Hot ductility, stress-strain behavior and high temperature tensile fracture behavior of wrought 316LN stainless steel were investigated. Hot tensile tests were carried out on a Gleeble 1500D thermal simulator system at a strain rate of 0.5 s^-1 over the temperature range 650-1300℃. The percentage reduction of area (RA) decreased with the increasing deformation temperature over the range of 650-850℃, and then starting from 850℃, it began to increase dramatically with values over 85% above 1000℃. When the deformation temperature comes to 1300℃, RA decreased sharply as a result of the grain coarsening due to over-heating. With the help of optical microscopy, dynamic recrystallization (DRX) was observed for the steel deformed at temperature over 1000℃. The enhancement of ductility induced by DRX was considered to play an important role in inhibition of the crack propagation. The high temperature tensile failure process of 316LN includes the nucleation, growth, and aggregation of microscopic cavities. The SEM/EDS results show that the sulfide and alumina at grain boundaries may be responsible to the formation process of cracks.

Ni-Co-Al high temperature alloys with different Co content were prepared by powder metallurgy (mechanical alloying and hot-press sintering), of which the high temperature tribological properties were investigated at 800℃. The results showed that the hardness and compressive strength, as well as the tribological properties of alloys could be improved with a Co addition in a range from 5-30 mass%, among which 20 mass% is the optimal. The observation of worn surfaces by SEM, XPS and EDS revealed that a “glaze-like film” consisted of CoO and other oxides existed on the worn surface. The high temperature tribological properties of the alloys are highly related with the composition and the spallation tendency of the formed glaze film during the friction and wear process.

The influence of friction pressure and time on morphological characteristics and mechanical property of the continuous drive friction welded joints of medium carbon steel 45(GB) was investigated in terms of the newly proposed two character factors, i.e. sticky length to diameter ratio α = length of welded zone / original diameter and scaling factor η = width of outer heat affected zone / width of center heat affected zone. The results show that, with the increase of friction pressure the sticky length to diameter ratio α increases firstly and then decreases, while the scaling factor η increases all along. However, by a friction pressure 60 MPa, the sticky length to diameter ratio α increases and the scaling factor η decreases continuously with the increasing friction time. When the integrative factor δ (δ=η/α) falls in a range 1.15-1.31, the mechanical property of joints is good because the heat input is moderate, which therefore can be used as a criterion of selection of welding parameters for gaining good performance of the continuous drive friction welded joints of the steel 45(GB).

Heterostructured nano-composite Bi₄Ti₃O₁₂/TiO₂ was synthesized by a two step process, i.e. the nano-rods TiO₂ were prepared by electrospinning technique and then the nano Bi₄Ti₃O₁₂ was grew on the nano-rods TiO₂ by a hydrothermal process. Scanning and transmission electron microscopy observation proves that the as-synthesized nano-composite is consisted of nano-rods TiO₂ decorated with nanostructured Bi₄Ti₃O₁₂. In comparison with the nano-rods TiO₂, a slight red-shift on the UV-Vis absorption spectra and a decrease of the emission peak intensity on the photoluminescence spectra could be observed for the as-synthesized nano-composite. The heterostructured nano-composite Bi₄Ti₃O₁₂/TiO₂ exhibited stronger photocatalytic activity in the decomposition of MO under visible light rather than the blank nano-rods TiO₂. The photocatalytic performance would be further enhanced with the increase of the content of the heterostructured nano-composite Bi₄Ti₃O₁₂/TiO₂ in the synthesized product.

The monodispersed polystyrene (PS) particles with the size of 200-500 nm were prepared via a soap-free emulsion polymerization method. The as-synthesized PS microspheres were immobilized on a rigid substrate surface through the attraction between the negative-charged silica and the positive-charged PS. The mechanical properties of the as-synthesized PS microspheres were measured by a Peak Force tapping atomic force microscope. The compressive Young’s moduli (E) of 2-3 GPa (Hertz’s model) and 2-6 GPa (Sneddon’s model) were calculated by the analysis of the force-displacement curves captured on the top of the PS particles. The moduli were slightly less than that of PS bulk materials, and the E values increased slowly with an increase of the size of the PS particles. In addition, the Hertz’s model might be more suitable to calculate the E of the obtained samples than the Sneddon’s model.

Thin films of magnetic alloy Co-15% W (atomic fraction) were deposited by DC magnetron sputtering on buffer layers of alloys Ru - x% Cr (atomic fraction, x=0, 20, 40) at 300℃, which were pre-deposited on a substrate of MgO(111) by the same process. The crystallographic structure of the films was examined by X-ray diffraction in terms of the epitaxial relationship between Co-W and Ru-Cr, the lattice parameters, the mosaic spread, the volume ratio of face centered cubic phase to hexagonal close-packed phase and the stacking fault densities. It was found that the lattice constant ratio c/a of hcp Co-W reduced with increasing Cr content x of Ru-Cr films due to the reduction of lattice misfit between Co-W magnetic films and Ru-Cr buffer layers. A clear correlation between the crystallographic structure and the magnetic anisotropy energy (MAE) of Co-W was confirmed, that is, the MAE was significantly enhanced with the reduction of c/a.

A Ti containing conversion film on hot-dip galvanized steel was prepared by chemical conversion in titanium sulfate solution. The surface morphology, chemical composition and ingredients of the film were characterized by means of SEM, EDS and XPS. Then the corrosion resistance of the galvanized steel coated with Ti containing conversion film was examined by NSS test, electrochemical polarization and electrochemical impedance spectroscopy (EIS). The results show that the Ti containing conversion film gradually thickens and the Ti content of the film increases with the increasing time in the solution; the film mainly consists of Ti(OH)₄/TiO₂ and Zn(OH)₂/ZnO. In comparison with the blank galvanized steel, the corrosion current density decreases, the polarization resistance and the electrochemical impedance increase significantly for the galvanized steel with Ti containing conversion film on top. The Ti containing conversion films enhance the corrosion resistance significantly, among them a film prepared in the solution for 10 min exhibits the highest corrosion resistance.

The effect of heat treatment on the microstructure of the interfacial diffusion layer of Cu/Al composite laminate prepared by cold rolling was investigated by means of SEM, TEM and micro-XRD The results show that an interfacial diffusion layer may form soon after heat treatment at high temperature; then as the heating time lengthened, the interfacial diffusion layer growths gradually from the original single-layer to become a three-layed one, while the heating time further lengthened, the morphology of the interfacial diffusion layer kept more or less unchanged besides a slight thickening; the interfacial diffusion layer consists of a layer of Al-Cu solid solution with intermetallic compound q(Al₂Cu) nearby the Al side, a layer of h₂(AlCu) in the middle and a layer of Cu-Al solid solution with intermetallic compound g₂(Al₄Cu₉) nearby the Cu side.

The main objective of the present research aims at investigating effects of the cyclic number, temperature and strain amplitude on the tension-compression asymmetry behavior of single crystal (SX) superalloy DD10. Fully reversed LCF tests with R_ε=-1 are conducted at 760℃ and 980℃ under various strain ranges, and some tests are interrupted after the 1st cycle and at the cyclic stress saturation stage to figure out the evolution of the tension-compression asymmetry and the dislocation configurations. Results show that this asymmetry behavior is affected by several factors, such as the stress field in matrix, temperature and the strain range, and these factors depict various effects in different parts of the LCF process. In the 1st cycle, the K value (the ratio of s_t to s_c) is slightly above 1 in low strain range for both temperatures, due to the compress in matrix resulted from the negative lattice mismatch. With the increment of strain amplitude or cyclic number, the tension-compression asymmetry gets much severer: at 760℃ the K is above 1, whereas at 980℃ K is below 1. TEM observations reveal that this distinct asymmetry behavior arises mainly from the different motion modes of dislocations in γ′ phase, e.g. perfect dislocations at 760℃ and stacking fault at 980°C.

The effect of natural and artificial aging treatment on tensile properties and corrosion resistance and on the microstructure and texture was investigated respectively by means of mechanical test and of observation with OM, SEM and TEM etc for aluminum alloy 7N01 plates extruded with different extrusion ratio (λ=36 and16). The results show that after natural and artificial aging there exist significant difference in the microstructure and mechanical property for the above mentioned 7N01 plates. There exist a large number of tiny recrystallized grains in the plate with higher-extrusion ratio, while coarse subgrain structures in the plate with lower-extrusion ratio; the former one possesses higher tensile strength and yield strength rather that the later one; while the precipitates at grain boundaries in the former one seemed much discrete with each other. Meanwhile, for the plates extruded with the same extrusion ratio both the tensile strength and elongation were decreased after artificial aging in comparison to those naturally aged, i.e. tensile strength was about 5.8% lower, however the yield strength increased reversely by about 25%; the precipitates at boundaries seemed also much discrete with each other after artificial aging, and thereby exhibited better corrosion resistance.

The effect of annealing temperature and time on the microstructure, distribution of silicon, texture and magnetism of the high silicon steel prepared by electrodeposition was investigated. The results showed that after annealing at 1000℃ for 210 min, the mean grain size of steel was about 190 μm with a uniform grain size distribution, and the silicon is also uniformly distributed on the entire cross section with an average Si concentration 6.3715% (close to 6.5%); With the increasing annealing time at high temperature, the texture with double crystal planes {100} and {110} preferential oriented microstructure was enhanced, and the iron loss was lowered, implying a relatively good magnetism for the high silicon steel prepared by the proposed process.

Azido-carbon nanotube (ACNT) was prepared by the reaction of azide group with carbon nanotube (CNT). The azidation of CNT was proved by FTIR, XPS and so on. Under the effect of ultrasonic wave, ACNT was uniformly dispersed into monomers of polytriazole (PTA), and then PTA/ACNT composites were prepared via in situ polymerization. The dispersion status of ACNT in the matrix resin and the microstructure of PTA/ACNT composites were observed by TEM. The influence of ACNT addition on glass transition temperature (T_g), thermostability parameter (T_d5) and thermal conductivity (λ) of PTA/ACNT composites were also examined. The results showed that in comparison with the blank PTA resin, T_g increased 33℃, T_d5 increased 15℃ in nitrogen atmosphere and 8℃ in air for the PTA/ACNT composite with 1.0% ACNT; while λ increased by 45% at 30℃ and 30% at 150℃ for the PTA/ACNT composite with 5.0% ACNT.