A new topology-related individual grain growth rate equation was derived under the assumption of the statistical grain model. It depicts that the changing rate of grains is related to the grain size and topological properties. The continuity equation from the particle coarsening theory was adapted to grain growth. Based on the grain growth rate equation and the continuity equation, an asymptotic solution was obtained. The solution is an one-parameter family of distributions other than a unique distribution function, which is supported by quasi-stationary grain size distributions obtained from simulations of vertex model, surface evolver, phase-field model and Monte Carlo method.

The plastic deformation process during nanoindentation of Ni tip into Al substrate, including loading, unloading and stress relaxation has been studied by using molecular dynamics simulation with EAM potential. Results showed that a connective neck between the indenter and the substrate will be formed when the indenter approaches and leaves the substrate surface. During nanoindentation, the first dislocation is emitted at a critical shear stress τs=1.9 MPa, and shear bands appear at partial shear stress τd=6.4 MPa. When the indenter moves upwards, a reverse tensile stress appears and results in reverse yield of the substrate and continuous change in dislocation configuration. When the indentation tip is retracted and passed through its initial indentation position, it connects to the substrate by necking, and when the tip broke away from the substrate finally, there still exist some substrate atoms on the tip. Stress relaxation has been observed on the nanoscale, which attributes to heat activated dislocation emission and motion.

The electronic structures of fluorine-doped Y-Ba-Cu-O superconductors are calculated with Recursion method. The electronic density of states (DOS), Fermi energy (EF), atomic valences of different elements are obtained. The results show that the valences of Cu atom increase and those of O atom decrease, which means that the amount of hole carrier of Cu increases and that of O decreases. Fluorine-doping changes hole carrier concentration in the CuO2 plane, and thus improves the superconducting properties of Y--Ba--Cu--O.

The strength of non quenched-tempered steel consists of the strength of fine-grained α-Fe matrix, solution-strengthening, interface-strengthening, dispersion-strengthening (carbides from austenite), and separation-strengthening (carbides from oversaturated ferrite). Based on the strength of α-Fe matrix, the strengthening increments of the above four mechanisms are respectively calculated with the electron number nA on the strongest bond in alloying phase and electron density difference Δρ on biphase interface. A set of strength calculated equations is proposed with the strengthening factors and the weights of C and alloying elements (M) in non quenched-tempered steel, and used in calculation of the end-rolled strength of non quenched-tempered on the basis of composition and the grain size after rolling. In opposition, the optimization between composition and the grain size can be accomplished on the strength proposed by technical standard. So, the end-colled strength prediction from composition, and grain size can be carried out.

High temperature gradient are employed under the directional condition to examine the influence of the ratio of gradient and solidification rate, G/R, on the microstructure of Al-17.5%In (mass fraction) alloys. The experimental results show that the microstructure evolution of monotectic alloy under the directional solidification is similar to the one of eutectic alloy. When steady growth formed, there exists an In-rich zone in the front of α phase and vice versa. The diffusion process plays a dominate role in the steady growth due to the small lamella distance. Unidirectional solidification microstructure of the alloys changes from fibrous structure to regular droplet-like array and finally random dispersion of In droplets in the aluminum matrix with increasing growth rate or decreasing temperature gradient. The change suggests that the transition of monotectic solidification structure has a closed relation to the morphological transition of solid-liquid interface.

The hot deformation behaviors and the microstructure evolution of three low carbon steels with similar C compositions and different Mn mass fractions (0.48%, 0.84% and 1.29%, respectively) are investigated by uniaxial hot compression at deformation temperatures of 700 ℃ and 600 ℃ and strain rates of 10 1 s -1 to 10 -3 s -1. The effect of Mn on dynamic recrystallization of ferrite is analyzed. The results indicate that dynamic recrystallization of ferrite occurs in these low carbon steels under certain deformation conditions, which range is wider as the content of Mn is lower. The effect of Mn on dynamic recrystallization of ferrite is that the increase of Mn content leads to the increases of pearlite amount and the deformation activity energy when deformed in the ferrite region, the former is beneficial to the dynamic recrystallization and the latter is just opposite. Because the latter is dominant, the increase of Mn content in low carbon steel is unfavorable for the progress of dynamic recrystallization of ferrite. At the deformation condition that the progress of dynamic recrystallization of ferrite can occur completely, the increase of Mn content results in a microstructure with finer ferrite grains.

Cr-O-N films with different chemical composition were deposited using arc ion plating (AIP) between NiCoCrAlY coatings and the DSM11 substrate as diffusion barriers. The inhibition effects of the diffusion barriers on the interdiffusion of the alloy elements in the DSM11/Cr-O-N/NiCoCrAlY system were studied after exposured at 900 ℃ for 1400 h. The influences of the barriers on the oxidation kinetics were also investigated. The results indicate that the Cr-O-N layers can change into Al-rich oxide layers with active bonding with the coatings and the substrates during the high temperature exposure. The Al-rich oxide layers hindered the interdiffusion of the alloying elements between DSM11 substrate and NiCoCrAlY coating. Thus the Cr-O-N layers can act as active diffusion barrier. The O and N compositions in the Cr-O-N layer affect the continuity and density of the Al--rich oxide layers, and influence the inhibition effect of the diffusion barriers accordingly. All the Cr-O-N barriers decreased the weight gain of the NiCoCrAlY coatings at 900 ℃. The improvement extent of the Cr-O-N barriers on the oxidation behavior of the NiCoCrAlY coatings is corresponding with the inhibition capacity of the barriers.

Role of the microstructure of cathode materials in the geometrical parameter and migration process of cathode spot is studied on the basis of the observation of microscopic trace of vacuum arc without external magnetic field. Arc erosion pattern shows that spot craters locate on the phases with weak voltage withstanding, whose size, morphology and distribution determine the character of the arc spots. For the cathode alloys with ultra-fine microstructure the spot is dispersed and moves quickly on the cathode surface, indicating the spot motion is controlled by the microstructure of the electrode materials. The spot migration mode changes from the jumping motion to a continuous one when the microstructure scale is less than the spot size. It is concluded that the constituent phases and their sizes are the important factor dominating the microscopic migration mode of arc cathode spots.

Four heats of V and Nb microalloyed 40Cr steel containing 0 to 1.54% Mo were used to study the effect of Mo on delayed fracture resistance. The results of both notched tensile sustained load test and stress corrosion cracking test show that the delayed fracture resistance increases with increasing Mo content. Maximum delayed fracture resistance is obtained at a Mo concentration of about 1.15%. The result of EDS (energy dispersive spectroscopy) analysis shows that Mo tends to segregate in the grain boundary in a scale of no more than a few nanometers. EELS (electron energy loss spectra) measurement indicates that the segregation of Mo in grain boundary tends to increase the strength of grain boundary. The pronounced effect of Mo in raising the tempering resistance and the ability to strengthen prior austenite grain boundary are the main reasons for the beneficial effect of Mo on delayed fracture resistance. Hydrogen trapping effect caused by fine Mo2C precipitation could also improve the delayed fracture resistance. It is also confirmed that the tested steels could have a much higher delayed fracture resistance when the secondary hardening carbides of V and Mo are in the condition of slight over-raging.

Symmetrical push-pull fatigue tests were conducted on as-electrodeposited polycrystalline copper containing a high density of twins. It was found that twins have different effects on fatigue hardening behavior of copper under different plastic strain amplitudes. When plastic strain amplitude was higher than about 8.14×10 -4, twins will elevate fatigue saturation stress and extend stress saturation plateau because of the interactions between twin boundaries and dislocations.

The crystallization kinetics of the Ni45i23Zr15Si5Pd12 alloy has been investigated by DSC and XRD. The process of crystallization is multi-stage proceeding. The isothermal activation energy obtained from Arrhenius equation increases with the process of crystallization. Based on the JMA equation, the average Avrami exponent for the main crystallization process is larger than 3.0, indicating the crystallization to be a three-dimensional nucleation and growth. The large atomic size difference and negative heats of mixing increase the thermal stability of the Ni-based amorphous alloy.

Ferromagnetic shape memory alloys Ni53Mn23.5Ga23.5, Ni54Mn23Ga23 and Ni50Mn27-Ga23 single crystals were prepared by zone-melting unidirectional solidification. The orientations of the cut single crystals were determined by X-ray diffraction method. The Ni-Mn-Ga crystal growth direction is along [100] with the deviation less than 5 circ. The martensitic twins reorientation process was detected by the stress-strain curves. The compression experiments along different directions were performed, respectively. The results show that the compression improves the texture of favorable martensitic variants and turns them into a single martensitic variant by martensite reorientation.

The soft magnetic properties and giant magnetoimpedance (GMI) effect of the amorphous films of Fe88Zr7B5 and (Fe88Zr7B5)0.97Cu0.03 prepared by radio frequency sputtering on the substrate of single crystal Si have been measured. Significant results obtained is that the GMI effect almost can not be detected in the as-deposited Fe88Zr7B5 films, while it becomes evident for as-deposited (Fe88Zr7B5) 0.97Cu0.03 films. The maximum values of longitudinal and transverse GMI ratio are 17% and 11% at the frequency of 13 MHz, respectively, indicating that the amorphous (Fe88Zr7B5) 0.97Cu0.03 films have good soft magnetic properties and GMI effect even though in the as-deposited state.

An in itu XRD method was employed to identify variations of electric domains on the surfaces of poled PLZT samples during an electric fatigue process, and simultaneously, the related remnant polarization was measured. The SEM observation revealed that the major fracture mode for fatigued samples is intergranular. The diffraction intensities, I (002) and I (200), after each cycle decreased and increased, respectively, and their magnitudes of the increment and decrement lowered as the number of cycles increased. It is suggested that the reduction in magnitude of remnant polarization is caused by the reduction in numbers of switch-able domains during a fatigue process. In addition, the incompatible high strain induced the intergranular micro-cracks in the material, which leads the major fracture mode for the fatigued sample to be intergranular. The formation and the elongation of micro-cracks in samples mainly occurred at earlier stage of electric fatigue.