In this paper, dynamic aging behavior and mechanical properties of an Al-Mg-Si alloy were investigated by means of X-ray diffractometer (XRD), differential scanning calorimetry (DSC) analysis, transmission electron microscope (TEM) and tensile test. The dynamic aging was performed on the solution-treated alloy through equal channel angular pressing (ECAP) at different temperatures. The DSC analyses reveal that dynamic aging in the alloys occurred during ECAP. The XRD, DSC analyses and TEM observation reveal that a considerable amount of dislocations and β″ precipitates had already existed during dynamic aging. Combination of high ductility (uniform elongation large than 10%) and high strength was obtained for the ECAPed alloys. The highest ultimate tensile strength and yield strength of the ECAPed alloys are 450 MPa and 425 MPa, respectively. The very high strength and good ductility of the ECAPed alloy can be attributed to the synergistic interaction of the fine β'' precipitates and the high densities of dislocations after ECAP.

An azodye, 3', 5'-dibromo-4-(N, N-dimethyl)aminoazobenzene was synthesized and characterized by IR, NMR, ESI-MS, element analysis and single-crystal X-ray diffraction. Then the azo dyedoped polymethyl methacrylate film was prepared by host-guest doping method. The photoisomerization properties the doped polymethyl methacrylate both in liquid and solidstates were studied by UV-Vis spectrum and fluorescence spectrum. Additionally, the thermostability of azodyewas characterized by TG. The results show that the molecule of azodye crystal exists as trans-isomer, the benzene rings and -N=N- are nearly coplanar. And the azodye both in solvent and film display significant photoisomerization property, with the process describing as the first order kinetics reaction. The fluorescence intensity of the trans-isomer is stronger than that of the cis-isomer. The azodye is stable below 250℃.

Fully densified titanium with ultrafine-grains was fabricated by the sequence of pressing and vacuum sintering followed with a hot isostatic pressing (HIP) with superfine TiH₂ powders as raw material. Then, the influence of the addition of 0.3 mass %Y on the fabrication process and properties of titanium was investigated. Simultaneously, the microstructure, mechanical properties and tensile fractured surface of titanium were systematically evaluated and analyzed. Results shows that, during heating in vacuum sintering process, the Ti powders decomposed from TiH₂ powders were born with outstanding sintering activity. For example, the rapid densification took place at 600~900℃during the sintering process, samples with relative density higher than 97% could be obtained by 2-hour sintering above 1000℃. Noticed that the grain size of the sintered titanium increased when sintering temperature rose, however its average grain size could still remain less than 10 mm when it sintered below 1150℃. The tensile strength was in the range of 700~1032 MPa for the HIP treated Ti without yttrium, while, 750 MPa or higher along with an elongation among 8%~10% for those with addition of 0.3% Y. It is considered that the mechanism of making fine and ultrafine grain titanium from superfine TiH₂ powders could come down to that: Firstly, decomposition of superfine TiH₂ powders granted the newly produced Ti powders with ultrafine initial grain size by inheritance. Secondly, the solid dissolved H atoms, which released during decomposition, in the Ti powders could segregate at crystal defects and thus play a role as an impediment to grain growth during sintering process.

Nanometer sized Al₂O₃ reinforced Al-Zn-Mg-Cu matrix composites were subjected to treatments in high pulsed magnetic field with different magnetic induced intensity 2T, 3T and 4T. The results demonstrate that the residual stress arrives to a minimum of -1MPa by an applied 3T pulsed magnetic field, which decreased by 102.4% compared to that of the original composite. The applied magnetic field can relax the long range distance stresses between areas with dense and sparse dislocations respectively; Meanwhile, the magnetic field increases the mobility of dislocations and accelerate the release velocity of internal stress, then the residual stress is, thereafter, lowered. The tensile strength increased with the enhancement of magnetic induced intensity. By 4T magnetic field the introduced mass factor, which is a combined parameter to represent the tensile strength and elongation, was enhanced by 12.7% compared to that of the original composite. The high dislocation density is beneficial to the dislocation induced strengthening. Besides, an other important reason lies in that the applied magnetic field may facilitate the formation of metastable η'(MgZn₂) phase as the main precipitates, which somewhat substitute the common η (MgZn₂) phase. Thereby, the increase of η'(MgZn₂) can improve the strength and toughness of composites. Furthermore,based on the first principle the density of electron spin state is calculated, which corresponds to the bonds formation process. By 2T magnetic field treatment, the fractograph of the composite exhibits the characteristic of ductile fracture that corresponds to a higher elongation of 9.3%, which is 12% higher than that of the original composite.

The friction properties and wear mechanisms of two types of Al₂O₃-based micro-nano-composite ceramic tool materials were investigated by sliding wear against austenitic stainless steel 1Cr18Ni9Ti. The results indicate that the friction coefficient decreased but the wear rate increased with the increase of load and sliding speedfor the two materials. In comparison with Al₂O₃-(W, Ti)C_μ-TiC_n, the Al₂O₃-TiC_μ-TiC_n ceramic tool material exhibited better wear resistance , thus was much suitable for cutting austenitic stainless steel. In the sliding process, the steel reacted with Al₂O₃to form FeOAl₂O_3, which made the metal transfer to the ceramic disk, and couldeffectively decreased the friction coefficient. The main wear mechanism of Al₂O₃-TiC_μ-TiC_n ceramic tool material is adhesive wear, while adhesion and fracture for the Al₂O₃-(W, Ti)C_μ-TiC_n.

The composite powders of nylon 12 (PA12) and polystyrene (PS) with different mass fraction were prepared by mechanical mixing method and then work pieces of the composite powders was prepared by selective laser sintering(SLS). The effect of the PA12 / PS ratio on the mechanical property, dimensional accuracy and fractured microcosmic morphologies of the sinteredwork pieces were investigated. The results show that when the mass fraction of PS exceeds 40% the mechanical properties of the sintered specimens decreased obviously and when mass fraction of PS is 20% the tensile strength, breaking elongation, flexural strength and flexural modulus are increased by 7.08%, 10.19%, 6.51% and 8.89%, respectively in comparison with the sintered specimens of PA12. And the dimensional accuracy was also increased.

The chitosan/sericite composite film was prepared by blending plate-like sericite and chitosan. The Scanning electron microscope result indicated that the composite film has typical “brick-mortar” orientation microstructure. The mechanical properties (tensile strength and elongation at break) of the film were enhanced apparently with the incorporation of sericite, whilstthe films preserved good flexibility on account of the unique structure. Furthermore, the composite film exhibited excellent properties in transparency and insulation.

Effect of pre-strain and aging temperature on mechanical property and microstructure of X70 pipeline steel was investigated by means of scanning electron microscope ( SEM ) and transmission electron microscope ( TEM ). The results indicate that the X70 steel shows a microstructure compopsed of granular bainite, acicular ferrite and M/A. The aging temperatures below 300℃, exhibit nearly no effect on the microstructure and the tensile strength of the steel. With the rising of aging temperature, the quantity of activated interstitial atoms, therewith, the pinning effect on dislocations increases, which leads to the gradual increase of the yield strength; However, when the temperature raises to above 200℃, the recovery of pinning effect occurs resulting in the decline of the yield strength. With the rising of aging temperature, the hardening of material induced by the increased cottrell atmosphere and precipitations leads to the decline of the impact toughness. With the increase of the pre-strain, the increment of dislocations may lead to the increase of yield strength, and the stress concentration will increase at boundries of the hard brittle phase M/A, therewith increase the probability of the formation micro-cracks, as a result, the impact toughness delines.

Four kinds of asphalt binders, 70#A base asphalt, SBS modified asphalt, Sasobit warm mix asphalt and rubber modified asphalt are prepared, then the water induced damage of them was studied by laboratory tests under different conditions (in dry or wet atmospheres, for as prepared or aged asphalts ). The surface morphology of the asphalts was characterized by means of atomic force microscope (AFM), while the adhesion force between the asphalt and the mineral aggregate was measured. The results show that, under the dry condition, the base asphalt show stronger adhesive ability with the mineral aggregate compared with the modified asphalts, but also have relatively large dispersion and fluctuation in the tested results. Under the wet condition, the adhesion forces of the as prepared base asphalt, Sasobit warm mix asphalt and rubber modified asphalt all decreased to some extent, among others the as prepared SBS modified asphalt exhibited higher adhesion force, showing stronger water damage resistance ability. The aging process significantly lowers the moisture erosion resistance ability of the base asphalt, making it more sensitive to moisture and more vulnerable to water damage. The aging also depresses the water damage resistance ability of SBS modified asphalt.

Composite materials of LiAlH₄/4MgH₂+5% (mass fraction) M (M = NbSi₂, Ni₂Si and Nb₂O₅ respectively) were prepared by mechanical alloying in hydrogen atmosphere, and the hydrogen storage properties of the composite materials, as well as LiAlH₄ and MgH₂ were investigated. The results show that the kinetics property and thermodynamic property of the 4MgH₂/TiH₂ can be improved by adding NbSi₂, Ni₂Si and Nb₂O₅ respectively. DTA curves (by a heating rate 5 K/min) show that the peak temperature within the low temperature range of the hydrogenation for the corresponding composite materials decreased by 19 K, 15 K and 23 K respectively, especially the catalyst effect of which become more obvious after adding Ni₂Si and Nb₂O₅. The activation energy of the LiAlH₄/4MgH₂ composite is 145.71 kJ/mol, however, after adding Ni₂Si and Nb₂O_5, which decreases to 142.12 kJ/mol and 115.12 kJ/mol respectively.

Hydroxyapatite coatings were deposited on the Ti6Al4V surface by hydrothermal-electrochemical deposition method in an electrolyte composited of 0.025 mol/L Ca²⁺, 0.015 mol/L H₂PO₄^- and 0.1 mol/L NO₃^- with addition of 2.5×10^-4 mol/L Na-Citrate . The effect of the citrate and deposition time on the composition, microstructure, crystallinity and thickness of coatings as well as the bonding strength between the coating and the substrate were investigated. The results show that: in comparison with the electrolyte without citrate, HA coating formed in the electrolyte with addition of citrate exhibits uniform and compact appearance with smaller gain size, which covers entirely the substrate, correspondingly the bonding strength between the coating and the substrate increases from 15.39 MPa to 24.31 MPa. The thickness of HA coating increases non-linearly with deposition time. With the increase of deposition time, the orientation index of the (002) plane of HA increases first and then decreases, which reaching a maximum for 2 h deposition while the coating has much smaller grain size; the crystallinity and bonding strength of HA coatings all increase first, and then decrease, which come to peak values, ca 75.7% and 24.3 MPa respectively by 2 h deposition.

The atomic oxygen (AO) irradiation induced erosion of carbon nanotube (CNT) arrays has been investigated by ground-based atomic oxygen simulation facility. The heights and the surface morphologies of CNT arrays before and after AO irradiation have been characterized by scanning electron microscope (SEM). The results show that CNT arrays can be etched away in AO environment, but the erosion rate of CNT arrays varied with the radiation flux of AO. The morphologies of CNT arrays are also quite different from those before AO irradiation. The erosion of CNT arrays can be attributed to the bombardment effect and the oxidation effect of AO. Finally, a model for describing the process of AO erosion of CNT arrays is proposed.