TiZr-based amorphous alloys with different Nb amount, given by (Ti_45.7Zr₃₃Ni₃Cu_5.8Be_12.5)_(1-0.01x)Nb _x (x=0, 2, 4, 6, 8, and 10, denoted as Nb0, Nb2, Nb4, Nb6, Nb8, and Nb10) were prepared via copper mold casting method. Then the effect of Nb addition on the performance of the alloys was investigated by means of uniaxial compression testing, XRD, TEM and SEM+EDS. The results show that with the increasing Nb content the grain size and volume fraction of the β-phase increased, but the deformation-induced martensitic transformation was suppressed; The plasticity of the amorphous alloys was greatly improved, while the yield strength gradually decreased. Notably, the repeatability of the mechanical properties of the amorphous alloys was improved with the addition of Nb. For the amorphous alloys that may undergo deformation-induced phase transformation, such as Nb0~Nb4, homogenous α'' martensite with a small lath can effectively induce the formation of multiple shear bands. For the amorphous alloys that cannot undergo deformation-induced phase transformation, such as Nb6~Nb10, many dislocations may occur in the β-phase and they accumulated at boundaries to form dislocation steps, which would trigger the formation of multiple shear bands and finally improve the plasticity of amorphous alloys.

The microarc oxidation coating doped with coprous oxide was prepared on the surface of TC4 Ti-alloy by adding different amount of cuprous oxide particles into the electrolyte. The microstructure and properties of the cuprous oxide doped microarc oxidation coating were investigated by means of scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscope (XPS) and microhardness tester. The results show that the surface of the microarc oxidation coating doped with cuprous oxide is porous, but the number and size of micropores are small. However the doped Cu oxides are present in the coating in two forms, namely copper oxide and cuprous oxide. Compared with the microarc oxidation coating without doping of cuprous oxide, the wear resistance and antibacterial performance of microarc oxidation coating doped with different amount of cuprous oxide are significantly improved in artifitial seawater, but their corrosion resistance degraded.

Firstly, a complex nucleating agent (GO-SB) was synthesized by hydrothermal method with graphene oxide (GO) and sodium benzoate (SB) as raw material, and then nanocomposites of nylon 6 (PA6) /GO-SB were prepared by melt blending method with PA6 as matrix and GO-SB as complex nucleating agent. The effect of the introducing GO and SB separately, and GO-SB simultaneously on the morphology, mechanical and thermal-property of PA6 based nanocomposites were investigated. The results show that there are electrostatic interaction and π-π conjugation between GO and SB, and the addition of SB can promote the formation of γ-crystals in PA6. GO-SB was uniformly dispersed in PA6 matrix as heterogeneous nucleating agent, which could induce the increase of crystallization temperature, crystallinity, and thermal deformation temperature of PA6 based nanocomposites. The tensile strength and impact strength of PA6/GO-SB (100/0.05/0.25 in mass fraction) nanocomposites are 69.9%, and 157.1% higher than those of pure PA6, respectively. The tensile strength, impact strength and elastic modulus of PA6/GO-SB (100/0.05/0.25) nanocomposites were increased by 13.6%, 186.4% and 52.6%, respectively, compared with those of PA6/GO-SB (100/0.3/0) nanocomposites. Compared with k=0.238 W/m·k of the pure PA6, the thermal conductivity k=0.536 W/m·k of PA6/GO-SB (100/0.3/0) nanocomposite is increased by 125.2%; while the thermal conductivity k=0.854 W/m·k of PA6/GO-SB (100/0.05/0.25) nanocomposites is increased by 258.8%.

A mixed liquid crystal was firstly prepared with liquid crystals 4-Cyano-4'-pentylbiphenyl (5CB) and 4-[trans-4-[(E)-1-propenyl] cyclohexyl] benzonitrile in a ratio of 5∶1 as raw material. Then the plain liquid crystal 5CB and the mixed liquid crystal were compounded with the pretreated carbon nanotubes (CNTS) respectively, which were characterized in terms of their photoelectric and dielectric properties. The results show that the addition of CNTS affects the threshold voltage and dielectric anisotropy of the liquid crystal systems, as a result, the dielectric anisotropy increases by 4.671%, and the flexural elastic constant also increases; The addition of CNTS also affects the response time and viscosity coefficient of the liquid crystal systems, while the viscosity coefficient decreases by 25.131%. The experimental results also show that the dielectric anisotropy of the mixed liquid crystal is higher than that of the plain liquid crystal 5CB, while the decrease of response time and viscosity is more obvious. The greater advantage of the mixed liquid crystal is that the doping of carbon nanotubes can result in significant improvement in the physical parameters and display performance of the composite system. At the same time, the theoretical research results show that the binding energies of carbon nanotubes and liquid crystal molecules are between those of liquid crystal molecule pairs and carbon nanotube pairs respectively, as a result, dipole moments may be induced by the asymmetric charge distribution of the liquid crystal molecules adsorbed on carbon nanotubes, which can well interpretate the fact that the doped carbon nanotubes can improve the dielectric anisotropy of liquid crystal materials, while reduce the response time.

Aiming to the problem of surface roughness caused by the adhesion of powder on the surface of TC4Ti-alloy fabricated by Selective Laser Melting (SLM), the influence of chemical etching process, including the formula of etching solution and process parameters, on the surface roughness of the SLMed Ti-alloy was investigated. The results shown that the ratio of HF/HNO₃ of the etching solution and the etching time are the main influencing factors. Among them, HF play an important role in reducing the surface roughness of the fabricated Ti-alloy. However, this reducing effect of HF will be weakened as the ratio of HF/HNO₃ decreases. For a constant ratio of HF/HNO₃ (say HF/HNO₃=1/4), the surface roughness decreases obviously with the increasing etching time, but when the etching time is too long, it will cause damage to the substrate. After etching in the solution of HF∶HNO₃=1∶4 for 9 minutes, the surface roughness of the fabricated TC4 Ti-alloy is 2.52 μm. At the same time, the etching process has little effect on the size of the sample (with c.a.0.12 mm of thickness reduction), in other words, the etching process reached an optimal state at this time.

The 8Cr4Mo4V steel for aviation bearing manufacturing was subjected to graded quenching at different temperatures after being vacuum heat-treated. The effect of vacuum graded quenching on microstructure and mechanical properties of 8Cr4Mo4V steel were investigated by scanning electron microscope, XRD, Rockwell hardness tester, impact tester and rotational bending fatigue tester. Results show that the graded quenching 8Cr4Mo4V steel presents a microstructure of lower bainite, martensite/retained austenite and carbides. With the increase of graded quenching temperature, the number of precipitated carbides in the quenched and tempered steel increases, while the amount of retained austenite decreases. When the graded quenching temperature is 580℃, the bainite volume fraction of the quenched steel reaches a maximum of 13.87%, and the residual austenite volume fraction is 28.59%, and then after tempering, the precipitated carbides volume fraction and the Rockwell hardness reach the maximum namely 4.37% and 62.38 HRC respectively, in comparison to other desired graded quenching temperatures. The vacuum graded quenching can improve the comprehensive mechanical properties of 8Cr4Mo4V steel. In other word, the 580℃×10 min vacuum graded quenching treated 8Cr4Mo4V steel presents impact toughness and fatigue limit of rotational bending 23.3% and 110 MPa respectively higher than those of the traditional vacuum quenching treated ones.

First, two organic clays, manely reactive BBDMP30-clay and non-reactive CPDMP30-clay were synthesized, and then two epoxy resin/clay nanocomposites with different interfacial strength were prepared with the two organic clays as reinforcer respectively. The two epoxy resin/clay nanocomposites were characterized by transmission electron microscopy (TEM) and tensile test with dynamic mechanical analysis (DMA). Further, the effect of interfacial strength on mechanical properties were investigated. The results show that the two nanocomposites have almost the same random peeling structure. The reactive type BBDMP30-clay can improve the thermal/mechanical properties of the composites more effectively than the non-reactive type CPDMP30-clay. When the clay mass fraction is 3.5%, BBDMP30-clay can increase the tensile strength of nanocomposites by 250%, while CPDMP30-clay can only increase the tensile strength of nanocomposites by 190%. BBDMP30-clay increased the glass transition temperature (T_g) of the nanocomposites by 6.5℃, while CPDMP30-clay only increased the T_g by 2.5℃. These differences can be attributed to the difference of the interfacial strength of the two nanocomposites.

FeCr-ODS ferrite alloy was fabricated via a novel fabrication process of pre-oxidation treatment followed by powder forging proposed by the authors. The prepared alloy was characterized by means of SEM, XPS, EPMA and TEM techniques in terms of the generation, evolution of oxides on the surface and interior of the powder, as well as the type and distribution of oxide nanoparticles in the fabricated ODS ferrite alloy. The results show that an iron oxide film formed on the surface of powders during low temperature oxidation. By the subsequent heating process, the iron oxide could react with Y and Ti to form complex oxide Y-Ti-O nanoparticles. The evolution of oxide dispersoids during the course of fabrication was characterized to clarify the contribution of powder forging to dislocations and nanoscale precipitates. Fine Y₂TiO₅ nanoparticles uniformly distributed in the matrix, and a small number of Y₂O₃ particles aligned along the grain boundaries by this manufacturing method.

The high-temperature deformation behavior of high Nb containing TiAl alloy during step-by-step hot compression process was studied. Results show that the workability of high Nb containing TiAl alloy was improved after one hot compression deformation due to the increased volume fraction of equiaxed γ grains and α grains, as well as the decreased volume fraction and size of lamellar colony. Accordingly, based on the processing map and microstructure optimization, the optimal rolling process can be acquired as: the rolling process with strain rate lower than 0.5 s^-1, deformation strain less than 25% in the early deformation stage and deformation temperature higher than 1150℃ was determined. Correspondingly, a large size of 600 mm×85 mm×3 mm high Nb containing TiAl alloy sheet with good surface quality and defect-free was successfully fabricated by hot pack rolling with 5 passes of large deformation rolling. The microstructure of the as-rolled high Nb containing TiAl alloy presented fine duplex microstructure with mean grain sizes of less than 5 μm. At room temperature, the as-rolled alloy exhibited yield strength, ultimate tensile strength and ductility as 948 MPa, 1084 MPa and 0.94%, respectively. The tensile strength at 800℃ also remained as high as 758 MPa.