The Cu/diamond composites containing 90% (volume fraction) diamond particles were prepared at 1200°C under a pressure of 5 GPa by high pressure liquid infiltration method, giving a measured thermal conductivity of 662 Wm^-1K^-1. The characterization of composites by means of SEM, EDS and XRD shows that the interfacial bonding of Cu/diamond is strong, and a transition layer exists between diamond and Cu. Besides, some diamond particles are found to be inter-connected. The Cu/diamond composites fabricated by this method exhibited a thermal conductivity far superior to those produced by other means.

In order to deep understand the hydration characteristics of red mud-coal gangue based intermediate-calcium cementitious materials, XRD, IR, TG-DTA and MIP techniques were used to investigate the hydration products and pore structure of the hardened pastes, which formed after a hydration process of the red mud-coal gangue based intermediate-calcium cementitious materials. The results show that the hydration products mainly are C-S-H gel, ettringite and calcium hydroxide. As the dominant products, C-S-H gel and ettringite are principally responsible for the strengthening of the intermediate-calcium cementitious materials. By hydration for 1 d to 90 d, the content of calcium hydroxide increases at the initial stage and later decreases. With the progress of hydration process, the polymerization between Si-OH bonds tends to be easier, resulting in an increasing of polymerization degree of the hydration products. The red mud-coal gangue based intermediate-calcium cementitious materials with CaO/SiO₂ ratios of 0.95 and 1.04 possess good pore structure of the hardened pastes, while the pore structure of the hardened paste for the material with CaO/SiO₂ ratio of 1.13 is relatively poor.

The influence of helium-related defects on hydrogen retention in magnetron sputtered nano-polycrystalline tungsten films, which had been sequentially irradiated by high energy helium and hydrogen ions, was investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM), elastic recoil detection (ERD) and slow positron beam analysis (SPBA). The results show that the helium ion implanted tungsten films would transform from β-W to α-W after annealing. After annealing at 873 K the release of helium atoms increased dramatically, while the open-volume defects and the degree of structural disorders in the films increased. Furthermore, the total retention of hydrogen in tungsten films decreased slightly with the decreasing of helium content.

Creep or stress relaxation is considered as a main mechanism of reducing the springback of titanium alloy sheet during thermal forming process. So far, the difference and relation between the two phenomena have not been clearly explored. In this paper, tests of short term creep and stress relaxation of Ti6Al4V alloy were conducted at high temperature. The microstructure of the tested alloy was observed by using TEM. Effects of temperature, stress and time on creep and stress relaxation behavior were studied, respectively. The correlation and difference between the two phenomena were compared based on relations of creep strain - time and strain rate - time. Results show that creep behavior is controlled by atom diffusion at low temperature under low stress; by dislocation slide and climb at high temperature under high stress. The stress relaxation behavior is mainly governed by dislocation climb. The predicted stress relaxation behavior based on the creep data shows a good agreement with the experiment.

The effect of ultra fast cooling (UFC) during hot strip rolling on the precipitation behavior of cementite in carbon steels and its subsequent strengthening effect have been investigated by controlling the cooling temperatures for three carbon steels with 0.04%,0.17% and 0.5%C respectively. The results show that the refinement of ferrite grains and the reduction of pearlite lamellar spacing might mainly be responsible for the strengthening of the two steels containing 0.04%C and 0.5%C respectively, while no nano-scaled cementite precipitation formed. On the other hand, a large number of nano-scaled cementite precipitates with the size of 10~100 nm formed in the steel with 0.17%C. Therefore, the precipitation of the nanoscaled cementite precipitates could be realized by the UFC process for the plain carbon steel with 0.17%C but with no request for the addition of microalloying elements. Due to the precipitation strengthening of the nanoscaled cementite, the yield strength of the experimental steels with 0.17%C increased with the lowering the finish temperature of the UFC process gradually and typically reached an increment higher than 110MPa. A further thermo mechanical treatment (TMT) after UFC can increase evidently the dislocation density for cementite nucleation, and it will be a feasible way to realize the uniform precipitation of nano-scaled cementite entirely in the microstructure of the steel, thereby further enhancing the strengthening effect. After hot rolling with the UFC and TMT process, the yield strength of the 0.17%C steel may reach a level greater than 650 MPa, in other words, a net increment larger than 300 MPa may be ascribed to the precipitation strengthening effect of nano-scaled cementite.

The influence of draw ratio on the structure and properties of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) hollow fiber membrane which was fabricated by melt-spinning stretching (M-S) method was investigated in this article. The primary FEP hollow fiber membrane structure was compact while the porous structure occurs after stretching. Furthermore, the increase of membrane draw ratios induced the obvious increase of membrane porosity and the N₂ flux while the decrease of the liquid entrance pressure (LEP). Meanwhile, the FEP hollow fiber membrane was applied to the vacuum membrane distillation (VMD) process to compared with M-S PP hollow fiber membrane which was the commercial product. The results show that the hydrophobic properties, LEP and mechanical strength of FEP hollow fiber membrane was better than PP hollow fiber membrane. The strong and stable of hydrophobic properties enabled the FEP membrane unpenetrated, which kept the desalination rate maintain up to 99%. The larger inner diameter (about 0.74 mm) of FEP hollow fiber membrane induced the use of internal pressure VMD type which brought about the higher VMD flux when the feed temperature increased.

The influence of deformation temperature and strain on the microstructure of GH4706 superalloy was studied by means of double-cone samples compression combined with finite element numerical (FEM) simulation. The results show that the dynamic recrystallization (DRX) mechanism of GH4706 superalloy is a discontinuous process associated with a strain induced grain boundaries bulging leading to the formation of nuclei. It is found that the critical temperature (T_DRX) is 975℃, while the critical strain (ε_DRX) of DRX depends on both the solve of η phase and deformation generating heat. When the deformation temperature is slight lower than the T_DRX, η phase will be partially retained in the alloy, which then hinders the migration of sub-grain or grain boundaries. Therefore, finer grain of GH4706 superalloy can be obtained by deforming with a larger strain at a temperature below T_DRX.

The structure of dislocation and grain boundary (GB) in nanostructured Al–Mg alloys processed by high pressure torsion (HPT) was characterized by means of transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results show that the grains less than 100 nm have sharp GBs and are completely free of dislocations. In contrast, a high density of dislocation as high as 10¹⁷ m^-2 exists within the grains larger than 200 nm and these larger grains are usually separated into subgrains and dislocation cells. These dislocations appear as dipoles and loops. Different GB structures including low/high angle non-equilibrium GBs, low angle equilibrium GBs and high angle Σ 9 equilibrium boundaries are characterized by HRTEM. The roles of the very high local dislocation density, the dislocation cells and the non-equilibrium GBs in grain refinement during HPT are analyzed and the refinement mechanisms associated with these structural features have been proposed.

Carbon nanotubes (CNTs) and poly(styrene-co-maleic anhydride) modified CNTs (SMA- CNTs) were blended with an immiscible system polystyrene/nylon6 (PS/PA6) to prepare conductive polymer composites PS/PA6/CNTs and PS/PA6/SMA-CNTs respectively. The PTC (positive temperature coefficient) effect of the composites was investigated. For PS/PA6/CNTs composites, CNTs were selectively distributed in PA6 phase; the percolation threshold was 5% (mass fraction) and a weak PTC effect was observed. For PS/PA6/SMA-CNTs composites, TEM results showed that CNTs were distributed both at the PS/PA6 interface and in PA6 phase due to the induced effect of SMA on CNTs. As a consequence, the percolation threshold decreased to 0.112%. Meanwhile, an especial double PTC effect was observed. The PTC effect was affected by the morphology of PS/PA6 blends. The emerge of PTC effect of the composites with dispersed PA6 phase was attributed to the glass transition of PS phase and the melt of PA6 phase. However, for blends with PS as disperse phase and PS/PA6 as bicontinuous phases, the emerge of PTC effect was due to the melt of PA6 phase.

Pre-alloyed powder of Ti-22Al-24Nb-0.5Mo (atomic fraction, %) was prepared by crucibleless induction melting and gas atomization process. Then with the pre-alloyed powder, a powder metallurgical (PM) Ti₂AlNb alloy was fabricated by a hot isostatic pressing route. The results show that the hot isostatic pressing temperature affects the metallurgical quality of PM Ti₂AlNb alloys; the post heat treatment affects obviously the microstructure and the performance of the PM alloy; a good combination of tensile strength, ductility and rupture lifetime could be obtained through an optimized heat treatment process. It follows that the rupture lifetime of PM Ti₂AlNb alloys was controlled by the interaction of multiple factors such as the sizes and volume fractions of α₂, O and B2 phases after various heat treatments. With the increase of aging temperature (800~850℃), the size of secondary O phase increased and α₂ volume fraction decreased, thereby the rupture lifetime was increased. With the increase of aging temperature (850-900℃), the size of secondary O phase and α₂ volume fraction remain nearly constant. It was the increase of B2 volume fraction and α₂ size that improve the rupture lifetime of PM Ti₂AlNb alloys.

Ti-P polylactide was synthesized by ring-opening polymerization (ROP) of D, L-lactide with bis-(alkoxy-imine-phenoxy) titanium (IV) complex as catalyst. The physico-chemical properties of the Ti-P material were investigated by measurements of contact angle, water absorption rate and degradability, while its biocompatibility to MC3T3-E1 cells, such as the proliferation, adhesion and spreading performance of murine preosteoblastic cells (MC3T3-E1) was also investigated. The results show that the hydrophilicity of Ti-P polylactide is weaker than Sn-P polylactide, inversely, its anti-hydrolysis ability is stronger. In contact with the Ti-P polylactide material, the MC3T3-E1 cells showed excellent activity in proliferation, adhesion and spreading. The rudimental Ti(IV) complex in the Ti-P polylactide exihibits non-toxicity to MC3T3-E1 cell and does not hamper the growth of MC3T3-E1 cells on the surface of the Ti-P polylactide material.