6061 Al-alloy plates were prepared by friction stir process (FSP) with conventional air cooling and additional water cooling, and the microstructure and mechanical properties of the FSP 6061 Al-alloys were investigated. Results show that the processed zone was characterized as equiaxed uniform ultrafine-grained (UFG) microstructure with low dislocation density and high fraction of high angle grain boundaries (>70%), and the average grain size was refined to 200 nm in the condition of additional water cooling. Spherical and rod-like precipitates were observed in the FSP 6061 Al-alloy. The applying of additional water cooling suppressed the growth of precipitates, led to the solid solution of some elements in the matrix, and reduction of precipitate size and space. The FSP 6061 Al-alloy prepared with additional water cooling exhibited higher effect of grain boundary strengthening and precipitation strengthening, resulting in a high ultimate tensile strength of 505 MPa, which was 55% higher than that of the 6061 Al-alloy of peak aging state.

The microstructure and mechanical properties of a new type of low expansion superalloy GH2909 after long time exposure up to 2000 h at 550℃, 600℃ and 650℃ respectively were investigated. The results show that the alloy had a good microstructure stability and high mechanical properties, namely a slightly increase in strength and little change in plasticity, after aging at 550℃ and 600℃ for 2000 h. However, after 2000 h aging at 650℃ the mechanical properties of the alloy dropped significantly: the strength at room temperature and high temperature decreased significantly, and the plasticity decreased at room temperature, especially the reduction of area at room temperature decreased sharply, but the plasticity increased significantly at high temperature. This is mainly due to the precipitation of a large number of needle-like ε/ε″ phases that penetrate the grains and have "Widmanstatten structure"-like morphology in the microstructure of the alloy during the long-term aging process at 650℃, resulting in a significant reduction in the quantity of strengthening phase γ′ phases. At the same time, the stability of γ′ phase decreases at 650℃ and the size of γ′ phase increases significantly.

The mechanism of recrystallization and texture evolution of Mg-alloy sheet was elucidated by means of an established multi-scale calculation model. First of all, the numerical calculation of asymmetric warm-rolling process was carried out by using finite element method, and the equivalent plastic strain and strain rate were obtained as the reference boundary parameters conditions. By introducing the hardening equation based on dislocation density evolution, the coupling calculation of the viscoplastic self-consistent (VPSC) model and cellular automata (CA) model were achieved. The stress and strain, as well as the dynamic recrystallization microstructure and deformation texture on the microscopic scale were obtained. Based on this method, the influence of strain rate on dynamic recrystallization microstructure variation during asymmetric warm-rolling was calculated. The microstructure of warm-rolled AZ31 Mg-alloy sheet prepared by different cooling conditions was experimentally verified by electron back-scattered diffraction (EBSD). The simulation results show that the grain can be refined by increasing the strain rate appropriately and the experimental results show that the weakening degree of the basal texture of the alloy sheet by air cooling after rolling is higher, which is beneficial to the enhancement of the deformation ability of the Mg-alloy sheet along its thickness.

The influence of running-in process on friction characteristics of Ti-alloy by water-based lubrication process were investigated via CETR universal micro-tribometer (UMT-2) with Ti6Al4V disc and Si3N4 ball as tribo-pairs, konjac glucomannan (KGM) solutions as lubricant. The differences of the lubricating properties for Ti-alloy after dry friction and boric acid running-in process were analyzed. The results show that the wear area on the Si₃N₄ ball generated in the running-in process is the key factor that influenced the achieving of super-low friction. The super-low friction state (friction coefficient less than 0.01) could be acquired with KGM solution after both boric acid running-in and dry running-in. In the case of dry friction running-in, the super-low friction coefficient can be acquired only for the case with higher concentration KGM solutions and higher running speed, which mainly rely on the stronger hydrodynamic effect. In the case of boric acid running-in, the surface roughness of the tribo-pairs were greatly reduced, and the hydration layer of KGM was promoted by the chemical reactions between the boric acid and the KGM molecules. The super-low friction state could be achieved by the repulsive force between the hydrated KGM layers even for the solutions with low concentration of KGM.

The primary doped products of RGO/PANI were synthesized via in situ polymerization method in acetic acid with graphene (RGO) and different proportions aniline (ANI) as raw materials, and then the secondary doped products of RGO/PANI were obtained via de-doping with ammonia and afterwards re-doping with acetic acid. The structure and morphology of the prepared products were characterized by IR, UV and SEM. Their anticorrosion performance was assessed by electrochemical workstation. The results show that the primary doped products with the mass ratio 1:10 of RGO to ANI had the best morphology and anti-corrosion property. The polyaniline grown on the surface of graphene is about 300~650 nm in length and 70~100 nm in diameter, and the corrosion inhibition efficiency was up to 73.19%. The products obtained by secondary doping of acetic acid had better morphology, higher corrosion inhibition efficiency and excellent corrosion resistance performance. The corrosion inhibition efficiency is up to 80.21%.

In order to improve the photocatalytic activity and efficiency of ceria materials, the binary composite photocatalyst with a core/shell structure was fabricated by grafting CeO₂ nanoparticles on the surfaces of worm-like mesoporous silica supports. The prepared composite was characterized by means ofXRD, SEM, TEM, STEM-EDX mapping, UV-Vis, Raman, PL, N₂ adsorption-desorption measurements. The photodegradation towards methylene blue catalyzed by composite particles was tracked under UV irradiation. The results show that the particle size of mesoporous silica with a specific area up to 1627 m²/g is in the range of 180~200 nm, which was covered with an uniform layer of ca. 20 nm in thickness composed of a large number of nanometer ceria particles. The mesoporous cores exhibited a strong adsorption capacity for MB and therefore enriched MB around CeO₂ active nanoparticles, resulting in enhanced photodegradation activity for MB. Furthermore, it is worth noting that CeO₂ nanoparticles in the shell were doped with Er³⁺ and then calcinated in nitrogen atmosphere, can further enhance the photodegradation reaction activity of the binary composite photocatalyst.

High temperature low cycle fatigue performance of the ultra-supercritical steam turbine rotor steel 10%Cr was studied by controlling the strain and temperature, as well as the characterization of surface morphology and sub-grain structure with SEM and TEM for the steel before and after test. Based on the experimental data the Ramberg-Osgood parameters and Manson-Coffin parameters of the high temperature and low cycle fatigue characteristics of the material were obtained through fitting the stress-strain curves, stress-life curves and strain-life curves. The hysteresis loops and stress-life curves in the initial and final phases of the high temperature low cycle fatigue experiment were analyzed comparatively in terms of the relation between plastic strains with temperature and strain amplitude. Results show that the plastic strain of steel 10%Cr is much obvious under high temperature conditions, and the fatigue life of the material decreases with the increasing strain amplitude. The plastic strain rate experienced three stages with the fatigue cycle, namely the falling stage-the transition stage-the rising stage, and the plastic strain rate has an inflection point with the variation of fatigue cycles. The maximum crack length varied nonlinearly with the number of cycles, and as a result of the high temperature and low cycle fatigue process, the size of sub-grains of the steel increases.

The 18.5% Cr low nickel type duplex stainless steel with high manganese content was compressed by using thermal simulation test machine with large deformation of 70% under deformation conditions of 1123~1423 K/0.01~0.1 s^-1, while the microbstructure characteristics and softening mechanism of two phases during thermal deformation were investigated. The results show that the thermal compression softening in the range of 0.01~0.1 s^-1/1123~1223 K was dominated by recrystallization of ferrite phase, while in the range of 0.1 s^-1/1323~1423 K and 10 s^-1/1223 K was dominated by recrystallization of austinite phase. When deformed at 1223 K and 0.01~10 s^-1, the dislocation tangles in the ferrite phase evolved into dislocation cells and the dislocation lines appeared with the increase of strain rate, and the substructure of austenite phase transformed into fine recrystallized grains. When deformed at 0.1 s^-1 and 1123~1323 K the substructure of the dislocation cells gradually formed due to the increase of dislocation density in ferrite phase with increasing deformation temperature, but the deformation microstructure in austenite phase changed from DRV to DRX with the decrease of dislocation density. The deformation apparent activation energy Q and the apparent stress exponent n were calculated as 514.29 kJ/mol and 7.13 respectively based on thermal deformation equation, and the constitutive equation with Z parameter was established. Meanwhile, the critical conditions of DRX have been obtained by the relationship between work hardening rate and flow stress, and the relationships between Z parameter and the critical conditions were also determined. The hot working map analysis shows that the instability zone gradually decreases with increasing deformation strain, and the optimal processing zones are within the range of 1348~1432 K/1~10 s^-1, and corresponding values of power dissipation coefficient are above 0.4.

The difference of oxygen acting mechanisms between the as-deposited and as-annealed In₂O₃ films under the oxygen-controlled conditions was investigated by the microstructure as well as optical and electrical properties. Both kinds of oxygen-controlled behaviors could effectively improve lattice order and reduce oxygen vacancies in In₂O₃ films, which narrowed optical band gap, decreased carrier concentration and increased mobility. Oxygen with a high activity was injected into films in a non-equilibrium manner during plasma-deposited process, and oxygen with a low activity by the equilibrium way accessed in films during annealing process. As a result, under different oxygen acting mechanism, the as-annealed In₂O₃ film had less structural defects and more oxygen vacancies than that of the as-deposited film by plasma sputtering, and in turn, had better light-transmittance and electrical conductance. Finally, oxygen-controlled behavior in indium oxide film underlies optical and electrical characteristics.