This report investigates the effect of firing temperatures on the phase formation, microstructure, electrical, and energy storage properties of lead-free Sr0.3(Bi0.7Na0.67Li0.03)0.5TiO3 (SBNLT) ceramics, synthesised by combustion technique. The samples were calcined between 700°C and 900°C for 2 h and sintered between 1100°C and 1200°C for 2 h. The ceramics exhibited coexisting rhombohedral and tetragonal phases, which were confirmed by the Rietveld refinement technique. A morphotropic phase boundary (MPB) of the rhombohedral and tetragonal phases, with a ratio of 49:51, was obtained at the sintering temperature of 1175°C. The highest maximum dielectric constant (εmax = 4667), polarisation (Pmax = 28.80 µC/cm2) and energy density (W = 0.95 J/cm3), with a breakdown strength of 70 kV/cm, were achieved from the sample sintered at 1175°C.

ABSTRACTThis study employed metronidazole skeletons based on the target branched molecules (TBMs) for achieving efficient anti-corrosion of mild steel in HCl solution. In contrast, the reference linear molecules (RLMs) carrying a single metronidazole framework were also made. The excellent corrosion resistance performance of the target dendrimers for mild steel electrodes in HCl solution was demonstrated. It is shown that the TBMs displayed a superior anti-corrosion effect for mild steel over RLMs in HCl medium at 298 K (at 0.15 mol/L, TBM1, 97.70% versus RLM1, 90.89%). It is shown that the standard Gibbs free energy changes of the adsorption of the TBMs on mild steel surface are below −33 kJ/mol (TBM1, −34.58 kJ/mol), thus an enhanced adsorption film was formed.

The synergetic effect of strontium (Sr) and rare earth elements (RE) on the corrosion properties of as-cast Mg–9Al–1Zn alloy were studied. Via the addition of 0.5 wt-% RE and 0.5 wt-% Sr (RE/Sr ratio of 1), a remarkable reduction in the corrosion rate of AZ91 was observed. The reason was found to be related to the decrement of the micro-galvanic corrosion by the modification of the β-Mg17Al12 phase (changing its morphology from semi-continuous to a more spheroid shape) and formation of proper amounts of Al11RE3 and Al4Sr intermetallics. However, the excess RE/Sr ratio impaired the corrosion resistance, which can be related to the micro-galvanic effect by excess amounts of Al11RE3 and Al4Sr intermetallics.

Phase transformation, microstructure evolution, and mechanical properties of Ti–3Al–5Mo–4Cr–2Zr–1Fe alloy were investigated during a continuous heating process. Three microstructures, specifically lath, duplex, and lamellar structures, were examined. The activation energies for phase transition in these structures were measured as 277, 220, and 193 kJ mol−1, respectively. The phase transition follows: For the lath structure, β transforms into αacicular (550–660°C), αacicular converts to β (660–785°C), αlath does to β (660–850°C); For the duplex structure, β transforms into αacicular (545–660°C), αacicular converts to β (660–770°C), αlath does to β (660–850°C); For the lamellar structure, β transforms into αsecondary (560–615°C), αsecondary converts to β (615–705°C), αlamellar dose to β (615–850°C). The lath and duplex structures exhibited favorable comprehensive properties compared to lamellar microstructure.

An alternative battery system to the lithium-ion battery has become paramount due to its high cost and limited distribution across the earth's surface. One of the significant challenges encountered by Na+ batteries is the development of efficient anode material. ZIFs have been considered as one of the potential electrode materials for Na+ batteries. ZIF is a sub-family of the metal–organic framework. Aside from the fact that they are utilised for sodium-ion batteries, their exceptional thermal stabilitiy, porous structure, and robust functionalities make them suitable for various applications. In this review, the working principles of Na+ battery, the synthesis procedure of ZIF carbon materials, electrochemical performances of each material or composite, performance enhancement strategy and morphology were explored and summarised.

Carbon-based capsule nanomaterials were synthesised through gas-phase detonation using acetylene gas, oxygen, and pentacarbonyl iron. The resulting nanoparticles consisted of a thin layer of capsule-like amorphous carbon with a high specific surface area and strong adsorption capacity. The products exhibited good electromagnetic properties with good reflection loss and absorption capabilities in the frequency range 2–18 GHz. The effective response frequency band ranged from 10.12 to 11.30 GHz, and the reflection loss reached 10.94 dB at 10.96 GHz. The absorption mechanism was mainly owing to dielectric loss as no significant magnetic loss was observed. These nanomaterials have the potential to be used as a matrix for carrying other nanomaterials and for adjusting the impedance-matching of composite materials, thereby enhancing electromagnetic-wave absorption.

The microstructure, mechanical properties and degradation behaviour of Mg95Y3Zn2 (MYZ), Mg95Y3Zn1Cu1 (MYZC), and Mg95Y3Cu2 (MYC) (at.-%) alloys have been studied. All the alloys mainly contain α-Mg matrix and LPSO phase. By substituting Zn for Cu, the composition of the LPSO phase transformed from Mg–Y–Zn to Mg–Y–Zn–Cu, and then to Mg–Y–Cu. The ultimate compressive strength is 227, 231 and 238 MPa, respectively. The MYC alloy exhibited much higher degradation rate than MYZC and MYZ alloys. The strong galvanic coupling effect between LPSO phase and the matrix, the grain size refinement and the weak protection from the corrosion product layer are responsible for the high degradation rate. It is suggested that the newly developed MYC alloy is promising for fracturing ball application.

NiO films were deposited on glass and Si(100) substrates by reactive pulsed laser deposition from the Ni target. Nd: YAG laser (1064 nm) was used. The oxygen pressure was between 0.05 and 0.3 Torr. The optimum conditions for a good-quality NiO film are an oxygen pressure of 0.1 Torr and a laser power of 410 mW. Preferred orientation changes from (200) to (220) and D decreases from 27 to ∼9 nm as the temperature increases from 200 to 300°C. The preferred orientation changes into (111), nanoparticles size reduces from 46 to 26 nm and D drops from 27 to 10 nm as laser power increases from 410 to 820 mW. The oxygen pressure is significantly affecting the composition and morphologies of the NiO films. The optical band gap was 3.35 eV.

The microstructure and tensile properties were studied in a low-alloy steel plate treated under ultra-fast heating, quenching, and tempering. The microstructure after heat-treatments was predominantly martensite, with low fraction of bainite and ferrite. The tensile tests showed a 100 MPa improvement in strength and a doubling of the total elongation with the increase in heating rate. The tempering process considerably enhanced the ductility from 1–4% to up to 14% in the samples treated at fast heating rates..Furthermore, the work hardening capacity of ultra-fast heated steel was superior compared to steel treated under conventional quenching and tempering. The results suggest that the tempering stage after ultra-fast heat-treatments and quenching further improves the properties compared to the standard quenched and tempered condition.

Today, the increasing growth of industrial activities has caused the entry of large amounts of pollutants into water resources. Owing to the toxicity of these pollutants, their removal from water sources is essential. An adsorbent based on microcrystalline cellulose/graphene oxide (MCC/GO) aerogel was synthesised and its efficiency was investigated to remove methylene blue (MB) dye from aqueous solutions. Various factors such as concentration of GO in microcrystalline cellulose/graphene oxide (MCC/GO-x) aerogel, pH solution, adsorbent dosage, initial concentration of MB and contacting time were optimised on the adsorption capacity. The outcomes displayed that the maximum adsorption capacity could get to 645 mg g−1. The batch adsorption tests confirmed the pseudo-second-order and Langmuir isotherms as the best-fitted models to describe the adsorption of the adsorbent.

The pulsed magnetic field melt treatment (PMMT) was applied in the direct chill (DC) casting of 6061 alloy billets with a diameter of 430 mm. The results indicated that the billet solidification structure was refined and homogenised. The grain size was reduced by 20.4% in the billet centre. Meanwhile, the PMMT can reduce the addition of grain refiner. The negative macrosegregation in the billet centre was reduced significantly. This can be attributed to the melt structure being changed by the energy of the pulsed magnetic field, which leads to the temperature of the melt variation and increased nucleation rate. This study may offer a promising method for the high-quality large-sized 6061 alloy billets preparation with less grain refiner.

The effects of the non-basal slip and twinning modes on the mechanical behaviour and texture evolution of as-extruded AZ31 alloys during uniaxial compression at room temperature have been investigated by experiments and Visco-Plastic Self Consistent (VPSC) modelling. The results show that the activation of pyramidal slip and {10-11} contraction twinning (CT) can reduce the strain hardening rate in the later stage of compression. And the prismatic slip has a significant effect on the strain hardening rate, the activation of {10-12} extension twinning (ET) can significantly reduce the strain hardening rate and the compressive yield strength. Increased activity of the {10-11} CT causes the pole density transfer to the normal direction (ND) in the {0002} pole figure.

To produce bearings with more reasonable hardness profiles, a finite element model was established to simulate different heat treatment processes. Based on the simulated hardness profiles, an artificial neural network model was established to fit the relationship between the heat treatment process parameters and the hardness profiles. Genetic algorithm was used to optimise the hardness profiles and the confirmation test was conducted. The results showed that the optimised hardness profile was closer to the optimisation target. The mean absolute error of hardness was reduced by 68.16% and the root mean square error was reduced by 66.72% after optimisation. This method can be used for hardness profile optimisation and provides a reference for the optimisation of the bearing heat treatment process.

The effect of interaction between Ce and P on the microstructure and properties of copper has been rarely reported. In this study, it was investigated by utilising the OM, EPMA, SEM and TEM techniques, combined with conductivity and tensile tests. The results indicated that the grain size and conductivity of as-cast copper could be significantly influenced by the interaction. More importantly, the plasticity of as-cast copper did not seriously damage by the interaction, and the elongation of as-cast 3# (Cu-0.016P-0.075Ce) was still up to 39.3%. This is due to a strong binding force of the coherent interface between CeP and copper.

In this research, aluminium composites were fabricated using two alternative casting methods namely, traditional stir casting and ultrasonic-aided stir casting technique. The aluminium composites were manufactured by reinforcing them with three different concentrations of waste spent catalyst and silicon carbide (0.5, 1.0, and 1.5 wt-%), respectively. The microstructural and mechanical behaviour of aluminium composites synthesised using both methods were studied and compared. The microstructure of the aluminium composite obtained by the stir casting technique with ultrasonic treatment resulted in a homogeneous dispersion of reinforcement particles and grain size refinement. Moreover, the overall test results showed that the ultrasonic-aided stir-casting technique improves the microstructure and mechanical behaviour of the composites when compared to the traditional stir-casting approach.

The present paper examines the mechanisms for simultaneous manipulation of grain size and γ′ dissolution leading to the microstructure that balance creep and fatigue properties in UDIMET 720Li. For sub (near) solvus heat treatments, grain growth and γ′ dissolution occur simultaneously. Grain size following heat treatment is determined largely by the primary γ′ particle dispersion, via Zener-Smith pinning. Remarkably, grain growth occurs only as a result of precipitate dissolution. The resulting grain size is dictated by a combination of initial particle dispersion in the as-received material and heat treatment temperature. It is likely to hold so long as the initial grain size is close to the Zener-Smith limit and where the kinetics of grain growth and dissolution share similar rates.

A CuTeCrY alloy prepared by homogenising annealing, hot extrusion, solution treatment, cold drawing, and a heat ageing treatment has tensile strength and electrical conductivity of 430 MPa and 78.9% IACS, respectively. Electron microscopy analyses show that a metastable CrCu2Te phase in the solid solution alloy is eliminated by the ageing treatment, and a 3–5 nm granular bcc-Cr phase becomes distributed in the matrix. This nanometre Cr second phase is the main contributor to the strengthening of the alloy whereas the second-phase strengthening effects of micrometre Cr and Te phases are weak.

A systematic investigation on microstructural and crystallographic characteristics of martensite micro-variants in Ni54Mn25Ga20.9Dy0.1 ferromagnetic shape memory alloy was performed. The alloys exhibited a dual-phase microstructure consisting of self-accommodated tetragonal martensite and hexagonal Dy-rich dispersive precipitates. In each colony, four distinct micro-variants with different crystallographic-orientations existed, where the adjacent variant pairs connected by crossing-interfaces possessed a non-twinned relationship and other pairs connected by extending-interfaces were twin-related to each other. The corresponding twinning planes and directions were {112} and 〈111〉, respectively. Nevertheless, the twinning relationships of these twin-related micro-variant pairs were not perfect, which contained a small rotation. Interface analysis demonstrated that these two types of interface planes coincide with the orientation relationship planes and twinning planes of their connecting micro-variants, respectively.

In this paper, three-dimensional carbon superstructures (CSSs) have been proposed through an effective method. Specifically, the hierarchical self-assembly of polyimide (PI) is followed by thermal annealing. Moreover, the structural evolution of PI under the various pyrolysis time was also comprehensively studied. It is noted that the as-prepared CSSs as anode composites for LIBs, especially CSS-5 h, exhibited extraordinary electrochemical properties, exhibiting a high reversible performance, great rate performance, and excellent cycling stability. As expected, the superior electrochemical capability can be ascribed to the synergistic effect of combining the nanoflower-like carbon superstructures with nitrogen contents. Such a method might encourage the inspirations to devise and obtain various heteroatom-modulated and hierarchical polymer-derived carbon composites for LIBs.

Friction stir lap welding experiments between 6061 aluminum alloy and DP590 dual-phase steel plates were carried out. The effects of welding parameters and the addition of Cu foil interlayers with 0–0.3 mm thickness on the microstructures and mechanical properties of the lap joints were investigated. The shear strength of the joint reached the maximum value of 5337 N and showed a mixed ductile-brittle fracture mode when the welding speed, the rotating speed, and the thickness of the Cu foil intermediate layer were set to 80 mm/min, 900 rpm, and 0.1 mm, respectively. The plastic Al2Cu and AlCu intermetallic compounds formed through Al and Cu reaction at the aluminium alloy/steel interface play a beneficial role in the Cu-added joint strength.