Surface modification of biomedical metal materials is an effective strategy to enhance its osteogenic biological activity， which can greatly reduce the time for forming a strong chemical bonding between the implant and the human hard tissue. This has great significance to ensure the rapid recovery of patients after implantation surgery. In this work， a facile two-step modification method of alkali heat coupled with pre-calcification is carried out to treat the biomedical titanium tantalum alloy （Ti∶Ta=43∶57， mass ratio）， and its osteogenic bioactivity is evaluated by simulated body fluid （SBF） immersion tests. The results show that no bone-like apatite coating is deposited on the surface of TiTa with alkali-heat treatment after soaking in SBF even for 18 days. While the TiTa alloy treated with alkali-heat and pre-calcification exhibits excellent in vitro osteogenic bioactivity. When the modified TiTa alloy is incubated in SBF for only 3 days， its surface is entirely coated with a newly formed spherical clusters of the hydroxyapatite （HA） coating. The boosted osteogenic bioactivity of TiTa alloy modified with alkali-heat followed by pre-calcification is a synergistic result of multiple factors. That is， after hydrothermal treatment of TiTa alloy in NaOH， a porous， coarse and super-hydrophilic surface， with a static water contact angle from initial （54.9±2.1）° to （11.2±2.4）°， is formed， which is beneficial to the adsorption and spreading of SBF. After further pre-calcification treatment， initial crystal nuclei of calcium and phosphorus compounds are successfully introduced into the surface of TiTa， which can rapidly induce calcium and phosphate ions to precipitate and grow into HA during the SBF immersion process.

To overcome the drawback of the brittle borides formed in the stainless steel joint brazed using Ni-based filler metals and further improve the mechanical properties of the joint， a small amount of Cu powders are added into the BNi-2 filler metal to suppress the formation of brittle borides in the joints. The 304 stainless steels are brazed using the BNi-2 and BNi-2 with Cu as filler metals， respectively. The influences of holding time， brazing temperature， and Cu content on the microstructure and mechanical properties of the brazed joints are investigated. The results indicate that for the BNi-2 filler metal， increasing the brazing temperature and time are favorable for reducing the boride content formed in the joint center. In addition， increasing the brazing temperature and time can accelerate the intergranular diffusion of borides， thereby leading to a degradation of joint shear strength. For the BNi-2 filler metal with Cu， when the Cu content is 1%（mass fraction，the same below）， the borides in the joint center are inhibited remarkably， forming a full Ni-based solid solution in the joint center. The joint shear strength obtained is （713.9±16.4） MPa， which is 19% higher than that of the joint without Cu additive. The joint failure occurs at the base metal/filler metal interface， recognized as a ductile fracture. However， when the Cu content increases to 5%， the borides reprecipitate in the joint center， resulting in the reduction of shear strength. In this case， the joint failure evolves to a composite mode with the co-existence of ductile and brittle fracture.

This study addresses the issue of magnetic property degradation during the welding of 1J85 permalloy. Comparative experiments are conducted on 1.5 mm thick annular 1J85 permalloy using two processes： plasma arc welding （PAW） and plasma arc heat treatment welding （PAHTW）， to systematically investigate the effects of these processes on the microstructure and magnetic properties of welded joints. The microstructure， elemental distribution， magnetic permeability and coercivity of the joints are analyzed using optical microscopy， scanning electron microscopy， energy-dispersive spectroscopy， and soft magnetic property testing. The results show that under the PAW process， the morphology of the weld joint exhibits a funnel-shaped structure with a wider top and narrower bottom； under the PAHTW process， multi-layered regional boundaries are formed in the weld zone， with significant grain growth， reduced number of cellular subcrystals， and decreased grain boundary density. Energy-dispersive spectroscopy analysis indicates that the content of the non-magnetic element Si in the weld zone relatively reduces by approximately 50% compared with that in the PAW process. Compared with the PAW process， after PAHTW treatment， the initial magnetic permeability of the joint increases from 40.12 mH/m to 78.81 mH/m， the maximum magnetic permeability increases from 72.63 mH/m to 113.41 mH/m， and the coercivity decreases from 1.70 A/m to 1.24 A/m.

In situ synchrotron radiation X-ray imaging and diffraction are employed to investigate the deformation behavior of Mg-3Al-1Zn alloy with different twin contents under uniaxial compression. The as-received magnesium alloy is compressed by 4.3% and 9.4% strain to fabricate twins with different contents， the pre-compressed and as-received magnesium alloys are subjected to uniaxial compression under the same condition， and the macroscale stress-strain curves， mesoscale deformation imaging sequence， and microscale X-ray diffraction patterns are obtained simultaneously. The imaging sequences are analyzed via digital image correlation method to resolve deformation fields， and the X-ray diffraction patterns are integrated to identify deformation twins. The results show that abundant ｛1012｝ and ｛1012｝-｛1012｝ twins are activated in the as-received and pre-twined magnesium alloy during uniaxial compression， respectively. Both ｛1012｝ and ｛1012｝-｛1012｝ twins can boost the strain hardening rate by slowing the strain localization process. Compared with the 4.3% pre-compressed sample， more ｛1012｝-｛1012｝ twins are formed in the 9.4% pre-compressed sample， leading to higher efficiency in slowing down strain localization， so that the strain hardening rate and its increase rate are at a high value during uniaxial compression.

Utilizing laser processing techniques to fabricate groove-shaped microstructures on the surface of Ti-6Al-4V alloy， and an oxide film is prepared on the surface of the textured samples using thermal oxidation method. Friction and wear tests are conducted to investigate the tribological behavior of Ti-6Al-4V alloy subjected to different surface treatments under ambient dry sliding conditions. Surface morphology， cross-sectional morphology， elemental distribution， surface microhardness before wear testing， as well as microstructural and three-dimensional wear profile changes after wear testing， are analyzed using scanning electron microscopy （SEM）， energy-dispersive X-ray spectroscopy （EDS）， three-dimensional optical microscopy， and micro-Vickers hardness testing. The advantages of laser-textured combined with thermal oxidation treatments compared to single laser-textured or thermal oxidation treatment are revealed， as well as the mechanisms of wear resistance and friction reduction. The results indicate that the laser-textured combined with thermal oxidation samples exhibit more stable friction coefficients with less fluctuation compared to samples undergoing single treatments. At a normal load of 3 N， the wear rates laser-textured combined with thermal oxidation samples decrease by 66% and 68% relative to the single laser-textured and single thermal oxidation samples，respectively. As the normal load increases to 10 N， the wear rate reductions are 27% and 38%. Furthermore， the laser-textured combined with thermal oxidation samples show the disappearance of abrasive wear and a reduction in adhesive wear phenomena. They can simultaneously possess the ability to capture wear debris like a single laser-textured samples and the excellent load-carrying capacity of a single thermal oxidation samples， thereby forming multi-film protective mechanism on the substrate and effectively enhancing the tribological performance of Ti-6Al-4V alloy surfaces under dry friction conditions.

Nano-SiC/Al-Zn-Mg-Cu composites are prepared by high-energy ball milling combined with spark plasma sintering （SPS） and hot extrusion. The precipitation hardening characteristics， aging precipitation behavior， and microhardness of nano-SiC/Al-Zn-Mg-Cu composites are studied by differential scanning calorimetry （DSC）， synchrotron radiation X-ray diffraction（SR-XRD）， transmission electron microscopy （TEM） analysis and microhardness test. Results show that the addition of nano-SiC particles increases the thermal diffusion activation energy of η'and η phases， and inhibits the growth of the precipitated phase in the composites. Moreover， adding SiC particles increases the concentration of η' phase and refines the η phase at the grain boundaries， which enhances the precipitate-strengthening effect. With the increase of aging time， the density and size of η' phase within the grain increases， and gradually transforms into η phase. Meanwhile， the η phase precipitated along the grain boundary coarsens. Increasing the aging temperature can increase the free energy of the composite system and the diffusion rate of the solute atoms， promoting the growth of η' phase and η phase and the transformation of η' to η phase. The addition of 3%（volume fraction）SiC nanoparticles increases the microhardness by about 50%， and the peak aging time decreases from 64 h to 16 h with the aging temperature increasing from 100 ℃ to 140 ℃， but the aging temperature change has little effect on the hardness value of peak aging.

As an effective approach for improving the match of strength and ductility of martensitic stainless steel， the processing of quenching and partitioning （Q&P） is seldom implemented in industrial practice of commercial steels due to two factors： the one is difficulty in accurate controlling the quenching suspending temperature， and another is large amount of carbide precipitation within martensite during partitioning. In this work， an experimental medium-carbon martensitic stainless steel of 30Cr15NiMo is designed and fabricated. The effects of processing parameters on microstructures revolution are investigated， and the mechanism of strengthening and toughening is clarified as well， through microstructure characterization and mechanical property testing conduct on Q&P treated samples. The research results show that， the martensitic start （M_s） temperature of the testing steel is approximately 200 ℃ after complete austenitization， and a compound microstructure of martensite and retained austenite can be obtained after the sample being cooled to ambient temperature. The excellent comprehensive mechanical properties of 1255 MPa in yield strength， 1631 MPa in tensile strength， 18.5% in elongation and 42% in area reduction can be achieved in the hot rolled testing steel plate subjected to tempering-assisted partitioning treatment at 480 ℃. The microstructure characterization confirms the volume fraction of retained austenite is approximately 20.2%， and small amount of cementite precipitated inside martensite， these factors improve the uniform elongation and non-uniform elongation synergistically. The research results provide fundamental basis for further optimizing in chemistry and processing.

The fracture morphology of the specimens is observed using a scanning electron microscope， and the failure modes of the 2D C/SiC composites under the action of tensile creep and fracture are investigated and analyzed. The crack extension process of the 2D C/SiC composites under the action of tensile creep is observed using the home-built high-temperature tensile creep tester and the in-situ crack extension observation system. The fracture process and failure mode of 2D C/SiC composites under tensile creep are investigated and studied. The experimental results show that the creep rupture time of 2D C/SiC composite without notch is greater than 8000 s at 1000 ℃/50 MPa， the steady state creep rate is 5.11×10^-8-1.36×10^-7 s^-1. The existence of the notch shortens the steady state creep stage significantly， and the creep time is shortened by about 2000 s， and the steady state creep rate increases to 2.0 × 10^-7 s^-1. The two stages of decelerated creep and steady state creep are the key features of the tensile creep curves of 2D C/SiC composites at 1000 ℃/50 MPa. Crack expansion is mainly concentrated in the late stage of steady state creep phase， where the carbon fiber will rapidly undergo oxidation reaction in the high temperature environment and micro-cracks sprout in the matrix. When the specimen internal micro-crack saturation will produce macro-cracks， macro-cracks connected to the internal pores of the material to form a coherent expansion path， resulting in the rapid expansion of cracks， crack expansion caused by fiber blocking led to cracks occur many times the deflection of the creep specimen macroscopic fracture is jagged， and there are a large number of fibers pulled out.

Using NaOH/urea/water system as the solvent and anhydrous ethanol as the anti-solvent，a series of regenerated cellulose nanocrystal （RCNC） with controllable molecular weights and gradually decreasing yet stabilized sizes are prepared through a multi-step precipitation method. High-performance liquid chromatography and transmission electron microscopy results reveal that the sizes of the obtained RCNC gradually decreased as their molecular weights decreased （from 36 kDa to 9 kDa）. Pickering emulsion stability tests indicate that the prepared RCNC exhibits excellent emulsifying properties. Among them，RCNC-15 with an average molecular weight of 15 kDa exhibits the best emulsifying performance，with the smallest emulsion droplet size and the optimal emulsion stability at low concentrations. Using the RCNC with the best emulsifying properties as the carrier，zinc oxide nanoparticles are grown in-situ on it to conduct emulsion-assisted photo-degradation tests of Nile red. The degradation rate reaches 99.5% within 100 min，indicating that the obtained RCNC could be served as an efficient emulsion-assisted reaction carrier.

Supercapacitors，as a new type of energy storage device between traditional capacitors and secondary batteries，show broad application prospects in many fields. In this study，graphene oxide （GO） is prepared by the Hummers method，and ZIF-8 with a regular dodecahedral structure is grown in-situ. Then，the ZnSe@rGO nanocomposite is successfully prepared via the chemical vapor deposition （CVD） method. SEM images show that the ZnSe@rGO nanocomposite has a regular dodecahedral structure. ZnSe grows along a layer of yarn-like rGO surface and exhibits good crystallization performance. BET tests indicate that the specific surface area of ZnSe@rGO is 57.36 m²·g^-1，which is larger than that of ZIF-8@GO. Electrochemical performance tests of the samples show that，in 3 mol·L^-1 KOH solution，the ZnSe@rGO nanocomposite has a high specific capacitance of 971.4 F·g^-1 at a current density of 1 A·g^-1，confirming the material has good pseudocapacitive behavior. Moreover，at a current density of 2 A·g^-1，the ZnSe@rGO nanocomposite still maintains 74.49% of its initial capacitance and nearly 100% Coulombic efficiency after 5000 cycles，demonstrating excellent cycling stability. When assembled into an asymmetric supercapacitor （ZnSe@rGO∥AC），the device achieves a specific capacitance of 112.5 F·g^-1 at a current density of 1.0 A·g^-1. It also delivers an energy density of 40.0 Wh·kg^-1 at a power density of 2057.1 W·kg^-1，making ZnSe@rGO a promising candidate material for asymmetric supercapacitors.