Effect of pre-annealing treatment temperature on compactibility of gas-atomized Al-27%Si alloy powders was investigated. Microstructure and hardness of the annealed powders were characterized. Pre-annealing results in decreasing Al matrix hardness, dissolving of needle-like eutectic Si phase, precipitation and growth of supersaturated Si atoms, and spheroidisation of primary Si phase. Compactibility of the alloy powders is gradually improved with increasing the annealing temperature to 400 °C. However, it decreases when the temperature is above 400 °C owing to the existence of Si-Si phase clusters and the densely distributed Si particles. A maximum relative density of 96.1% is obtained after annealing at 400 °C for 4 h. In addition, the deviation of compactibility among the pre-annealed powders reaches a maximum at a pressure of 175 MPa. Therefore, a proper pre-annealing treatment can significantly enhance the cold compactibility of gas-atomized Al-Si alloy powders.

The development of low-energy consumption and environmentally friendly electrodeposition of metal/alloy films or coatings is presently one of the primary topics for the research community. For this purpose, deep eutectic solvents (DESs) are valued as electrolytes for their advantages of low operating temperature and wide electrochemical windows. At present, there is large amount of literature on this emerging field, but there are no specialized reviews of these studies. Here, after a brief introduction of DESs’ concept and history, we comprehensively reviewed the lastest progress on the metal/alloy electrodeposition in DESs. Additionally, we discussed the key influence factors of the electrodeposition process and analyzed the corresponding mechanisms. Based on these, we emphasized the importance of the establishment of predictive models for dealing with the challenges in large-scale applications.

The phase diagram of ZrO₂-CaO-TiO₂ system was essential for the development of photocatalytic materials and refractory materials. In this work, the ZrO₂-CaO-TiO₂ system was accessed by using the CALPHAD method. The substitutional solution models were used to describe liquid and solid solution phases, the sub-lattice models were used to describe ternary compounds, and then the thermodynamic parameters were obtained by the least square method combined with literature experiment results. The acquired thermodynamic parameters were used to calculate the isothermal sections of the ZrO₂-CaO-TiO₂ system at 1473 and 1673 K.There existed a good agreement between experimental and predicted phase relationships, the experimental points which were inconsistent with calculated results may be attributed to experimental errors and the sluggish kinetics of cations for ZrO₂-based materials. In order to further verify the validity of the database, the thermodynamic parameters were also used to simulate the thermodynamic properties (specific heat capacity, enthalpy, and entropy) of CaZrTi₂O₇ within 5% errors. Good consistency demonstrated that the present thermodynamic database was self-consistent and credible.

The thermodynamics in zinc hydrometallurgical process was studied using a chemical equilibrium modeling code (GEMS) to predict the zinc solubility and construct the species distribution and predominance diagrams for the Zn(II)-NH₃-H₂O and Zn(II)-NH₃-Cl^--H₂O system. The zinc solubilities in ammoniacal solutions were also measured with equilibrium experiments, which agree well with the predicted values. The distribution and predominance diagrams show that ammine and hydroxyl ammine complexes are the main aqueous Zn species,  is predominant in weak alkaline solution for both Zn(II)-NH₃-H₂O and Zn(II)-NH₃-Cl^--H₂O systems. In Zn(II)-NH₃-Cl^--H₂O system, the ternary complexes containing ammonia and chloride increase the zinc solubility in neutral solution. There are three zinc compounds, Zn(OH)₂, Zn(OH)_1.6Cl_0.4 and Zn(NH₃)₂Cl₂, on which the zinc solubility depends, according to the total ammonia, chloride and zinc concentration. These thermodynamic diagrams show the effects of ammonia, chloride and zinc concentration on the zinc solubility, which can provide thermodynamic references for the zinc hydrometallurgy.

A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro- and nano-crystalline multilayered ultra-smooth diamond (USCD) film on the interior-hole surface of WC-Co drawing dies with aperture ranging from d1.0 mm to 60 mm. Characterization results indicate that the surface roughness values (R_a) in the entry zone, drawing zone and bearing zone of as-fabricated USCD coated drawing die were measured as low as 25.7, 23.3 and 25.5 nm, respectively. Furthermore, the friction properties of USCD films were examined in both dry sliding and water-lubricating conditions, and the results show that the USCD film presents much superior friction properties. Its friction coefficients against ball-bearing steel, copper and silicon nitride balls (d4 mm), is always lower than that of microcrystalline diamond (MCD) or WC-Co sample, regardless of the lubricating condition. Meanwhile, it still presents competitive wear resistance with the MCD films. Finally, the working lifetime and performance of as-fabricated USCD coated drawing dies were examined under producing low-carbon steel pipes in dry-sliding and water-lubricating conditions. Under the water-lubricating drawing condition, its production significantly increases by about 20 times compared with the conventional WC-Co drawing dies.

The effects of temperature, ammonia concentration and ammonium carbonate concentration on the dissolving behavior of ammonium paratungstate were studied in (NH₄)₂CO₃-NH₃？H₂O-H₂O system. The results show that rising temperature, prolonging duration, increasing ammonia concentration and decreasing ammonium carbonate concentration favor dissolving of ammonium paratungstate at temperature below 90 °C, while the WO₃ concentration decreases after a certain time at temperature above 100 °C. Furthermore, the undissolved tungsten exists in the form of either APT·4H₂O below 90 °C or pyrochlore-type tungsten trioxide above 100 °C. In dissolving process, the ammonium paratungstate dissolves into paratungstate ions followed by partially converting to tungstate ion, resulting in the coexistence of the both ions. This study may provide a new idea to exploit a novel technique for manufacturing ammonium paratungstate and pyrochlore-type tungsten trioxide.

The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.

The microstructure and mechanical properties of 2524 Al alloy after quenching in liquid nitrogen (LN₂) were investigated by TEM and compared with those of cold water quenching. The results show that the LN₂ quenching process effectively induces the formation of dislocation loops. These loops become large and unevenly distribute after aging for 15 min. Furthermore, such loops become rapidly immobilized by the precipitation of coarse S phases after 1 h aging. The alloy quenched in LN₂ demonstrates superior peak hardness and displays a more rapid response to subsequent aging treatments compared with the cold water-quenched one. Despite the short aging time, LN₂-quenched sample achieves tensile strength of 488 MPa. This enhanced strength is attributed to the strengthening effect of numerous finely dispersed Guinier-Preston-Bagaryatsky (GPB) zones, in conjunction with the inhomogeneous formation of S phase on the dislocation loops.

A novel method, bath smelting process, was developed to treat molybdenite concentrate aiming at the existing problems of traditional process. To understand the dissolving behavior of MoS₂ in white matte, the binary phase diagram of Cu₂S-Mo₂S was measured by the cooling curve method. The result shows that this system is a simple binary eutectic with a eutectic temperature of (1117.0±3.0) °C and a eutectic composition of (1.70±0.20)% MoS₂ in mass fraction. When the MoS₂ addition exceeds 4.48%, MoS₂ and Cu₂S can form the ternary compound containing CuMo₂S₃ or Cu₂Mo₆S₈. In the temperature range of copper smelting, 1200-1300 °C, molybdenite can dissolve in the cuprous sulfide. At 1200 °C, the solubility of molybdenite can reach 14.8%.

Nanocrystalline Ni-Fe FCC alloy coatings with Fe content of 1.3%-39% (mass fraction) were fabricated on the nickel substrates using a DC electrodeposition technique. The crystal structure, lattice strain, grain size and lattice constant of the Ni-Fe alloy coatings were studied by X-ray diffraction technique. The chemical composition and surface morphology of the FCC Ni-Fe alloy coatings were investigated with the energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM). The results show that the Fe content of the Ni-Fe alloy coatings has a great influence on the preferred orientation, grain size, lattice constant and lattice strain. FCC Ni-Fe alloy coatings exhibit preferred orientations of (200) or (200)(111). With an increase of Fe content, the preferred growth orientation of (200) plane is weakened gradually, while the preferred growth orientation of (111) increases. An increase of the Fe content in the range of 1.3%-25% (mass fraction) results in a significant grain refinement of the coatings. Increasing the Fe content beyond 25% does not decrease the grain size of FCC Ni-Fe alloys further. The lattice strain increases with increasing the Fe content in the FCC Ni-Fe alloys. Since the alloys with Fe content not less than 25% has similar grain size (~11 nm), the increase in the lattice strain with the increase of Fe content cannot be attributed to the change in the grain size.

The interaction between molten Na₂CO₃-NaCl salt and Sb and the solubility of Sb in molten salt were investigated in the temperature range of 700-1000 °C. The results show that the dissolution equilibrium of Sb in molten salt can be achieved in 3 h, and the amount of Sb dissolved in the melt decreases as the viscosity decreases. The solubility limits in an eutectic mixture were determined as 5.42%, 2.42%, 0.75% and 0.68% at 700, 800, 900 and 1000 °C, respectively. A high temperature and appropriate content of NaCl will decrease the dissolution of Sb. The insoluble Sb was collected at the bottom of molten salt. The Sb dissolved on the surface of the molten salt is easily oxidized, whereas the Sb dissolved inside the molten salt is randomly distributed in terms of the form of metal Sb.

W-doped LiNi_0.88Co_0.09Mn_0.03O₂ cathodes were fabricated by using W-doped precursors. X-ray diffraction indicates that W-doping suppresses the crystal growth of the precursor along the direction perpendicular to c-axis. Scanning electron microscopy results show that the primary particles of the cathode become finer with the increase of W-doping amount. Electrochemical measurements prove the merits of the W-doped cathodes. The one with 0.4 wt.% W-doping shows significantly improved electrochemical properties compared with the pristine one. After 100 charge-discharge cycles at a high rate of 10C, it exhibits capacity retentions of 94.68% and 89.63% at 25 and 45 °C, respectively. The intergranular cracks after cycles are also suppressed by W-doping. Hence, profiting from the synergistic effect of component regulation and microstructure engineering by W-doping, the Li⁺ diffusion kinetics is boosted, and the structural stability is enhanced.

The service performance of Al alloy sheets can be improved by controlling the rolling temperature. In this study, the corrosion resistance of Al-Mg-Mn-Sc alloy sheets was enhanced through cryorolling (CR). The corrosion resistance of the CR samples with 50% rolling reduction was superior to that of the room-temperature rolled (RTR) samples. After the sensitization treatment (ST), the maximum intergranular corrosion (IGC) depth for the CR samples was 35.2 μm, while it was 53.9 μm for the RTR samples. Similarly, the mass losses were 56.89 and 73.11 mg/cm² for the CR and RTR samples after ST, respectively. In addition, the impedance modulus of the CR sample was more than twice that of the RTR sample. Superior pitting resistance can be attributed to the thicker passivation film and the Al₆(Mn,Fe) phases being broken and interspersed in CR samples. Furthermore, the sub-grains, shear bands, dispersive Al₃(Sc,Zr) phases, fewer high-angle grain boundaries and high-density dislocations in the CR samples impeded the continuous precipitation of the β (Al₃Mg₂) phase along grain boundaries while promoting its formation inside grains instead. These microscopic characteristics significantly reduced the electrical coupling effect between β phase and the Al matrix, leading to a considerable decrease in IGC occurrence.

Silicon/flake graphite/carbon (Si/FG/C) composites were synthesized with different dispersants via spray drying and subsequent pyrolysis, and effects of dispersants on the characteristics of the composites were investigated. The structure and properties of the composites were determined by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The results show that samples have silicon/flake graphite/amorphous carbon composite structure, good spherical appearances, and better electrochemical performance than pure nano-Si and FG/C composites. Compared with the Si/FG/C composite using washing powder as dispersant, the Si/FG/C composite using sodium dodecyl benzene sulfonate (SDBS) as dispersant has better electrochemical performance with a reversible capacity of 602.68 mA·h/g, and a capacity retention ratio of 91.58 % after 20 cycles.

The corrosion behavior of the Cu-Ti alloys with different Ti contents in 3.5% (mass fraction) NaCl solution was investigated using electrochemical measurements, immersion tests, mass loss measurements and SEM observation. The results show that Ti dissolved in the Cu matrix changes the corrosion process of the alloys. Pure Cu sample exhibits a typical active–passive- transpassive corrosion behavior. The anodic polarization current densities of the Cu-Ti alloys steadily increase with increasing applied potential, indicating that active dissolution of copper proceeds due to the potential difference in the galvanic coupling of Cu and Ti. The increase of Ti content decreases the corrosion resistance of the Cu-Ti alloys.

For the low-grade gibbsitic bauxite, the leaching rate of alumina is very low during the Bayer process. The acid leaching method is attracting more attention, and the hydrochloric acid leaching was developed rapidly. The mineral composition and chemical composition were investigated by X-ray diffraction analysis and semi-quantitative analysis. The thermodynamics of leaching process was analyzed. The results show that the major minerals in the bauxite are gibbsite, secondly goethite and quartz, anatase and so on. The acid leaching reactions of the bauxite would be thermodynamically easy and completed. Under the conditions that ore granularity is less than -55 μm, the L/S ratio is 100:7, and the leaching temperature is 373-383 K, the leaching time is 120 min and the concentration of HCl is 10%, both the leaching rates of Al and Fe are over 95%. The main composition of leaching slag is SiO₂ which is easy for comprehensive utilization.

The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses, including electrical conductivity, mechanical properties, local corrosion properties, and slow strain rate tensile stress corrosion tests. Microstructure characterization techniques such as metallographic microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were also employed. The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging, and it even exceeds 700 MPa. Furthermore, the yield strength increases by 52.7 MPa, reaching 654.8 MPa after T6I6 aging treatment. The maximum depths of intergranular corrosion (IGC) and exfoliation corrosion (EXCO) decrease from 116.3 and 468.5 μm to 89.5 and 324.3 μm, respectively. The stress corrosion factor also decreases from 2.1% to 1.6%. These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance. Similarly, when the alloy is treated with T6I4, T6I6 and T6I7 aging, the sizes of grain boundary precipitates (GBPs) are found to be 5.2, 18.4, and 32.8 nm, respectively. The sizes of matrix precipitates are 4.8, 5.7 and 15.7 nm, respectively. The atomic fractions of Zn in GBPs are 9.92 at.%, 8.23 at.% and 6.87 at.%, respectively, while the atomic fractions of Mg are 12.66 at.%, 8.43 at.% and 7.00 at.%, respectively. Additionally, the atomic fractions of Cu are 1.83 at.%, 2.47 at.% and 3.41 at.%, respectively.

In order to have a better understanding on the corrosion mechanisms of bulk two-phase Ag-25Cu (at.%) alloys with different microstructures, two bulk nanocrystalline Ag-25Cu alloys and one coarse grained counterpart were prepared by liquid phase reduction (LPR), mechanical alloying (MA) and powder metallurgy (PM) methods, respectively. Their corrosion behavior was investigated comparatively using electrochemical methods in NaCl aqueous solution. Results show that the microstructure of the coarse grained PMAg-25Cu alloy is extremely inhomogeneous. On the contrary, compared with PMAg-25Cu alloy, the microstructures of the nanocrystalline LPRAg-25Cu and MAAg-25Cu alloys are more homogeneous, especially for LPRAg-25Cu alloy. The corrosion rate of MAAg-25Cu alloy is higher than that of PMAg-25Cu alloy, but lower than that of LPRAg-25Cu alloy. Furthermore, the passive films formed by three Ag-25Cu alloys exhibit n-type semiconducting properties. The passive current density of LPRAg-25Cu alloy is lower than that of PMAg-25Cu alloy, but higher that of MAAg-25Cu alloy.

The microstructural characteristics, mechanical properties and creep resistance of Mg-(8%-12%)Zn-(2%-6%)Al alloys were investigated to get a better overall understanding of these series alloys. The results indicate that the microstructure of the alloys ZA82, ZA102 and ZA122 with the mass ratio of Zn to Al of 4-6 is mainly composed of α-Mg matrix and two different morphologies of precipitates (block τ-Mg₃₂(Al, Zn)₄₉ and dense lamellar e-Mg₅₁Zn₂₀), the alloys ZA84, ZA104 and ZA124 with the mass ratio of 2-3 contain α-Mg matrix and only block τ phases, and the alloys ZA86, ZA106 and ZA126 with the mass ratio of 1-2 consist of α-Mg matrix, block τ precipitates, lamellar f-Al₂Mg₅Zn₂ eutectics and flocculent β-Mg₁₇Al₁₂ compounds. The alloys studied with the mass ratio of Zn to Al of 2-3 exhibit high creep resistance, and the alloy ZA124 with the continuous network of τ precipitating along grain boundaries shows the highest creep resistance.

Double glow plasma surface metallurgy technique was used to fabricate a Fe-Al-Cr-Nb alloyed layer onto the surface of the 45 steel. The microstructures and composition of the Fe-Al-Cr-Nb alloyed layer were analyzed by scanning electronic microscopy, X-ray diffraction and energy dispersive spectroscopy. The results indicate that the 20 μm alloyed layer is homogeneous and compact. The alloyed elements exhibit a gradient distribution along the cross section. Microhardness and nanoindentation tests imply that the surface hardness of the alloyed layer reaches HV580, which is almost 2.8 times that of the substrate. Compared with the substrate, the alloyed layer has a much smaller displacement and a larger elastic modulus. According to the friction and wear tests at room temperature, the Fe-Al-Cr-Nb alloyed layer has lower friction coefficient and less wear mass, implying that the Fe-Al-Cr-Nb alloyed layer can effectively improve the surface hardness and wear resistance of the substrate.

Ni–Co coatings with various cobalt contents were electrodeposited from modified Watts bath. The effect of cobalt content on electrodeposition mechanism of the coatings was studied by electro-chemical impedance spectroscopy method (EIS). Surface morphology and crystallographic structure of the coatings were investigated by means of SEM and XRD. Mechanical properties of the coatings were determined using Vickers microhardness and tensile tests. It was found that with increasing the Co²⁺ ions in electroplating bath, the charge transfer resistance (R_ct) of Ni-Co film increased whereas the Warburg impedence decreased. This may be due to enhancement in coverage of cathode surface by Co(OH)₂ and higher diffusion rate of metal ions towards cathode surface, respectively. Also, with increasing the cobalt content in the bath, cobalt content in the alloy coating increased anomalously and (111) texture consolidated gradually. With increasing the cobalt content up to 45% in alloy coating, the grain size decreased and consequently, hardness and strength of the alloy increased. Further enhancement of cobalt content up to 55% led to a little decrease in hardness and strength. The maximum ductility was observed for Ni-25%Co coating due to relatively small grain size and compact structure.

The effect of different refining processes on inclusions and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy was investigated, including two-stage hexachloroethane (C₂Cl₆) refining process, two-stage rotating gas bubbling refining process and two-stage composite refining process. It was found that the two-stage composite refining process, which combined C₂Cl₆ and rotating gas bubbling, can significantly improve the melt purity and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy. Compared to the unrefined alloy, the volume fraction of gas porosity defects and slag inclusions decreased from 1.47% to 0.12%, and the yield strength, ultimate tensile strength and elongation of as-quenched alloy increased from 113 MPa,179 MPa and 3.9% to 142 MPa, 293 MPa and 18.1%, respectively. C₂Cl₆ was first utilized to degas and remove large size slag inclusions before lithium addition, and then the rotating gas bubbling was utilized to do the further degassing and remove the suspended fine inclusions after lithium addition. The two-stage composite refining process can take advantage of two methods and get the remarkable refining effect.

The impact of Fe content on the microstructures and mechanical properties of an ultra-high strength aluminum alloy, namely, Al-10.50Zn-2.35Mg-1.25Cu-0.12Cr-0.1Mn-0.1Zr-0.1Ti, was investigated. It is found that the increase of Fe content leads to a notable rise in the volume fraction of microscale secondary phases, including (Cu,Fe,Mn,Cr)Al₇, σ phase (composed of Al, Zn, Mg, and Cu elements), and Al₃(Zr,Ti). The formation of these secondary phases results in the depletion of certain phase-forming elements, thereby significantly reducing the quantity of strengthening phases. Fe imposes minimal impact on tensile strength, but it can significantly alter the elongation (δ). For instance, the average elongation of the alloy with 0.18 wt.% Fe (δ=4.5%) is less than half that of the alloy with Fe less than 0.1 wt.% (δ=9.9%-10.9%). The reduction in elongation is attributed to the combined effects of the formation of coarse secondary phases and the diminished quantity of strengthening phases around these coarse phases.

Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS). The results reveal that the anodic behaviors and reaction kinetics of the two anodes vary a lot during the anodic polarization which indicate the formation and stabilization of anodic layer. Compared with conventional Pb-0.8%Ag anode, Al/Pb-0.8%Ag anode has longer time of anodic polarization. At the very beginning of anodic polarization, the two anodes all exhibit higher potential of oxygen evolution reaction (OER) since the reaction is controlled by the transformation step of intermediates. Then, its OER potential is largely diminished and OER rate is deduced from the formation and adsorption of the first intermediate (S-OH_ads). In the prolonged anodic polarization, the anodic potential of Al/Pb-0.8%Ag gradually decreases and the final value is more stable than that of conventional Pb-0.8%Ag anode. On the anodic layer after 24 h of anodic polarization, the OER potential is controlled by the formation and adsorption of intermediate. The microstructures of Al/Pb-0.8%Ag and Pb-0.8%Ag anodes after 24 h of anodic polarization were analyzed by scanning electron microscope (SEM).

The effect of grinding on the spodumene flotation was investigated. The flotation response of spodumene ground by different mills was different, due to the variation of metal ions on spodumene surfaces caused by grinding environments and/or impurities. The samples were subjected to acid pickling treatment to remove most of the metal ions from the surfaces, and then all samples showed the same poor flotation response, which confirmed the significance of surface metal ions. Metal ion impurities may come from both grinding environments and lattice substitutions in spodumene. Density functional theory (DFT) calculation revealed that Fe and Ca could exist as lattice substitutions on the spodumene surface while Mg substitution is unlikely to occur. Furthermore, Fe is considered to be active site for the absorption of sodium oleate on the spodumene surface. Morphology analysis showed differences in particle size and shape for samples ground by different mills, resulting in different amounts of exposed surfaces. The particle size, cleavage characteristics caused by grinding environments, and metal ion impurities originated from grinding and isomorphous substitutions, play significant roles in the chemisorption of collector on the spodumene surface.

The effect of high pressure on the microstructure and microsegregation of Mg-11Al (mass fraction, %) alloys was studied through experiments and first-principles calculations. The results show that the Al content in the initial solid phase is high owing to the high solute partition coefficient and the large undercooling in the alloys solidified under pressures of 4-6 GPa, and the Al content in the initial solid phase increases with the increase of pressure. Consequently, the total amount of excess solute in the liquid phase in the final solidification stage decreases with increasing pressure, thus decreasing or suppressing the eutectic transformation. Furthermore, the microstructure of the alloys solidified under pressures of 5-6 GPa is a fine-grained solid solution, consisting of grains with high solubility of Al atoms and grain boundaries with abundant Al solutes. As the pressure increases, the grain boundary doping energy of Al atoms decreases, while their grain boundary segregation energy of Al atoms increases, and the charge density between the Mg—Al (Mg) bonds also rises. Therefore, the stability of the microstructure is improved, and the bond strength of grain boundaries is enhanced.

Four different methods, namely mineralogical analysis, three-stage BCR sequential extraction procedure, dynamic leaching test and Hakanson Potential Ecological Risk Index Method were used to access the environmental activity and potential ecological risks of heavy metals in zinc leaching residue. The results demonstrate that the environmental activity of heavy metals declines in the following order: Cd>Zn>Cu>As>Pb. Potential ecological risk indices for single heavy metal are Cd>Zn>Cu>As>Pb. Cd has serious potential ecological risk to the ecological environment and contributes most to the potential toxicity response indices for various heavy metals in the residue.

The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction (SR-XRD) and S, Fe and Cu K_α X-ray absorption near edge structure (XANES) spectroscopy. Leaching experiment showed that 82.4% of Cu²⁺ was dissolved by A. manzaensis after 10 d. The surface of chalcopyrite was corroded apparently and covered with leaching products. During bioleaching, the formation and evolution of secondary minerals were as follows: 1) little elemental sulfur, jarosite, bornite and chalcocite were found at days 2 and 4; and 2) bornite and chalcocite disappeared, covellite formed, and jarosite gradually became the main component at days 6 and 10. These results indicated that metal-deficiency sulfides chalcocite and bornite were first formed with a low redox potential value (360-461 mV), and then gradually transformed to covellite with a high redox potential value (461-531 mV).

The effects of Si content on the microstructure and yield strength of Al-(1.44-12.40)Si-0.7Mg (wt.%) alloy sheets under the T4 condition were systematically studied via laser scanning confocal microscopy (LSCM), DSC, TEM and tensile tests. The results show that the recrystallization grain of the alloy sheets becomes more refined with an increase in Si content. When the Si content increases from 1.44 to 12.4 wt.%, the grain size of the alloy sheets decreases from approximately 47 to 10 μm. Further, with an increase in Si content, the volume fraction of the GP zones in the matrix increases slightly. Based on the existing model, a yield strength model for alloy sheets was proposed. The predicted results are in good agreement with the actual experimental results and reveal the strengthening mechanisms of the Al-(1.44-12.40)Si-0.7Mg alloy sheets under the T4 condition and how they are influenced by the Si content.

Powder metallurgy processes are suitable to produce form-stable solid-liquid phase change materials from miscibility gap alloys. They allow to obtain a composite metallic material with good dispersion of low-melting active phase particles in a high-melting passive matrix, preventing leakage of the particles during phase transition and, therefore, increasing the stability of thermal response. Also, the matrix provides structural properties. The aim of this work is to combine conventional powder mixing techniques (simple mixing and ball milling) to improve active phase isolation and mechanical properties of an Al-Sn alloy. As matter of fact, ball milling of Sn powder allows to reduce hardness difference with Al powder; moreover, ball milling of the two powders together results in fine microstructure with improved mechanical properties. In addition, different routes applied showed that thermal response depends on the microstructure and, in particular, on the particle size of the active phase. In more detail, coarse active phase particles provide a fast heat release with small undercooling, while small particles solidify more slowly in a wide range of temperature. On the other hand, melting and, consequently, heat storage are independent of the particle size of the active phase. This potentially allows to “tailor” the thermal response by producing alloys with suitable microstructure.

The quench sensitivity of 6063 alloy was investigated via constructing time-temperature-property (TTP) curves by interrupted quenching technique and transmission electron microscopy (TEM) analysis. The results show that the quench sensitivity of 6063 alloy is lower than that of 6061 or 6082 alloy, and the critical temperature ranges from 300 to 410 °C with the nose temperature of about 360 °C. From TEM analysis, heterogeneous precipitate β-Mg₂Si is prior to nucleate on the (Al_xFe_ySi_z) dispersoids in the critical temperature range, and grows up most rapidly at the nose temperature of 360 °C. The heterogeneous precipitation leads to a low concentration of solute, which consequently reduces the amount of the strengthening phase β'' after aging. In the large-scale industrial production of 6063 alloy, the cooling rate during quenching should be enhanced as high as possible in the quenching sensitive temperature range (410-300 °C) to suppress the heterogeneous precipitation to get optimal mechanical properties, and it should be slowed down properly from the solution temperature to 410 °C and below 300 °C to reduce the residual stress.

Effects of additions minor contents of 0.03% Sc and 0.12% Zr and solution treatment on microstructure and mechanical properties of Al-9.0Zn-2.8Mg-2.5Cu alloy were studied by metallographic microscopy, differential thermal analysis (DSC) and transmission electron microscopy (TEM), in order to obtain high-performance Al alloys. The minor additions of Sc (less than 0.1%) were carried out. The results show that with the additions of 0.03% Sc and 0.12% Zr, the petaloid Al₃(Sc,Zr) precipitated phases occur in Al-9.0Zn-2.8Mg-2.5Cu alloy, and Al₃(Sc,Zr) particles obviously hinder the recrystallization of Al-9.0Zn-2.8Mg-2.5Cu alloy during homogenizing and extruding processes due to their strong pinning effect on dislocation. Multi-stage solution is better than single solution, for it can avoid recrystallization of Al-9.0Zn-2.8Mg-2.5Cu alloy with the minor contents of Sc (less than 0.1%). The proper solution treatment is (420 °C, 3 h)+(465 °C, 2 h) under which Al-9.0Zn-2.8Mg-2.5Cu-0.12Zr-0.03Sc alloy obtains a tensile strength of 777.29 MPa and a elongation of 11.84%.

Powder charges of micron-size Ni and Al2O3 were utilized to deposit nano-structured Ni-Al2O3 composite coatings on an aluminum plate fixed at the top end of a milling vial using a planetary ball mill. Composite coatings were fabricated using powder mixtures with a wide range of Ni/Al2O3 mass ratio varying from 1:1 to plain Ni. XRD, SEM and TEM techniques were employed to study the structural characteristics of the coatings. It was found that the composition of the starting mixture strongly affects the Al2O3 content and the microstructure of the final coating. Mixtures containing higher contents of Al2O3 yield higher volume fractions of the Al2O3 particles in the coating. Though Ni-Al2O3 composite coatings with about 50% of Al2O3 particles were successfully deposited, well-compacted and free of cracks and/or voids coatings included less than 20% (volume fraction) of Al2O3 particles which were deposited from powder mixtures with Ni/Al2O3 mass ratios of 4:1 or higher. Moreover, mechanical and metallurgical bondings are the main mechanisms of the adhesion of the coating to the Al substrate. Finally, functionally graded composite coatings with noticeable compaction and integrity were produced by deposition of two separate layers under identical coating conditions.

The effects of trace Ag element on the precipitation behaviors and mechanical properties of the Mg-7.5Gd- 1.5Y-0.4Zr (wt.%) alloy by means of tensile test, X-ray diffractometry, scanning electron microscopy, electron backscattered diffractometry, and scanning transmission electron microscopy. There is an unusual texture (á0001？//extrusion direction) in the extruded Mg-Gd-Y-Zr alloys containing 0.5 wt.% Ag. During the aging periods at 225 °C, the addition of the trace Ag does not form new precipitates, just accelerates aging kinetics, and refines β′ precipitates, thereby increasing the number density of the β′ precipitates by Ag-clusters. Moreover, the Mg-Gd-Y-Zr alloy containing 0.5 wt.% Ag shows the most excellent synergy of strength and plasticity (408 MPa of ultimate tensile strength, 265 MPa of yield strength, and 12.9% of elongation to failure) after peak-aging.

Zn-doped TiO₂ (Zn-TiO₂) thin films were prepared by the sol-gel method on titanium substrates with heat treatment at different temperatures. The effects of heat treatment temperatures and Zn doping on the structure, photocathodic protection and photoelectrochemical properties of TiO₂ thin films were investigated. It is indicated that the photoelectrical performance of the Zn-TiO₂ films is enhanced with the addition of Zn element compared with the pure-TiO₂ film and the largest decline by 897 mV in the electrode potential is achieved under 300 °C heat treatment. SEM-EDS analyses show that Zn element is unevenly distributed in Zn-TiO₂ films; XRD patterns reveal that the grain size of Zn-TiO₂ is smaller than that of pure-TiO₂; FTIR results indicate that Zn—O bond forms on Zn-TiO₂ surface. Ultraviolet visible absorption spectra prove that Zn-TiO₂ shifts to visible light region. Mott-Shottky curves show that the flat-band potential of Zn-TiO₂ is more negative and charge carrier density is bigger than that of pure-TiO₂, implying that under the synergy of the width of the space-charge layer, carrier density and flat-band potential, Zn-TiO₂ with 300 °C heat treatment displays the best photocathodic protection performance.

A mathematical model of the particle heating process in the reaction shaft of flash smelting furnace was established and the calculation was performed. The results indicate that radiation plays a significant role in the heat transfer process within the first 0.6 m in the upper part of the reaction shaft, whilst the convection is dominant in the area below 0.6 m for the particle heating. In order to accelerate the particle ignition, it is necessary to enhance the convection, thus to speed up the particle heating. A high-speed preheated oxygen jet technology was then suggested to replace the nature gas combustion in the flash furnace, aiming to create a lateral disturbance in the gaseous phase around the particles, so as to achieve a slip velocity between the two phases and a high convective heat transfer coefficient. Numerical simulation was carried out for the cases with the high-speed oxygen jet and the normal nature gas burners. The results show that with the high-speed jet technology, particles are heated up more rapidly and ignited much earlier, especially within the area of the radial range of R=0.3-0.6 m. As a result, a more efficient smelting process can be achieved under the same operational condition.

Low cycle fatigue (LCF) behavior of laser melting deposited (LMD) TC18 titanium alloy was studied at room temperature. Microstructure consisting of fine lamella-like primary α phase and transformed β matrix was obtained by double annealed treatment, and inhomogeneous grain boundary α phase was detected. Fatigue fracture surfaces and longitudinal sections of LCF specimens were examined by optical microscopy and scanning electron microscopy. Results indicate that more than one crack initiation site can be detected on the LCF fracture surface. The fracture morphology of the secondary crack initiation site is different from that of the primary crack initiation site. When the crack grows along the grain boundary α phase, continuous grain boundary α phase leads to a straight propagating manner while discontinuous grain boundary α phase gives rise to flexural propagating mode.

The residues of salt lake brine from which potassium had been removed were used to extract Rb⁺ and Cs⁺ together with a sulphonated kerosene (SK) solution of 1.0 mol/L 4-tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP). Rb⁺ and Cs⁺ were enriched and separated effectively by precipitating Mg²⁺ before extraction and by scrubbing out K⁺ and Na⁺ repeatedly before stripping. The effects of the volume ratio of organic phase to aqueous extraction phase (O/A), alkalinity of aqueous phase (c(OH)^-), interference from K⁺ and Mg²⁺, and ratio the volume of organic phase to aqueous scrubbing phase (O/A′) were investigated. The experimental brine was extracted optimally by 5-stage extraction with 1.0 mol/L t-BAMBP in SK, c(OH^-)=1 mol/L, and O/A=1:1. The scrubbing yield of rubidium was only about 10.5% when the extraction solvent was washed 3 times with 1×10^-4 mol/L NaOH at O/A′=1:0.5. After 5-stage countercurrent extraction, the final extraction yields of Rb⁺ and Cs⁺ reached 95.04% and 99.80%, respectively.

Friction stir processing (FSP) is a solid-state modification method to process the surface of metals. In this process, due to rotation and traverse motions of a non-consumable tool, metal surface microstructure is refined and its mechanical characteristics are improved. Different methods have been applied to improving the efficiency of FSP. In this research, a new method entitled friction stir vibration processing (FSVP) was presented to enhance the efficiency of FSP. In this method, metal workpiece was vibrated normal to processing line during FSP. Microstructure and mechanical properties including hardness, ultimate tensile strength (UTS) and elongation of Al5052 alloy specimens processed using FSP and FSVP methods were analyzed and compared. The results showed that grain size decreased by about 33% as vibration was applied. It was also observed that ultimate tensile strength as well as hardness increased by about 7% as FSVP was applied. This was related to the enhanced straining of metal surface material as vibration was applied. The increase in straining results in the increase of dislocation density. It leads to more development of high angle grain boundaries due to dynamic recrystallization. The results also showed that UTS and elongation of FSV processed specimens increased as vibration frequency increased.

In order to solve the agglomeration problem in TiCl₄ preparation, a new test in a multistage series combined fluidized bed was studied on a pilot scale. The pilot plant can make full use of titanium slag with a high content of MgO and CaO as the feedstock. Several experimental parameters such as chlorine flow and reaction temperature were discussed and the morphology and components of reaction product were analyzed. According to the results, the conversion rate of TiO₂ is up to 90%. It is found that the combined fluidized bed has good anti-agglomeration ability because the accumulation of MgCl₂ and CaCl₂ on the surface of unreacted slag was carried out of the reactor.