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In this study, interactive alternate forward extrusion (AFE) experiments with varying number of extrusion passes of AZ31 magnesium alloy were carried out. The evolution of microstructure, and texture and their effects on the mechanical properties were studied. The results show that with the increase of loading passes, the grains are significantly refined, and the dynamic recrystallisation (DRX) structure is uniformly distributed in the product, which is the main reason for the increase in microhardness, compressive strength and failure strain. Further, slip and twinning induced DRX behaviour are considered to be the main deformation methods in the early stage of deformation. Whereas continuous DRX is considered to be the main deformation methods for the change in grain morphology in the later stage. During the extrusion process, the deflection angle of the base pole decreases. Finally, the fibre texture is formed; the texture strength is significantly reduced because of the effect of recrystallisation. The AZ31 magnesium alloy interactive AFE process is discussed with respect to the technological experiment and the microstructure deformation, thus providing a vital scientific basis for further application.

Fine grain modification is an important means for preparing lightweight and low-plasticity materials, including magnesium alloys. This paper proposes an accumulative alternating back extrusion (AABE) technique for preparing magnesium alloy materials. Metallographic microscopy and electron backscatter diffraction were used to test the resulting magnesium alloy samples and indicated that AABE can effectively refine microstructure and improve uniformity in local areas of the sample. After one pass of AABE, the upper part of the specimen was mainly characterized by recrystallization, with a high degree of refinement. The lower part showed coexisting recrystallization refinement and twinning refinement, which are less preferable. The mean grain size after applying five passes of AABE was half that of the samples subjected to only one pass. AABE is a novel and effective method for preparing high-performance magnesium alloy materials.

In order to study the corrosion behavior of magnesium alloys of high performance in the simulated seawater by continuous variable cross section direct extrusion (CVCDE), an electrochemical method and weight loss method were used to study the difference between AZ31 magnesium alloys produced by CVCDE with different numbers of interim dies to examine the electrochemical corrosion behavior and corrosion rate at 3.5 wt.% NaCl solution in this paper. Scanning electron microscopy and x-ray diffraction were used to analyze the morphology of corrosion surfaces and the composition of the corrosion products of samples soaked for different times. The results show that after CVCDE with different numbers of interim dies, the size of the microstructure is refined gradually, and the grain orientation is also different; with the increase in the number of interim dies, the thermodynamic corrosion tendencies are different, and the corrosion resistance of samples extruded by conventional extrusion is relatively good; the charge transfer and material transfer process are the two main factors affecting the corrosion rate, which determines the direction of the electrochemical reaction; the corrosion form of the sample extruded by CVCDE is the local corrosion which is the filiform corrosion and pitting corrosion, and the corrosion product is mainly water-insoluble Mg(OH)2.

At present, flexible die medium represented by fluid is mainly used in tube hydropiercing, but it is relatively rare in sheet forming field because of the high requirement of sealing. For this reason, magnetorheological fluid, one of the representatives of intelligent materials, is used as a force transfer medium to provide backpressure for the piercing process of sheet for the first time in this paper, so as to reduce the collapse and improve the quality of fracture surface. The results show that with the increase of internal pressure, the collapse of the area near the cutting edge of punch decreases, the length of burnish zone increases, the aperture is closer to the nominal diameter, and the quality of the hole is significantly improved. The theoretical mechanics model of a single straight chain is established through theoretical analysis, and the magnitude and loading mode of the force exerted on the sheet by magnetic medium are deduced. Through the balanced relationship between punching force and backpressure in the deformed area of sheet, the key parameters affecting the collapse of piercing of sheet are obtained, which has important guiding significance for improving the quality of sheet metal piercing products with magnetic medium.

Traditional curved products are obtained in two steps, which consist of an extrusion process and a bending process. There are many bottlenecks to this, such as long processing cycle, low efficiency, and difficulty in controlling the product quality. In this paper, a new staggered extrusion (SE) process was proposed to obtain magnesium alloy bending products. Bending products can be extruded by a staggered punch which has a step-like structure at one end. The experimental results show that with increased staggered distance (h) of the punch, the bending height of the bending products increased significantly. Compared with traditional extrusion, the grains of the bending products obtained by SE are refined. The increase in h is one of the reasons for the asymmetric distribution of axial velocity at the die exit of AZ31 magnesium alloy bending products. The asymmetric distribution of the flow velocity field of bending products during SE is one of the contributors for the bending characteristics to the bending products. The SE enables the use of extrusion in many applicable fields and enriches the types of bending products.

In order to further enrich the existing manufacturing methods and approaches of magnesium alloy sheet forming, a new process of circumferential extending extrusion forming of magnesium alloy sheet, which focuses on the process principle and characteristics of the method, is proposed in this paper. Through theoretical analysis, technological theoretical models such as the dimension relationship between the original billet and the formed sheet and the extrusion speed were deduced. The circumferential extending extrusion process of AZ31 magnesium alloy sheets was experimented. The results show that the backpressure ring of pure aluminum can change the stress state of the sheet during extending extrusion and effectively restrain the change of sheet thinning trend and cracking defects at the outer edge caused by tensile stress, and the product quality is improved remarkably. According to the actual requirements, the size of the required sheets can be customized. It can be seen from the comparison that as the distance from the axis increases, the average grain size of the product decreases remarkably, and and the degree of recrystallization is higher. Meanwhile, the microstructure is refined. With the maturity of the process, it is expected to provide a new idea for the short-process forming of high-performance lightweight alloy sheets.

In this study, the effects of Ag variations on dynamic recrystallization (DRX), texture, and mechanical properties of ultrafine-grained Mg–3Al–1Zn alloys are investigated. The results suggest that Ag segregation and Al–Zn–Ag clusters form in the Mg matrix with Ag addition less than 1 wt%, which retard DRX and the growth of the DRXed grains. The resulting grain size decreases from 513 to 316 nm. As the Ag addition increases to 2 wt%, the Mg54Ag17 phase precipitates along the grain boundary, which plays an important role in restricting DRXed grain growth via grain boundary pinning effect. The resulting grain size is 375 nm with a bimodal grain size distribution. The extrusion texture of the investigated alloys is in fairly scattered orientation distribution. The weak basal texture and ultrafine grain size lead to the high yield asymmetry ratio. The Ag-containing extruded alloys exhibit an increase in the tensile and compressive properties. The strengthening mechanisms due to grain refinement, dislocations, solid solution, precipitates, solute clusters, and segregation are discussed.

Tensile flow behavior of ultrafine-grained Mg-3Al-Zn alloy processed via mechanical milling, hot-press consolidation followed by extrusion has been determined in the temperature range from 300 K to 523 K and strain rate range from 10−2 to 10−4 s−1. The effects of temperature and strain rate on the work hardening behavior are successfully analyzed by the derived Lukac and Balik expression. The microstructure evolution shows that the dislocation density increases from 1.59×1016 m−2 to 3.04×1016 m−2 in work hardening stage and decreases to 3.97×1015 m−2 in work softening stage, which is in accordance with Lukac and Balik expression. The apparent activation energy value of 66.71 kJ/mol in the strain rate range from 10−2 to 10−4 s−1 at 523 K suggests that the dominant mechanism is GBS accommodated by slip controlled by grain boundary diffusion, which is further proved by the formation of cavities and filaments during tensile test. The analysis of work hardening behavior indicates that dislocation multiplication contributes to the hardening process, while cross slip and climb of dislocations as well as GBS play a role in the softening process.

The ultrafine-grained Mg–3Al–Zn alloys were successfully fabricated by the method of mechanical milling, cold press consolidation and warm extrusion. The effect of extrusion temperature on the microstructure and compression properties of the as-extruded samples has been investigated. The results indicate that with the increase of extrusion temperature from 423 K to 473 K, full dynamic recrystallization (DRX) behavior replaces partial DRX, while the average grain size increases from 246 nm to 499 nm. The uniformly dispersioned nano-MgO particles derived from mechanical milling could significantly enhance the compressive properties of as-extruded samples. The yield strength, ultimate compression strength, and fracture strain of the as-extruded alloy with an average grain size of 246 nm are, respectively, 508.0 MPa, 512.8 MPa and 9.2%. The high strength of the alloy is principally ascribed to ultra-fine grained structure and nano-MgO dispersion strengthening, and the contribution ratios are 23.58% and 62.36%, respectively.

In the current study, the effects of extrusion temperatures on the extrudability, microstructure, recrystallization behavior and mechanical properties of the Mg–3.0Zn–0.2Ca–0.5Y alloy have been systematically investigated. The results show that the magnesium alloy bars with excellent mechanical properties are obtained at the extrusion temperature above 523 K. Both the dynamic recrystallized grain size and fraction increase with an increase in the deformation temperature. The MgY phase particles (>1 μm) contribute to increasing DRX fraction, while the finer I-phase precipitates exert a pinning effect on the movement of grain boundaries and thus suppress the grain growth. The competitive mechanism between the particle-stimulated nucleation and grain boundary pinning determines the final microstructure that strongly affects the mechanical properties of the extruded alloys. The yield strength is improved with the decrease of the DRX grain size by grain boundary strengthening, and the ductility is increased by the enhanced work hardening ability with the increase of the DRX fraction.

The Mg-3.0Zn-0.2Ca (wt.%) alloy has been extruded at temperature range of 25–300 °C and the resulting microstructure, texture and mechanical properties are systematically investigated. The results show that the grain size monotonically increases with the increasing of the extrusion temperature and the texture intensity increases firstly and decreases subsequently. In addition, a large number of nano-scale precipitates are formed in alloys extruded above 250 °C. The weakest basal texture developed in the cold extrusion alloy is related to the deformation twinning, while, the combining effects of activation of multiple deformation mechanisms and dynamic precipitates contribute to developing the weaker basal texture in alloys extruded above 250 °C. A sharp basal texture enhances the yield strength of alloy extruded at 150 °C greatly at the cost of work hardening rate. The highest elongation is achieved in the alloy extruded at 300 °C. The enhanced formability is considered to be associated with the dependence of the weaker basal texture and dynamic precipitates on the strain hardening behavior. Among the multiple strengthening mechanisms, the fine grain strengthening and the solid solution strengthening play a dominant role in the increment of strength for the as-extruded alloys.

Herein, we reported the influences of accumulated direct current annealing (ADA) on the GMI properties and microstructures of Zr-doped melt-extracted (Co 68.15 Fe 4.35 Si 12.25 B 12.25 Zr 3 ) amorphous microwires. There indicated that ADA-ed wires enhanced GMI properties and improved the microstructures remarkably in comparison with as-fabricated wires. The maximum GMI ratio [Δ Z / Z 0 ] max and equivalent magnetic circumferential anisotropy field (EMCAF) of ADA-ed microwires were increased to 256.01% and 4 Oe at 20 MHz, respectively, which are more than nearly 8 and 2 times of 33.62% and 1.6 Oe for as-fabricated wires, respectively. Moreover, the maximum magnetic field response sensitivity ( ξ max ) increased to 372.57%/Oe, which is much higher than the as-fabricated wires of 44.71%/Oe. The remarkable enhancement of GMI performance was considered as the microstructural evolution including structural relaxation, appearance of nano-crystallization, and circumferential arrangement of surface magnetic domains. Nano-crystallization degree and circumferential magnetic domains arrangement were effectively improved by actions of Joule thermal energy and circular magnetic field generated ADA as shown in HRTEM and magnetic force microscope (MFM) analysis. Based on above, both the excellent GMI performances and relatively large ξ max values indicate the ADA is an effective annealing technique for thermal treating the melt-extracted amorphous wires which applied for potentially magnetic sensor in detecting low-intensity magnetic fields.

Powder metallurgy Ti–45Al–10Nb alloys was successfully fabricated by reactive sintering of milled powders at 1350 °C for 2 h in vacuum. The microstructure, in particular, constituent phases, grain size, precipitates of the product was investigated in detail. The results indicate that a double phase γ + α 2 microstructure containing Ti 2 AlC precipitate is obtained under the sintering condition, and the alloy exhibits a fine and homogenous microstructure compared with traditional TiAl base. In fine grain structure, the average grain sizes for the γ and α 2 phases are (2.3±0.05) and (5.6±0.05) μm, respectively. Additionally, numerous dislocations are observed in the alloy, and the dislocation density in γ phase is significantly higher than that in α 2 phase. The formation mechanisms of the dislocation in the present alloy were also discussed in detail.

Based on a comprehensive study of the effect of progressive DC Joule-heating annealing (DJA) on giant magneto-impedance (GMI) properties of melt-extracted amorphous microwires, we systematically analysed the different mechanisms for two types of GMI effect definition. Experimental results show that DJA can improve GMI response characteristics and magnetic field sensitivity (MFS) effectively for both definitions, but ΔZ/Z0 is enhanced much more than ΔZ/Zmax of the as-cast wires. At 20 MHz, the maximum GMI ratios, as denoted by ΔZ/Z0 and ΔZ/Zmax, of DJA microwires are enhanced to 582.59% and 639.13%, while the values for the as-cast wires are 69.09% and 520.48% respectively. Meanwhile, the MFS (ξmax) and equivalent magnetic anisotropy field (Hk) increase to 1346.4%/Oe (ΔZ/Z0), 2927.9%/Oe (ΔZ/Zmax) and 1.1 Oe, respectively. These significant effects of GMI properties as denoted by Z0 are mainly attributed to the change of resistivity (ρdc) for amorphous microwires induced by DJA. Revealing the mechanism of different effects can also result in the development of a micromagnetic field sensor, especially for geomagnetic sensor applications (∼±1.0 Oe).

In order to shorten process flow, improve production efficiency, the continuous variable channel direct extrusion (CVCDE) was used for processing magnesium alloy sheets with high performance, which could control shapes and properties of sheets simultaneously. The results of experimental research showed that, compared with the conventional direct extrusion (CDE) method, the CVCDE method promoted the grain refinement of magnesium alloy sheets, reduced the formation of twins and increased the volume fraction of recrystallized grains. It made the orientation of (0002) basal planes tilt from ND direction by a certain angle, and the angle at which the basal planes tilted from the TD direction was gradually approached to the angle tilted from the ED direction, and the Schmid factor of the basal slip was gradually increased, which made the basal slip easier to be activated. In the magnesium alloy sheets extruded by CVCDE using one interim die, incomplete grain refinement led to uneven microstructure, the dislocation wall was generated in the crystal, the dislocation density was high, and the texture strength was increased. In the magnesium alloy sheets extruded by CVCDE using two interim dies, there were obvious triple grain boundaries, low dislocation density in the crystal and the weaker basal texture. Through the joint effect of grain refinement and texture evolution, the magnesium alloy sheets extruded by CVCDE using two interim dies had lower YS and UTS, and the EI increased by 18% compared with the CDE.

The strain in different regions of the pancake was different during isothermal forging process. Different strain could greatly influenced the forged microstructure. In the present work, the relationships between strain, dynamic recrystallization (DRX) and microstructure in different regions of powder metallurgy Ti–45Al–10Nb alloy during isothermal forging were investigated. The results show that the microstructure from the center to edge of the forged pancake was inhomogeneous due to the degree of DRX. And DRX was related with the degree of strain, large strain can promote DRX.

The TiAl matrix composites reinforced with Ti2AlC particles have been successfully fabricated utilizing the method of hot press consolidation followed by isothermal forging. Microstructures and tensile properties of as-sintered and as-forged conditions were investigated. The results show that the as-sintered composites consist of γ-TiAl, α2-Ti3Al and Ti2AlC phases. Microstructure analysis indicates that the products exhibit inhomogeneous microstructure and the Ti2AlC particles tend to disperse on the grain boundaries. A fine-grain and homogenous microstructure was obtained through isothermal forging. The tensile property of as-forged composites was improved simultaneously, with elongation (δ) increasing from 12.10% to 30.87%. In particular, at 1000 °C, the engineering strain was up to 176%, exhibiting superplasticity.

Staggered extrusion (SE) is a new process to realize an integrative process, combines an extrusion process and a bending process. The SE process can solve bottlenecks of traditional bending products, such as long processes, poor flexibility in manufacturing processes. The staggered distance (h) of the stem is a key parameter to determine bending characteristics and quality of the bending products. The effect of h on the SE process was investigated in this paper. With the increase of h, the extrusion load peak appears delay and decreases obviously. The value of h is directly proportional to the maximum bending height of bending products and inversely proportional to the bending radius. After the SE process, the AZ31 magnesium alloy grains were refined obviously and dynamic recrystallized structures were evenly distributed in bending products. The AZ31 Mg bending products were produced strong extrusion fiber texture by SE process, and texture intensity was higher at {0001} 〈11−20〉 and {10−11} 〈11−23〉. The appearance of twins in AZ31 magnesium alloy bending products had a remarkable impact on the occurrence of dynamic recrystallization (DRX) and texture evolution. The SE process was investigated by technological experiments and microstructure deformation, which provided an important vital scientific basis for further application.

After solution treatment, the Mg-3Zn-0.2Ca-0.5Y alloy was subjected to extrusion at various temperatures and extrusion defects, microstructures and mechanical properties of as-extruded samples were studied in detail. The results show the extrusion temperature has a slight effect on DRXed grain size due to the presence of Y-containing phase with a good thermal-stability. On the contrary, the mechanical properties of as-extruded alloys are remarkably influenced by dynamic recrystallization degrees promoted by extrusion temperatures. A good formability of as-extruded bars with an optimal mechanical properties and fine-grained microstructure was obtained by extrusion at 250°C and the mechanical performances are significantly superior to those of hot-rolled ZK60 obtained at the same temperature. In this paper, the magnesium alloy with fine-grained (30%) and high strength (>250MPa) was fabricated easily by a simple extrusion process.

Pure magnesium bars were prepared by two-pass cumulative high ratio extrusion with as-cast Mg as the original material and then the final as-extruded bars were annealed. The effect of extrusion deformation and annealing treatment on the microstructure, mechanical properties and fracture behaviour of the Mg were investigated by optical microscopy (OM), mechanical properties test and scanning electron microscopy (SEM), respectively. The results show that the grain size is obviously refined by the effect of dynamic recrystallization during the extrusion deformation. Thus the room-temperature mechanical properties and fracture behaviour of the material were significantly improved. After the first extrusion, the coarse as-cast grain size was reduced to 35 μm, and the yield strength (YS), ultimate tensile strength (UTS) and elongation of the bar achieved 84 MPa, 189 MPa, and 12%, respectively. After the further extrusion, the YS of as-extruded bar was over 120 MPa; however, the elongation decreased due to work hardening. Finally the grain size of the as-extruded bar was 9-10 μm after annealing treatment, and its YS, UTS and elongation of the bar achieved 124 MPa, 199 MPa, and 10.7%, respectively. The microstructures and mechanical performance of the material were enhanced obviously.

Powders with nominal composition of Ti-45Al-10Nb (mole fraction, %) were prepared by mechanical ball milling and were then consolidated by hot-pressed sintering in vacuum atmosphere. The microstructures of 12 h-milling composite powders and sintered bulk materials were characterized by OM, XRD, SEM and EDX. The results showed that the composite powders were completely homogeneous, and fine-grained Ti/Al/Nb composite powders were made. The microstructure of the consolidated alloy was composed of fine equiaxed grains with large pure Nb particles. And the results also indicated that the compressive strength and ductility of the sintered TiAl-based bulk material at RT could be improved effectively by adding 10% Nb element. The yield strength (σ 0.2 ) and fracture strength (σ b ) of the alloy were 842 MPa and 1314 MPa, respectively, and the compressive ductility (δp) was 12.4%.

The oxidative energy storage behaviors of a designed novel system comprising a nickel hydroxide film electrode and an oxygen-reducing platinum cathode were investigated by various electrochemical techniques. The structure and morphology of samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. It is found that the oxidative energy storage in the Ni(OH) 2 electrodes can be obviously enhanced in the coupling system containing the cathode electrolytes with higher oxygen content or lower pH value. The results of the oxidation-discharge cycle tests show that the Ni(OH) 2 film electrode oxidized in the coupling system with 1.0 mol/L Na 2 SO 4 (pH=2) as cathode electrolyte for 600 s presents discharge capacities of 79.0 mC/cm 2 at the first cycle and 97.9 mC/cm 2 at the 12th cycle, suggesting the excellent reversibility of the investigated oxidative energy storage and conversion system.

The Ti-50%Al (molar fraction) composite powder was synthesized by high energy ball milling (HEBM). The characteristics of the composite particles, including surface morphology, structure and components, were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The mechanochemical reaction between Ti and Al gradually took place through intermediate stages during milling, and resulted in the formation of disordered Ti/Al phases. Dissolution of Al in Ti (after 9 h milling), nanocrystalline Ti/Al solid solution and high density of dislocations were caused by HEBM. The element distribution of the mechanically alloyed Ti-50%Al composite powder was close to the initial composition, but the distribution was inhomogeneous.

The corrosion behaviors of extrusion-drawn pure magnesium wire soaked in simulated body fluid (SBF) and 0.9% NaCl solution were studied. The corrosion law of the pure magnesium wire immersed in SBF was investigated by measuring the average corrosion rate and the pH values of the solution after corrosion. It is found that the corrosion mechanism of the pure magnesium wire was pitting after the observation of corrupted surface morphology by scanning electron microscopy (SEM). Moreover, the corrosion law of extrusion-drawing pure magnesium wire in 0.9% NaCl solution implied that the smaller the grain size of the wire is, the better the corrosion resistance exhibits.

Powder metallurgy was used to fabricate a bulk ultrafine grain size (UFG) Mg-3Al-Zn alloys. Nanocrystalline alloy powders with an average grain size of 45 nm were synthesized via ball milling of elemental powders of Mg, Al and Zn. The milled powders canned in Al containers were subjected to cold (at room temperature) or hot press (for 40 min at 633K), respectively, in a vacuum furnace. The sintered samples were extruded at 423 K to further solidify. The results show that the average grain size is 180 nm for the cold samples, and that is 600 nm for the hot samples. The cold-press alloys show a yield stress of 426 MPa. The high strength of UFG Mg is attributed to the fine grain strengthening mechanism resulting from the strong dependence of strength on the grain size for HCP metals. The consolidated samples of the cold-press and hot-press alloys have a final density of (1.777±0.006) and (1.800±0.006) g/cm 3 , respectively.

The evolution in microstructure and composition of the milled Ti-Al composite powder with different milling time were investigated. It shows that with the milling time increasing, the initial powder underwent a successive change in its morphology from a flattened shape (2 h) to a fine, equiaxed and uniform one (above 6 h). The milled Ti-Al composite powder was nanocrystalline with the average crystallite size of about 17 nm after milling for 8 h. The evolution mechanism of Ti-Al composite powder was elucidated. The Ti(Al) solid solution is formed through a gradual and progressive solution of Al into Ti lattice. By differential thermal analysis on the ignition temperature of the reaction between Ti and Al as a function of milling time, it indicates that mechanical milling of the powders significantly lowered the ignition temperature of the reaction by refining its Ti-Al composite structure.

Nanocrystallite Mg-3Al-Zn alloy was synthesized by ball milling of elemental powders of Mg, Al and Zn under hydrogen atmosphere. The powders of Mg, Al and Zn were mechanical alloying and disproportionated by ball milling under hydrogen and desorption-recombination was then performed. The structural changes due to both the milling in hydrogen and the subsequent desorption-recombination treatment were characterized by X-ray diffraction (XRD). The desorption–recombination behavior of the hydrogenation alloy was investigated by differential scanning calorimetry (DSC). The morphology and microstructure of the final alloy powders subject to desorption–recombination treatment were observed by TEM and HRTEM, respectively. The results showed that, by milling in hydrogen for 60 h, the Mg-3Al-Zn alloy was disproportionated into nano-structured with average size of about 60-70 nm, and a subsequent desorption–recombination treatment at 320°C for 30 min alloy didn’t vary the average crystallite size of powders.

In this study, a combined method based on cold extrusion and cold drawing was used to fabricate pure Mg mini-tubes. Their mechanical properties and corrosion behavior in simulated body fluid were systematically investigated. The results demonstrated the as-drawn pure Mg tube exhibited superior strengths with yield strength and ultimate tensile strength of 146.9 ± 5.3 MPa and 187.4 ± 7.4 MPa, respectively. Moreover, the as-drawn pure Mg tube also revealed relatively good corrosion resistance. After soaking in SBF for 144 h, the average corrosion rate of the pure Mg tube is 0.36 ± 0.03 mm y−1. The refined microstructure and strong basal texture induced by severe plastic deformation account for the improvement of corrosion resistance.

A B2O3-doped SnO2 thin film was prepared by a novel experimental procedure combining the electrodeposition and the hydrothermal treatment, and its structure and electrochemical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) spectroscopy and galvanostatic charge–discharge tests. It was found that the as-prepared modified SnO2 film shows a porous network structure with large specific surface area and high crystallinity. The results of electrochemical tests showed that the modified SnO2 electrode presents the largest reversible capacity of 676 mAh g−1 at the fourth cycle, close to the theoretical capacity of SnO2 (790 mAh g−1); and it still delivers a reversible Li storage capacity of 524 mAh g−1 after 50 cycles. The reasons that the modified SnO2 film electrode shows excellent electrochemical properties were also discussed. Keywords: Modified SnO2 film, Porous structure, Electrodeposition, Hydrothermal treatment, Lithium-ion batteries

The effect of Al and Zn additives on the grain size of Mg-3Ni-2MnO2 alloy was investigated. The nanostructured Mg-3Ni-2MnO2 and Mg-3Ni-2MnO2-3Al-Zn were made by ball milling process under hydrogen atmosphere. The XRD results and TEM analysis reveal that Al and Zn additives almost have no effect on the grain size of Mg-3Ni-2MnO2 alloy. The present study provides us a feasibility of producing nano-structured magnesium alloys, based on hydrogenation, disproportionation, desorption and recombination(HDDR), by adding beneficial elements to hydrogen storage materials.

Nanostructured Mg-3Ni-2MnO 2 was synthesized by ball milling elemental powders of Mg, Ni and MnO 2 in hydrogen atmosphere. The microstructures of the powder prepared at different milling time were analyzed by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and high resolution electron microscopy(HREM). The milling time is the most key parameter impacting on the grain size and the microstructure of material. With prolonging the milling time, particle size becomes smaller and smaller. But after the ball milling time reaches about 20 h, reduction of grain size becomes slowly. When the milling time is more than 50 h, nanocrystalline fully forms. When the milling time is more than 80 h, there are more amorphous phases in materials. The average particle diameter of material is about 1 μm and the grain size is 10–30 nm.

The hydriding of as-cast Mg-5.5%Zn-0.6%Zr (ZK60 Mg) (mass fraction) alloy was achieved by room-temperature reaction milling in hydrogen, with the mechanical energy serving as the driving force for the process. The hydriding progress during milling was examined by hydrogen absorption measurement, and the microstructure change was characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), respectively. The results show that, by room-temperature reaction milling in hydrogen, the as-cast ZK60 Mg alloy can be fully hydrided to form a nanocrystalline MgH2 single-phase microstructure. In particular, the average grain size of the MgH2 phase obtained by room-temperature reaction milling in hydrogen for 16.2 h is about 8–10 nm, and the average particle size of the as-milled hydrided powders is 2–3 μm.

The extrusion ratio is one of the key parameters for manufacturing the lead-glass fiber (Pb-GF) composite wire by coating extrusion. The effect of extrusion ratio on coating extrusion of Pb-GF composite wire was studied by finite element numerical simulation with the use of the DEFOEM simulation software. The simulation result shows that the higher the extrusion ratio, the higher the effective stress that the glass fiber bears during extrusion. It is also observed that the extrusion force increases with the increase of the extrusion ratio. The extrusion experiment of Pb-GF composite wire reveals that extrusion ratio is changed by changing the quantity of glass fiber and composite diameter. The rule that increasing the extrusion ratio enhances the coating speed limit suggests that the load on the glass fiber increases with increasing extrusion ratio. Both the simulation and the extrusion experiments show that the extrusion force increases with increasing extrusion ratio.

Mg -3 Ni -2 MnO 2 hydrogen storage nanocomposites added with different composition (1%~4%) carbon nanotubes (CNTs) were prepared by mechanical milling under the atmosphere of hydrogen. Different mechanical milling process parameter has been discussed in this paper. Study on hydrogen storage ability of Mg -3 Ni -2 MnO 2- nCNTs with different composition carbon nanotubes has been carried out. The result show that Mg -3 Ni -2 MnO 2- nCNTs excellent heat conductivity and good hydrogen storage (more than 6%vol) ability, the CNTs improve the mass transfer and heat transfer properties of the Mg -3 Ni -2 MnO 2, thus enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg -based namocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles enhancing the kinetic property of hydrogen absorption and desorption of the hydrogen storage nanocomposites, and raising the hydrogen storage capacity. Due to the addition of the carbon nanotubes, the milling stress in the process of preparing the Mg -based namocomposites is reduced, the components can be closely bonded easily, and the additives can play better catalytic roles.

Under the condition of equal flow, the maximum and minimum theoretical values of gap size were studied and an estimation equation was established for the clad extrusion of the brittle core cladded by plastic metal materials. The results show that the gap size is a key parameter for the continuous clad extrusion and the molding speed. Its maximum value (Hmax) is 0.24 mm and the minimum one (Hmin) is 0.12 mm. At a gap size of 0.18 mm, the maximum of metal extrusion per unit of time and the optimal coating speed can be obtained.

Interface characteristics of the deformation processed composite prepared by mutual insoluble elemental powders of Cu and Cr were investigated by SEM and HREM. The SEM results reveal that the interface between Cu and Cr phases is rough and beneficial to mechanical interlocking. The HREM results show that a significant diffusion exceeded mutual solubility between Cu and Cr exists in a range of 40 nm, and nano-crystalline microstructure of different phases is found at the interface. The formation of such interface structures is discussed and attributed to the manufacture process and different phase properties. Rather than a simple mechanical interlocking, the interface is an organic combination and can enhance the composite properties.

Bulk ultrafine-grained Mg-3Al-Zn alloy has been made of elemental powders by mechanical milling, vacuum hot pressing and warm extrusion sequentially. As the only variable, ball milling time was 20 h, 40 h, 60 h and 80 h, respectively. Microstructural studies and mechanical strength were characterized by SEM, XRD, TEM and tensile tests. At 60 h, the particle size of the milled powders decreased to 10 μm. With extension of time, the grain sizes of nanocrystalline powders were 41, 39.5, 38.5 and 38 nm. Under the same hot pressing and extrusion conditions, the grain sizes of extruded materials were 600, 565, 555 and 550 nm, respectively. The results of tensile tests showed that increasing milling time under 60 h improved the strength of the extruded alloys, however, reduced the ductility due to lower relative density and more defects. This also indicated that better ductility with high strength should be obtained if densification process was further improved. Meanwhile, the high ultimate strength of 419 MPa results from oxide dispersion strengthening and dislocation strengthening besides grain refinement strengthening.

Microwave peroxide oxidation is a less greenhouse gas emission and energy-efficient technology to destroy toxic organic compounds in hazardous waste. The research novelty is to adopt the innovative microwave peroxide oxidation in H2SO4/HNO3 solution to efficiently destroy the polychlorinated dibenzo-p-dioxins (PCDDs)/Fs in municipal solid waste incineration fly ash. The major objective of this paper is to study dynamic destruction of PCDDs/Fs using the microwave peroxide oxidation. Almost all PCDDs/Fs in the raw fly ash can be destructed in 120 min at a temperature of 423 K using the microwave peroxide oxidation treatment. It was found that the microwave peroxide oxidation provides the potential to destruct the PCDDs/Fs content in municipal solid waste incinerator (MSWI) fly ash to a low level as a function of treatment time. A useful kinetic correlation between destruction efficiency and treatment conditions is proposed on the basis of the experimental data obtained in this study. The significance of this work in terms of practical engineering applications is that the necessary minimum treatment time can be solved using a proposed graphic illustration method, by which the minimum treatment time is obtained if the desired destruction efficiency and treatment temperature are known. Because of inorganic salt dissolution, the temperature would be a critical factor facilitating the parts of fly ash dissolution. Material loss problem caused by the microwave peroxide oxidation and the effects of treatment time and temperature are also discussed in this paper.