The effect of pulsed magnetic field (PMF) on the solidified structure of H13 steel during directional solidification with various growing rates was investigated. It was found that the primary dendrite arm spacing (λ₁) and the secondary dendrite arm spacing (λ₂) both decreased under the PMF with exciting voltages in a range of 50 V-200 V. λ₁ and λ₂ decreased with the increase of exciting voltage. With the increase of magnetic field frequency, λ₁ and λ₂ firstly decreased and then increased. While with the increase of growing rate, the reduction degree of λ₁ and λ₂ decreased. The PMF causes melt convection during directional solidification, which brings hot melt in the heating zone to the solidification front, thus the temperature gradient near the solidification front increases, leading to the decrease of λ₁ and λ₂.

The microstructure and crystallographic features of X80 pipeline steel of 18.4 mm in thickness, which was prepared by ultra-fast cooling (UFC) technique, were characterized by means of optical microscope, electron scanning microscopy, and EBSD technique. The performance of the steel by drop weight tear test (DWTT) was investigated in terms of the crack propagation and the morphology of fractured surfaces, while the mechanism related with the crack arresting ability of the steel resulted from UFC treatment was revealed . The results show that the microstructure of the steel is primarily composed of AF, CB, and M/A island, and the area fractions of AF and CB are ~83%, and ~17%, respectively. The effective grain size is ~3.5 μm, and the fraction of high-angle boundary is ~40.9%. The steel with higher fractions of AF and small-sized M/A island possesses smaller effective grain size, which is beneficial to the crack arresting ability of the steel. The mechanisms related to the enhancement of the crack arresting property may be ascribed to that the UFC promots the formation of AF, and increases the amount of small-sized M/A island by increasing cooling rate. Additionally, the variant selection during bainite transformation is weakened by UFC. Thus, the effective grain size is decreased, and the density of high-angle boundary is increased.

The effect of Al- and Ce-content on the microstructure and the evolution of second phases of Mg-alloys Mg-Al-Ce were investigated, while the relevant mechanism related with the formation of intermetallic phases and the grain refinement of alloys were analyzed thermodynamically. The results show that the addition of certain amount of Ce can effectively refine the grain size of Mg-Al alloys, while with the addition of 2.5% Al and 2% Ce, the grain size could be decreased from 1000 μm for pure Mg to 280 μm for the alloy Mg-Al-Ce. According to the data fitting of experimental results the optimum content (in mass fraction) of Al and Ce were 6.4%~7% and 1.6%~2% respectively,the grain size can be reduced to 160 μm. Results of experiment and thermodynamics calculation indicated that intermetallic compounds of Al-Ce have smaller formation enthalpy than that of Mg-Ce and Mg-Al, and the phase Al₄Ce preferentially formed in the melts while the small intermetallic compounds Al₄Ce adsorbed on the α-Mg grains leading the formation of lamellar eutectic, which can hindered the growth of α-Mg grain and so as to refined the grains.

Porous TiC-ceramics of three-dimensional network structure were prepared by organic precursor impregnation method using polyurethane sponge as precursor with a small amount of powders of reduced iron, carbonyl iron and titanium as the sintering additives. The influence of the pore size of polyurethane sponge and times of slurry-applying on the porosity and skeleton diameter of porous TiC-ceramics was investigated. Then composite of Bi-continuous phase TiC/Fe was prepared by pressureless infiltration method. The phase composition, the macro- and micro-structure as well as the hardness distribution of the composite were assessed. Results show that the prepared porous TiC-ceramics is integrated in structure, while their porosity and size of TiC-skeleton are controllable. The composite of TiC/Fe exhibited a perfect bi-continuous phase structure with a good combination between TiC and Fe. A gradient hardness distribution of two-phase combining areas was observed.

A super-hydrophobic complex film was prepared on AZ91 Mg-alloy by a two-step process, i.e. first micro-arc oxidizing (MAO) and then applying blended mixture of graphene/stearic acid (G/SA). The surface wettability, morphology and chemical composition of the super-hydrophobic film were characterized by contact angle measurement, scanning electron microscope and FT-IR spectrometer. After applying the G/SA composite, the hydrophilic porous surface of MAO layer could be transformed into a super-hydrophobic one with static contact angle of 162°. In comparison with the bare Mg-alloy, the corrosion current density decreased and the electrochemical impedance increased by four orders of magnitude for the AZ91 alloy with the super-hydrophobic complex film. The high corrosion resistance can be attributed to the high insulation of the MAO film and the blocking effect of graphene.

Carbon nanotubes (CNTs) and carbon black (CB) were used as the hybrid reinforcing fillers, the coordinated effect of different fillers on the properties of composites was investigated. The filling content of CNTs increases as the decrease of CB content, and the mass ratio of CNTs increase to CB decrease is fixed to m (CNTs):m(decreasing amount of CB)=1:2.5.The dispersion of CNTs at the brittle fracture surface was gottenby the scanning electron microscopy (SEM). The flatness and height difference of the tensile fracture-surface were observed by 3D measuring laser microscope. The tensile strength was the best when 4 phr CNTs was filled, that was 11.41% higher than that of composites with 0 phr CNTs. The processability was worse and the modulus was enhanced, abrasion property increased with the increase of CNTs and composites with 8 phr CNTs was 21.14% more wearable than 0 phr CNTs. According to the loss factor of dynamic mechanical analysis (DMA), rolling resistance of composites was reductive but wet-skid resistance decreased with the increase of CNTs.

The effect of 1- ethyl -3- methyl imidazole tetrafluoroborate ([Emim]BF₄) on the nucleation and growth of PbO₂ coating on glassy carbon electrode was studied during the electrodeposition process by means of in-situ cyclic voltammetry, chronopotentiometry and chronoamperometry with an electrochemical workstation. Besides, the surface morphology and crystal structure of PbO₂ coating was characterized by SEM and XRD. The results show that PbO₂ electrodeposition process follows the three-dimensional continuous nucleation model, the addition of ionic liquid in the electrolyte does not significantly change the electrocrystallization mechanism of PbO₂, but can inhibit the nucleation and crystal growth rate of PbO₂, so as to decrease the PbO₂ grain size, densify the coating and enhance the electrochemical performance of the resulted PbO₂ electrode.

Co-W alloy coatings were prepared on Cu substrates by galvanostatic electrodeposition, which are amorphous if the concentration of WO₄^2- ≥0.075 mol/L. Electrochemical analysis showed that the amorphous Co-W alloy coatings exhibited excellent electrocatalytic activity for hydrogen evolution reaction (HER) in 1 mol/L NaOH solution. The HER occurs though a Volmer-Heyrovsky reaction pathway. The S-4 coating (W content is 40.1 mass%) showed the best HER activity and its apparent exchange current density j_o equals 3.17×10^-5 A/cm². Moreover, the cathode current density of the S-4 coating exceeds that of commercial Pt when the applied potential is more negative than -1.464V_vs.SCE. In addition, EIS results suggested that the high HER activity of the amorphous Co-W alloy coatings was mainly attributed to both of the high intrinsic catalytic activity and the large specific surface area (electrochemical active area).

The microstructure and mechanical properties of a new high strength Al-Mg-Si-Cu alloy prepared by low frequency electromagnetic casting (LFEC) alloy were studied by using optical microscope, energy dispersive spectroscopy (EDS), DSC analysis, JMat Pro 5.0 software and mechanical tests at room temperature. The results show that the temperatures of homogenization and solid solution for the alloy can be identified as 540℃ and 550℃ respectively. Mg₂Si phase could refine the as-cast grain size obviously and its effect on the as-cast grain refinement increases with the increase of Mg₂Si content in the alloy. While, the refining effect of Mg₂Si and other grain refiners on the grain sizes of ingots will be reduced by the excess of Mg or Si. However, the excess of Mg content in the alloy increases the elongation to more than 19% without reducing its strength. With the addition of 1.60% (mass fraction) Mg and 1.15% (mass fraction) Si to the Al-Mg-Si-Cu alloy exihibits higher strength (ultimate tensile strength 419 MPa and yield strength 362 MPa respectively) with undiminished ductility (elongation 18.75%).

A test rig has been built to investigate the heat capacity of emulsions of paraffin/ water as well as their stability by pumping circulation. The results show that the emulsion kept at an appropriate level of stability and heat capacity during the desired storage period. However, the stability by pumping circulation depends largely on the phase change temperature of the used paraffin. The heat capacity of the emulsion is the sum of the sensible heat capacity of water and the sensible and latent heat capacity of paraffin. In the typical temperature range of 5°C to 11°C for cold supply networks, the emulsion has a heat capacity of 56 kJ/kg, which is twice as high as that of simple water.

The microstructure and texture of β forged Ti-6246 biscuit were studied using optical microscope (OM) and electron backscattered diffraction (EBSD). It is found that a mesh-basket like microstructure with elongated β-phase grains along the metal flow direction was formed after forging the Ti-6246 biscuit in β-phase state. The β-phase presented a strong <100> fiber texture parallel to the deformation direction. The texture components of transformed α-phase are controlled by the parent β-phase, but the intensity of the transformed α-phase is influenced by variant selection. The variant selection, the α-phase colonies with a common c-axis often situated at the prior β-phase boundary when the neighboring β-phase grains share a common {110} plane, is one of the important reasons for the strengthened α-phase texture intensity.