０９０ＡｌｌｏｙＳｈｅｅｔ￥ＭｅｎｇＬｉａｎｇ；ＧｅｎｇＤｏｎｇｓｈｅｎｇ；ＺｈｅｎｇＸｉｕｌｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌＳｃｉｅｎ...     

Influence of Aging Treatment on Precipitation Behavior of η Phase in Ni-Co-Cr Alloy

The influence of aging treatment on precipitation behavior of -η phase in a new Ni-Co-Cr fastener superal-loy, AEREX350, was investigated by means of optical microscopy, scanning electron microscopy (SEM) and trans-mission electron microscopy (TEM). The precipitation behavior of η phase with two kinds of morphologies in this material was found to be sensitive to the temperature and time of aging treatment. Time-temperature-transformation curves of these two η phase were achieved. Furthermore, diffraction patterns revealed the semi-coherent orientation relationship between η phase and γ matrix. This approach may be used to optimize the microstructure of the alloy for excellent mechanical properties.     

Behavior of Cerium Addition in the Binary Fe-28Al Alloy

ｎｔｅｒｍｅｔａｌｉｃｓｂａｓｅｄｏｎＦｅ３Ａｌａｆｏｒｄｅｘｃｅｌｅｎｔｏｘｉｄａｔｉｏｎｒｅｓｉｓｔａｎｃｅｐｒｏｐｅｒｔｉｅｓａｔｒｅｌａｔｉｖｅｌｙｌｏｗｃｏｓｔａｎｄｍａｔｅｒｉａｌｓｄｅｎｓｉｔｙ，ｍａｋｉｎｇｔｈｅｍｃａｎｄｉｄａｔｅｓ...     

Influence of Heating and Cooling on the Isothermal β → ω Transition in Ti–22Nb–6Zr Alloy

Russian Journal of Non-Ferrous Metals - The influence of heating and cooling routes prior to aging of the Ti–22Nb–6Zr shape memory alloy (at %) on the intensity of formation of the...     

The Effect of Precipitation Characteristics on Hardening Behavior in Cu–Cr–Sn Alloy with Sn Variation

Powder Metallurgy and Metal Ceramics - The influence of minor solute additions of Sn on hardening behavior and microstructure evolution of the Cu–Cr–Sn alloys has been investigated with...     

Feasibility of Substituting Cerium-Rich Metal by La-Pr-Ce Alloy in Magnesium Alloy

In magnesium alloy ZM3, using cheap Lanthanum-praseodymium-cerium (LPC) rare earth as a substitute for rich-cerium rare earth was studied. The experimental results show that when the adding amount of LPC is between 2.53% and 3.33%, the tensile strength increases as the adding amount of LPC increases; when the amount of RE is 2.53% and 3.33%, the average tensile strength is 142.35, 153.65 MPa respectively. The results show that LPC rare earth replacing rich Ce rare earth is feasible for the tensile strength of ZM3.     

Effect of Cerium on Gas Evolution Behavior of Pb-Ca-Sn Alloy

Hydrogen and oxygen evolution reactions areharmful to the valve regulate lead acid battery duringcharging and discharging processes.Oxygen evolutionreaction occurs at the positive electrode in the leadacid battery and transfers from baffle to the negativeelectrode,reducing to water finally.Hydrogen evolu-tion reaction takes place occasionally on the negativeelectrode inthe lead acid battery.In general,the rateof hydrogen oxidation reaction on the negative elec-trode is lower or less hydrogenis…     

Influence of Aging Treatment on Precipitation Behavior of η Phase in a Ni-Co-Cr Alloy

 The influence of aging treatment on precipitation behavior of η phase in a new Ni-Co-Cr fastener superalloy, AEREX350, was investigated by means of optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The precipitation behavior of η phase with two kinds of morphologies in this material was found to be sensitive to the temperature and time of aging treatment. Time temperature transformation curves of these two η phase were both achieved. Furthermore, diffraction patterns revealed the semi-coherent orientation relationship between η phase and γ matrix. This approach may be used to optimize the microstructure of the alloy for excellent mechanical properties.     

Low-Cyclic Fatigue Behavior of Peak-Aged Mg–Nd-Based Alloy

Metallurgical and Materials Transactions A - In low cycle fatigue, Mg–Nd based alloys exhibit initial cyclic hardening and then softening. The cyclic hardening and softening behaviour of a...     

A Study on the Oxidation Behavior of Nb Alloy (Nb-1 pct Zr-0.1 pct C) and Silicide-Coated Nb Alloys

In the current work, silicide coatings were produced on the Nb alloy (Nb-1 pct Zr-0.1 pct C) using the halide activated pack cementation (HAPC) technique. Coating parameters (temperature and time) were optimized to produce a two-layer (Nb₅Si₃ and NbSi₂) coating on the Nb alloy. Subsequently, the oxidation behavior of the Nb alloy (Nb-1 pct Zr-0.1 pct C) and silicide-coated Nb alloy was studied using thermogravimetric analysis (TGA) and isothermal weight gain oxidation experiments. Phase identification and morphological examinations were carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. TGA showed that the Nb alloy started undergoing accelerated oxidation at and above 773 K (500 °C). Isothermal weight gain experiments carried out on the Nb alloy under air environment at 873 K (600 °C) up to a time period of 16 hours exhibited a linear growth rate law of oxidation. In the case of silicide-based coatings, TGA showed that oxidation resistance of silicide coatings was retained up to 1473 K (1200 °C). Isothermal weight gain experiments on the silicide coatings carried out at 1273 K (1000 °C) in air showed that initially up to 8 hours, the weight of the sample increased, and beyond 8 hours the weight of the sample remained constant. The oxide phases formed on the bare samples and on the coated samples during oxidation were found to be Nb₂O₅ and a mixture of SiO₂ and Nb₂O₅ phases, respectively. SEM showed the formation of nonprotective oxide layer on the bare Nb alloy and a protective (adherent, nonporous) oxide layer on silicide-coated samples. The formation of protective SiO₂ layer on the silicide-coated samples greatly improved the oxidation resistance at higher temperatures.     

Electrochemical Investigation on the Formation of Dy-Fe Alloy in Molten Chlorides

ＥｌｅｃｔｒｏｃｈｅｍｉｃａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＦｏｒｍａｔｉｏｎｏｆＤｙＦｅＡｌｏｙｉｎＭｏｌｔｅｎＣｈｌｏｒｉｄｅｓＬｉｕＧｕａｎｋｕｎ（刘冠昆），ＴｏｎｇＹｅｘｉａｎｇ（童叶翔），ＨｏｎｇＨｕｉｃｈａｎ（洪惠婵），Ｙａｎｇ...     

Phase Equilibria in Liquid Metal of the Cu–Al–Cr–O System

A thermodynamic analysis of phase equilibria in the Cu–Al–Cr–O system is carried out. Thermodynamic modeling of the liquidus surface of the Cu₂O–Al₂O₃–Cr₂O₃ oxide phase diagram is performed. To describe activities of an oxide melt, the approximation of the theory of subregular ionic solutions, the energy parameters of which were determined during modeling, is used. Melting characteristics of the CuCrO₂ compound are also evaluated in the course of the calculation. Coordinates of invariant equilibria points implemented in the Cu₂O–Al₂O₃–Cr₂O₃ ternary oxide system are established by the results of the calculation. Thermodynamic modeling of interaction processes in the Cu–Al–Cr–O system in occurrence conditions of a copper-based metal melt is also performed. The temperature dependence of the equilibrium constant of the reaction that characterizes the formation of the CuCrO₂ solid compound from components of the metal melt of the Cu–Al–Cr–O system is determined. The temperature dependence for the first-order interaction parameter (by Wagner) of chromium and oxygen dissolved in liquid copper is found. The results of thermodynamic modeling for the Cu–Al–Cr–O system are presented in the form of the solubility surface of components in metal, which makes it possible to attribute the quantitative variations in the metal melt concentration with qualitative variations in the composition of forming interaction products. It is determined by the results of modeling that particles of the |Al₂O₃, Cr₂O₃|_sol.sln solid solution are formed at valuable aluminum and chromium concentrations in the copper melt of the Cu–Al–Cr–O system as the main interaction product. The results of the investigation can be interesting for improving the technology process of smelting of chromium bronzes.     

SHS Metallurgy of Composite Materials Based on the Nb–Si System

Composite materials (CMs) based on niobium with functional and alloying additives (Si, Hf, Ti, Al, etc.) have prospects for industrial approval in aviation propulsion engineering. The authors previously showed that such CMs can be synthesized in an autowave mode (combustion mode) using highly exothermic mixtures of Nb₂O₅ with Al, Si, Hf, and Ti. It was found that hafnium actively participates in the reduction of Nb₂O₅, which complicates its introduction into the CM. This study is directed at investigating the possibility to synthesize Nb-based composite materials with a high Hf content using methods of centrifugal SHS metallurgy. It is shown in experimental investigations using a centrifugal installation under the effect of acceleration of 40 g that the replacement of active Hf by its less active compounds Hf–Al or Hf–Ti–Si–Al in the composition of the Nb₂O₅/Al mixtures makes it possible to transfer the combustion of the mixture from the explosion-like mode into the steady-state combustion mode. The content of Hf in the CM increases with an increase in the size of Hf–Al granules from 0–40 to 160–300 μm from 1.3 to 3.8 wt %. The introduction of Hf–Ti–Si–Al granules with a particle size from 1 to 3 mm into the initial charge makes it possible to form cast CMs based on niobium silicides with a Hf content up to 8.1 wt %. The integral composition and distribution of base and impurity elements in structure components of cast CMs, as well as their phase composition, were determined using electron microscopy and X-ray phase analysis. CMs with the maximal Hf content (8.1 wt %) contain three structural components: (1) the base, which includes Nb, Si, and Ti; (2) intergrain boundaries containing Nb, Ti, and Al; and (3) inclusions based on hafnium oxide. Three phases are revealed in the X-ray diffraction pattern of the CM, notably, solid solutions based on Nb and Nb5Si3, as well as a minor amount of Nb₃Si.     

Effect of Zr Content on the Microstructure and Corrosion Resistance of Al–Cu–Mn Alloy

Russian Journal of Non-Ferrous Metals - In order to improve the overall properties of cast Al–Cu–Mn alloy, the effect of Zr content on the microstructure and corrosion resistance of...     

Effect of Electrodeposition Current and Pulse Parameter on Surface Mechanical and Electrochemical Behavior of Ni–W Alloy Coatings

Metallurgical and Materials Transactions A - Ni–W alloy coatings have various applications because they are capable of replacing hard chromium coatings due to their corrosion, oxidation,...