Effect of forging on the average grain size, residue strain and grain orientation distribution of nuclear grade 316LN stainless steel (316LNss) was studied by means of electron back scattering diffraction (EBSD). The morphology and chemical composition of the oxide films formed on the as-received 316LNss as well as the forged and solution annealed 316LNss after immersion in borated and lithiated high temperature pressurized water at 300 ^oC for 190 h were also investigated. The results show that the average grain size was reduced and the residual strain was eliminated by forging and followed solution annealing. There were no obvious textures in the forged and solution annealed 316LNss. A two-layered oxide film grew on 316LNss after immersion in high temperature pressurized water. The outer layer composes of hydroxides and Fe-enriched spinal oxides and the inner layer composes of Cr-enriched spinal oxides. The forged and solution annealed 316LNss exhibited a lower oxidation rate rather than the as received ones due to the formation of a thinner and more Cr-enriched oxide film. The oxidation mechanism was also discussed.

Silicide coatings on Nb/NbCr₂ alloy were prepared by pack cementation method. The oxidation behavior of the bare- and coated-alloy was examined by isothermal test at 1250 ℃ in static air. The results show that the silicide coatings are composed of (Nb, Cr)Si₂ and (Cr, Nb)Si₂ phases. There exist a transitional layer of (Nb, Cr)₅Si₃ in between the main coating and substrate. The coating growth kinetics at 1250℃ fits to parabolic law. The oxidation of Nb/NbCr₂ alloy resulted in alternate layers of Nb₂O₅ and CrNbO₄ with porous structure, which was wrinkling even spalling off after oxidation. The scale formed on the silicide coating after oxidation at 1250℃ was mainly composed of SiO₂ and CrNbO₄. The scale was relatively dense and had a good bond with the residual coating, thus showing an excellent oxidation resistance.

ABSTARCT Cu thin films were deposited by magnetron sputtering on SiO₂ substrate pre-coated without and with a thin Ti seed layer. Then the surface morphology and micro-texture of the films were characterized by means of electron back-scattered diffraction (EBSD) and atomic force microscope (AFM). The results show that the Cu thin film deposited on the Ti seed layer showed a highly oriented {111} fiber texture. Meanwhile, the generation probability of twins of the Cu thin films induced by annealing treatment could be decreased due to the existence of the Ti seed layer, but voids could occur on the Cu thin film.

Effect of heat treatment processes on the microstructure and mechanical properties of a medium carbon low alloy steel was studied by means of color metallography, XRD and mechanical tests. The adopted heat treatment processes included air quenching and then austempering in salt bath, water-cooling and then austempering in salt bath, as well as directly austempering in salt bath. The results show that after treatments according to the above three processes the steel may exhibited microstructure composed of different amount of bainite and martensite, and better mechanical properties in comparison with the cast ones, i.e. its impact toughness and hardness were increased by 92%-183% and 31%-55% respectively. For the case of air cooling and then austempering in salt bath, the amount of bainite decreased gradually with the increase of air cooling time while the amount of martensite progressively increased, correspondingly its hardness and impact toughness showed a tendency of increase and decrease respectively. The mechanical performance of the medium carbon low alloy steel is closely related to the ratio of bainite to martinsite in the microstructure. It is noted that the steel with a duplex microstructure of 50%-60% bainite and 30%-40% martensite exhibited an optimal comprehensive mechanical performance.

A single phase A-site-deficient perovskite (Y_0.08Sr_0.92)_1-xTi_0.6Fe_0.4O_3-δ (x=0.05, 0.07, 0.10) was synthesized at 1350 ^oC in air by sol-gel method. The effect of A-site deficiency in (Y_0.08Sr_0.92)_1-xTi_0.6Fe_0.4O_3-δ on its phase structure, electrical and ionic conductivity and impedance was investigated. The partial oxygen ionic conductivity decreases with the increasing A-site deficiency, which may be attributed to the tendency for oxygen vacancy ordering. The n-type electronic conductivity in air increases with the increasing A-site deficiency, which may be attributed to the decrease of and due to the possible ionization reaction of ferric iron. The total electrical conductivity of (Y_0.08Sr_0.92)_1-xTi_0.6Fe_0.4O_3-δ (x=0.05, 0.07, 0.10) varies from 0.11 Scm^-1 to 0.26 Scm^-1 at 800^oC. Only one oblique line in high frequency range for each temperature is presented, demonstrating that the electronic conductivity should mainly contribute to the total electrical conductivity. The increase of A-site deficiency is unfavorable for ion conductivity due to a subsequently rising relaxation time.

N-doped titania hollow mesoporous microspheres (N-THS) with good spherical morphology were prepared via LBL self-assembly and calcination method by using triethylamine as nitrogen source. The structure and photocatalytic property of N-THS were investigated with XRD, XPS and UV-Vis DRS. Results show that parts of N inserted into the TiO₂ lattice and replace parts of O, thereby change the chemical state of Ti and O in the lattice. After calcination in a temperature range 400-600℃, anatase TiO₂ was obtained for the N-THS, while rutile TiO₂ appears when calcination at temperatures up to 700℃. The particle size of TiO₂ increases with the increasing calcination temperature. N-THS exhibit strong photoabsorption ability in the visible light region with a clearly red-shifted absorption spectral band. Correspondingly N-THS show good degradation efficiency for methyl orange solution, and along with the decreasing calcination temperature the visible light region absorption ability and the degradation efficiency of N-THS may be enhanced. The degradation efficiency of N-THS calcinated at 400℃ can reach 93.5% after 80 min light irradiation.

The effect of extensometer induced cold-tesile deformation on microstructure and mechanical properties of Ni-based high temperature alloy GH3535 were investigated by means of OM and TEM as well as measurement of true stress-true stain curves. It was found that GH3535 alloy shows characteristics of strong work hardening; cold deformation can result in significant increase of its strength and hardness, whereas decrease of its ductility. With the increase of deformation degree grains were elongated along the deformation direction and twins became profusely lager. The work hardening kinetics of GH3535 alloy is constant with Ludwigson model, dislocation slipping and twin are the main deformation mechanism. With the increase of deformation degree the slip behavior of dislocations changes from single slip to cross slip. When the deformation degree below 30% the work hardening is mainly caused by the dislocation long-range stress field and twin, conversely, for the deformation degree above 30% work hardening is mainly caused by the dislocation short-range stress field and deformation twin.

Powder metallurgy (PM) Ti₂AlNb alloy of Ti-22Al-24Nb-0.5Mo (atomic fraction, %) was prepared from pre-alloyed powder using hot isostatic pressing (HIPing). Compression tests of PM Ti₂AlNb alloy, heat treated PM Ti₂AlNb alloy and wrought Ti₂AlNb alloy with the same chemical composition were conducted on Gleeble-3800 testing machine. The testing temperatures were from 930^oC to 1050^oC, strain rates varied from 0.001 s^-1 to 10 s^-1, and engineering strain was about 50% for each compression. The results show that the deformability of PM Ti₂AlNb alloy is comparable to that of wrought alloy, and heat treatment has no obvious effect on the hot workability of PM Ti₂AlNb alloy. The high temperature flow behavior of Ti₂AlNb alloys prepared by different fabrication routes is similar in this work, while processing windows for PM Ti₂AlNb alloy is broader than casting alloys especially at low temperature or relative high strain rate. PM Ti₂AlNb billets for hot deformation were prepared by a typical powder metallurgy process, and were upset or drawn out to different deformation in two-phase region. Macrostructure of deformed PM Ti₂AlNb billets were observed, no macro crack was found in deformed PM Ti₂AlNb billets and the deformation was uniform. The results of tensile tests show that the deformed PM Ti₂AlNb alloy after heat treatment presents better tensile properties.

Four salicylaldimine ligands (called after 5, 6, 7 and 8 respectively) and their titanium complexes containing bis(phenoxy-imine) ligands, namely [O-C₆H₄-ortho-CH=N-2, 6-(i-Pr)₂-C₆H₃]₂TiCl₂ (called after 13), [O-(5-NO₂)-C₆H₃-ortho-CH= N-2, 6-(i-Pr)₂-C₆H₃]₂TiCl₂ (called after 14), [O-(3, 5-di-Br)-C₆H₂-ortho-CH=N-2, 6-(i-Pr)₂-C₆H₃]₂TiCl₂ (called after 15) and [O-(3, 5-di-C(CH₃)₃)- C₆H₂-ortho-CH=N-2, 6-(i-Pr)₂-C₆H₃]₂TiCl₂ (called after 16) have been synthesized with salicylaldehyde and TiCl₄ as raw materials. The prepared ligands and complexes were characterized by means of ¹H-NMR and elemental analyses as well as mass spectra. After activated with methyaluminoxane (MAO), the complexes 13-16 become efficient catalysts for ethylene polymerization in methylbenzene. Under the conditions of T= 60℃, P=2.0 MPa and n(MAO)/n(cat)=1500∶1, the catalytic activities for the activated complexes 14-16 reached 1022.73-1302.27 gPE / (mmolTihMPa), which were much higher than that for the activated complex 13. The prepared polyethylene possessed a viscosity-average molecular weight in a rang of 19266-44754 measured by viscometry and a molecular weight distribution M_w /M_n in a rang of 1.88-2.12 measured by Gel Permeation in Chromatography. Among others the activated complex 15 displays the highest activity for ethylene polymerization under the same conditions. The characterization by ¹³C-NMR and DSC showed that the polymer synthesized with catalyst of the activated complex 15 was actually a kind of linear and crystalline polyethylene.

The effect of cooling time from 800 to 500℃ (t _8/5) on the microstructure and properties of HAZ for TMCP890 steel has been investigated using Gleeble-3800 thermal simulator. The results show that the coarse grain zone of the HAZ exhibits a microstructure consisted of lath martensite with hardness 334-328HV10 as t_8/5 is 6-20 s. As t_8/5 is 20-30 s, it shows a microstructure of mixture of lath martensite and lath bainitie with hardness 328-305HV10 and B_s raging from 490 to 510℃. As t_8/5 is 150-2000 s, it shows a microstructure of lath martensite and granular bainite with hardness about 270HV10 and B_s ranging from 530 to 570℃. Michio Inagaki formula is suitable for the t_8/5 calculation, accordingly with a heat input E value 10-20 kJ/cm and T₀ range 50-150℃, the hardness of the coarse grain zone could be expected as in a range 318-335HV10.

Microstructure and mechanical properties of the ultra-fine grained high carbon steel Fe-0.8C after multiple laser shock processing (LSP) were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), mini-tensile tests and microhardness measurements. The results show that the ultrafine micro-duplex structure (ferrite+cementite) of the steel was obviously re?ned due to the ultra-high plastic strain induced by LSP. Equiaxed ferrite grains were refined from 400 nm to 200 nm and the particle diameter of cementite lamellae decreased from 150 nm to 100 nm. Accordingly, the strength and microhardness increased greatly and the plasticity was also improved. However, the tensile fracture morphology changed from typical ductile fracture to a mixture of quasi-cleavage and ductile fracture after LSP.

Zr films have been successfully deposited on Mo substrate by pulsed laser deposition (PLD).The microstructure and morphology of the as-deposited films were examined by grazing-incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that the dimension and density of droplets increase with increasing pulse frequency. In the range of 6 to 20 Hz, the average deposition rate decreases with increasing pulse frequency. Under the same conditions, the average nanoparticle sizes of Zr films deposited on Mo increase and then decreases with increasing pulse frequency. Through XRD analysis, it follows that the higher pulse frequency is beneficial to the higher degree of crystallinity of Zr films. However, the pulse frequency has no significant effect on the preferential orientation of crystal planes of the deposited films.