The hot compression deformation behavior of Ti-62A alloy was investigated via Gleeble-3800 thermal simulator by strain rate of 0.001~10 s^-1 at 800~950℃. The results show that the dynamic softening rate of Ti-62A alloy decreased with the increase of deformation temperature. This phenomenon existed in the thermal processing of other biphasic titanium alloy, α-titanium alloy and β-titanium alloy. According to the thermodynamic calculation results by Jmatpro software, the phenomenon of (α+β) biphasic titanium alloy is closely related to the decrease of the atomic activity of the main alloy elements Mo, Cr and other β stable elements with the increase of temperature and the increase of β phase ratio. The reason for the decrease of dynamic softening rate of α-titanium alloy and β-titanium alloy is more closely related to the increase of the β phase ratio with the increase of processing temperature. When the temperature rose from 800℃ to 950℃, the proportion of β phase in Ti-62A alloy increased from 32.1% to 84.3%, and the activity of Mo and Cr decreased by 64%, which thereby results in the decrease of grain boundary migration rate and dynamic softening rate of Ti-62A alloy. The true stress-strain curve at 950℃ is mostly a typical dynamic recovery type. The content of α phase decreases with the increase of deformation temperature, and the β grain size is relatively large at higher deformation temperature. The Arrhenius deformation resistance model of Ti-62A alloy was constructed based on strain compensation, with which the rheological stress behavior of Ti-62A alloy can be predicted well, correspondingly, the correlation coefficient R is 0.990, and the average relative error between the predicted value and the measured value is 8.983%.

The macro grain size distribution and microstructure change of the slab of Lean duplex stainless steel 2101 was investigated. It was concluded that columnar equiaxed crystal transformation (CET) occurred in the location, where is at the end of section No.2 of the secondary cooling zone with 25 mm from the slab surface. Decreasing the slab surface cooling strength in this zone will reduce internal temperature gradient in the shell, and promote CET transition, improve the rate of equiaxial crystal and expand the equiaxial zone at the corner. The results of microstructure analysis show that behind the section No. 6 in secondary cooling zone the morphology of austenite formed in the core of the billet can be adjusted by increasing the cooling intensity, which is also beneficial to the refinement of austenite morphology in the grain and at the grain boundary. Size of the acicular austenite structure at the grain boundary can be reduced, so as to improve the heat deformation ability of the billet.

Four kinds of ultrafine grained (UFG) pure titanium were obtained by two-pass equal channel angular pressing (ECAP) at room temperature, ECAP+rotary swaging (RS) and ECAP+RS followed by annealing at 300℃ and 400℃ for 1 h, respectively. The fatigue crack growth tests of different UFG pure titanium were carried out, while their microstructure, the fatigue fracture morphology and the crack growth behavior were investigated by TEM and SEM. Results show that the microstructure has a significant effect on the threshold of fatigue crack growth rate and the near threshold zone of UFG pure titanium. The threshold values of fatigue crack growth rate for UFG pure titanium increase with the increase of strain, and decrease with the increase of annealing temperature after RS. The turning point occurs in the fatigue crack growth rate curve, which is affected by grain size and strength of UFG pure titanium. Before the turning point, UFG pure titanium produced by ECAP+RS has stronger resistance to fatigue crack growth than that produced only by ECAP, and the resistance to fatigue crack growth of UFG pure titanium after ECAP+RS decreases with the increase of annealing temperature. After the turning point, the fatigue crack growth rates of four kinds of UFG pure titanium are slightly different and the opposite result is presented. The threshold value before the turning point and the growth rate of the near threshold zone may play much important role in enhancing the resistance to the crack growth because the growth life of the crack of the near threshold zone before the turning point accounts for a very large part of the fatigue crack growth life.

The effect of Bi on the microstructure and mechanical properties of Mg-3Al-3Nd alloy was investigated by scanning electron microscope (SEM), optical microscope (OM), X-ray diffraction (XRD) and tensile test. The results show that the addition of Bi can refine the microstructure of Mg-3Al-3Nd alloy. When the content (mass fraction) of Bi is 1% the grain size of Mg-3Al-3Nd alloy is the smallest, whilst the grain size reduced from 1854±58 μm for the plain Mg-3Al-3Nd alloy to 890±64 μm for the alloy with 1% Bi addition. The Mg-3Al-3Nd alloy is mainly composed of Al₁₁Nd₃ phase distributed at grain boundaries and granular Al₂Nd distributed within grains. With the increasing Bi content, the volume fraction of Al₁₁Nd₃ phase and Al₂Nd phase decrease, and the volume fraction of BiNd phase distributed within grains increases. The mechanical properties of Mg-3Al-3Nd alloy at room temperature and high temperature are significantly improved with addition of Bi. The ultimate tensile strength and elongation at break of Mg-3Al-3Nd alloy with 1% Bi addition at room temperature and high temperature is 167±2.3 MPa and 16.1±0.3%, 136±1.7 MPa and 19.3±0.3%, respectively.

Corrosion behavior of Q345qNH weathering steel and Q345q ordinary bridge steel in a mixed medium of simulated industrial environment solution and deicing salt was investigated by means of wet/dry cyclic accelerated corrosion test, The corrosion kinetics curves of the two steels were studied by weight loss method, and the phase, morphological structure and electrochemical characteristics of the rust layer after corrosion of the two steels for different times were analyzed using XRD, SEM and electrochemical workstation. The results show that the corrosion weight loss of Q345qNH weathering steel is slightly higher than that of Q345q bridge steel before 100 h. However, after 100 h the corrosion mass loss of bridge steel is obviously larger than that of weathering steel. The corrosion products were composed of α-FeOOH, β-FeOOH, γ-FeOOH, Fe₂O₃, Fe₃O₄ and FeOCl, but the content of unstable β-FeOOH and FeOCl on Q345q bridge steel was significantly higher than that on Q345qNH weathering steel, thereby, the rust scale on Q345q bridge steel presented lower stability; the free-corrosion potential of the rust layer on the two steels increased with the increasing time, and the free-corrosion potential of Q345qNH weathering steel increased faster than that of Q345q bridge steel, while, their free-corrosion current density showed undulatory attenuation. The protectiveness of the rust layer of weathering steel was better than that of ordinary bridge steel in the later stage of corrosion; the corrosion behavior of the two steels in the mixed medium was affected by the coupling effect of various ions. Due to the existence of unstable corrosion products such as β-FeOOH and FeOCl, the compactness of the rust layer reduced, even so, which still maintained protectiveness to certain extent. In general, the corrosion resistance of Q345qNH weathering bridge steel in the mixed media was better than that of Q345q ordinary bridge steel.

The corrosion behavior of a new developed 3Cr2Al steel in a simulated high-temperature and high-pressure oilfield formation water was studied by means of weight loss method and electrochemical technique, as well as scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) etc. Results show that compared with the plain 3Cr steel, the corrosion rate of 3Cr2Al steel decreases significantly. By short period (about 20 h) test and long period (about 144 h) test, the corrosion rate for 3Cr2Al decreases about 15% and 69%, respectively. The addition of a small amount of Al could improve the CO₂ corrosion resistance of the 3Cr2Al steel to certain extent. This is mainly due to the fact that not only the Cr-, but also the Al-enrichment did emerge in the corrosion product on the steel surface, which thereby improves the protectiveness of the corrosion product scale. In the solution with lower Cl^- concentration, the Al/Fe atomic ratio in the corrosion product is much higher than the Cr/Fe atomic ratio, namely, the enrichment of Al is more obvious. If the Cl^- concentration in the solution increases, the Al/Fe atomic ratio in the corrosion product scale decreased significantly, the enrichment of Al is weakened, correspondingly, the semi-passivation disappeared.

The nanofibers were firstly prepared by static electrospinning process using the fiber-forming copolymer synthesized from N-isopropylacrylamide and N-methylol acrylamide, and then they were shortened and dispersed in tert-butanol by high-speed stirring. Finally, the shortened nanofibers were assembled into nanofibrous hydrogel with hierarchical porous structure by the processes of freeze drying and followed heat treatment. The resultant nanofibrous hydrogel in aqueous medium holds excellent stability, compression resilience and remarkable temperature-responsiveness. When the temperature of an aqueous medium changed alternately between 20℃ and 55℃, in which the nanofibrous hydrogel reached its swelling- and deswelling-equilibrium state within 34 s and 45 s respectively, exhibiting ultra-fast temperature responsiveness. In vitro drug release experiment results show that when the temperature of the phosphate buffered solution of pH7.4 is altered alternately between 15^oC and 47^oC the immersed dextran (model drug) loaded nanofibrous hydrogel can controllably release the drug by ''on/off'' mode.

A new Si-containing BOZ resin monomer (Si-BOZ) was prepared via chemical synthesis method, which was then used as the modifier to blend with BMI, so that to yield the BMI prepolymer with lower viscosity, and the modified BMI resin can also exhibits excellent heat resistance, radiation resistance and mechanical properties. The gelation time of Si-BOZ, BMI, Si-BOZ/BMI resin was studied by plate small knife method, the chemical reactions of Si-BOZ and BMI during curing process were studied by FTIR, and the effect of the addition of Si-BOZ on the curing reaction kinetics of BMI was studied by non-isothermal scanning calorimetry (DSC). The role of parameters in the curing process was also discussed by Kissinger method and Ozawa method.

After spraying acetic acid solution of chitosan (CS) on polyvinylidene fluoride (PVDF) solution film, PVDF porous membrane was prepared by immersion precipitation phase inversion method. The effect of the volume of CS solution on the structure and properties of porous membrane was investigated, and the mechanism of membrane formation was discussed. The results show that with the increase of CS solution volume the porosity and the surface hydrophilicity of the prepared PVDF membrane increased, the content of β crystal on the top surface decreased, while the content of α crystal increased. The top surface of plain PVDF membrane prepared with the PVDF solution film without sprayed CS solution has dense structure, while the upper surface of PVDF membrane prepared with the PVDF solution film after CS solution spraying has porous structure. The cross-section structure of all PVDF membranes is finger like macroporous structure. When CS solution volume was 2 mL, 4 mL and 6 mL, the water flux of corresponding PVDF membranes first increased and then decreased, which are 683.33 L/m²h, 1121.57 L/m²h, 1171.36 L/m²h and 1029.02 L/m²h, respectively. The difference in structure and properties of PVDF membranes prepared with different procedure was mainly due to the different formation mechanism for the top layer of the membranes.

Plates of a novel metastable β-Ti alloy Ti-4Mo-6Cr-3Al-2Sn (mass fraction,%) were solid solution treated at different temperatures for 0.5 h and subsequently aging treated at 400℃ for 4 h. Then the microstructure and room temperature tensile properties of the treated plates were examined by means of SEM, TEM and electronic universal testing machine. Results show that the primary α-phase decreases gradually with the increase of solution temperature. When the temperature rises above the phase transformation point the primary α-phase disappears completely, whilst almost all the plates present the microstructure of coarse β-grains, and the β-grains grow obviously. The 900℃ solution-treated plate presents good compromise in strength and plasticity with yield strength 898.7 MPa, tensile strength 962.5 MPa, and elongation at break 12.7%. Fine secondary α-phase precipitates occurred for the aged plates after solution treated at different temperatures. When the solution temperature is lower than the transformation point, the secondary α-phases are arranged in parallel or at a 60-degree inclination to the primary ones. When the solution temperature is higher than the phase transformation point, the primary α-phase almost disappeared, the precipitated secondary α-phase became coarser with larger spacing. Continuous chain of α-phases precipitated along the original β-grain boundaries in the aged plates, which were subjected to solution treatment in the temperature range 700~900℃, and the plasticity of the alloy is poor at the same time. After a combination solution and aging-treatment of 750℃/0.5 h plus 500℃/4 h, the alloy plate exhibits good compromise in strength and plasticity with tensile strength 1282 MPa, yield strength 1210.6 MPa, and the elongation at break 5.3%.