The crystallography of fcc/bcc(bct) martensite transformation, including nucleation and growth, has been discussed from the viewpoint of invariant-line and O-lattice theory. The formation of martensite is accomplished by the immigration of well-defined glissile interface (121)fcc type and its misfit dislocations can produce the lattice invariant deformation (LID) on the basis of phenomenal theory of martensitic crystallography (PTMC), however, LID is retarded slightly after the migration of interphase (121)fcc, i.e.a thin plate-like zone exists without LID in martensite near the well-defined interface. When the temperature reduces to the Ms point, the lattice parameter of austenite matrix is √3/2 times that of the martensite without LID. This critical condition for spontaneous transformation agrees with that the stack fault energy in matrix is less than zero according to Olson and Cohen's nucleation model.

A molecular dynamics (MD) simulations was performed to study the thermodynamic behavior of vacancies in crystalline silicon. In the simulation, we adopt the Stillinger-Weber potential used commonly for silicon to describe the interaction between atoms. Two kinds of methods were employed to trace the jump of a vacancy, and its activation energy in the crystal was also calculated. The statistic explanation of the definition of vacancy jump proposed by Thomas was given. Besides, we find that most of vacancy jumps are performed passing through a metastable state.

As one of the most interesting diffusion phenomena discovered by Osinski et al. in 1982, the periodic layer formation during solid state reactions is still far from a satisfactory description. Since the successive layers have facing surfaces with mated topography, it is considered that the seperating of the layer from the reaction front should relate to the diffusion-induced stresses developing within the separating of the layer during solid state reactions. We discovered that the layer is fractal with clusters of phase β(FeSi in diffusion couple Zn/Fe3Si or CoSi in diffusion couple Zn/Co2Si, e.g.) distributing continuously in phase α (FeZn13 or CoZn13, respectively). This empirical fact supports the mechanical-instability model for the pattern formation of periodic-layered structures.

The electronic structure and magnetism of clusters Nin(n=2-6) have been studied by spin-polarized MS-Xα method. The results show that the effect of the cluster symmetry on its atomic magnetic moment and electronic density of states is very notable. Ni6 cluster is an octahedron belonging to Oh point group. Its 3Eg orbital presents strong negative exchange coupling and has a trend of antiferromagnetic couplings. Ni5 cluster is of three-side pyramidal structure belonging to point group C3v. The magnetic moment direction of Ni atom lying on vertex of the pyramid is antiparallel to the moment direction of the Ni atoms lying on underside of the pyramid, which present the characteristic of ferrimagnetic couplings. Compared with metal nickel, the magnetic moments of some clusters are enhanced and some are weakened. The abnormal phenomenon of surface magnetism of ferromagnetic superfine particles can be well explained using this result.

The internal stresses produced by dislocation networks at the γ/γ’ interfaces in a single crystal nickel-base superalloy DD8 has been studied after in phase (IP) and out of phase (OP) thermo-mechanical fatigue (TMF) testing. The results indicate that one of the roles of the dislocation networks at the γ/γ’ interfaces is to relax most of the misfit stress under IP TMF, on the other hand, the existence of the dislocation networks results in the directional coarsening of the γ’ precipitates. While under the OP TMF, the internal stress in the matrix induced by stacking faults does not vary significantly, the γ’ precipitates do not show direction coarsening in OP test.

The effects of mismatch in atomic size and electronegativity of alloying elements on the elemental concentration of sublattices of γ' phase in Ni base superalloys were investigated. The mathematic model of optimizations was established to predict the elemental concentration of sublattices of γ' phase. Ranges of the selected values of concentration variables were determined by use of the iterative and substitutional method. Based on chemical compositions of the γ' phase, the elemental content at the Ni and Al sites in the γ'phase can be calculated with the layered multi-objective optimization algorithm with tolerance. Using the reported data on both the chemical compositions and the lattice parameters of γ' phase, a comparison between the predicted and the reported values of lattice parameters was made through the application of the predicted values of the elemental concentrations of the γ'sublattices to verify the feasibility and the accuracy of the present method.

Cu-12%Ag (mass fraction) filamentary composite was prepared by heavy cold drawing. The evolution of filamentary microstructure and the effect of strain level on the electrical conductivity of the composite were investigated. The mechanism responsible for the electrical conductive behavior was discussed. With increasing draw ratio, the original eutectic colonies develop into fine fibrous bundles and the electrical conductivity decreases. Electrical conduction of the composite depends mainly on the Cu matrix instead of eutectic fibrous bundles. The conductive loss with strain enhancement can mainly be attributed to the reduction of interfacial spacing between the Cu matrix and eutectic fibrous bundle. The quantitative relationship between the electrical resistivity and draw ratio was derived on the basis of a size-effect model and can be utilized to predict the electrical conductive level of the composite under different strain conditions.

Using the thermodynamic model of TiAl binary system, part of phase diagram of Ti-(44-50)Al around the peritectic reaction was calculated and the solidus and liquidus of primary phase β and peritectic phase α were determined and the parameters used for interface response function were obtained. The interface temperatures of primary phase β and peritectic phase α were calculated for different growth conditions. According to the criterion of the maximum growth temperature, the phase selection and microstructure evolution of Ti-(44-50)Al were theoretically studied and a microstructure-selection map of TiAl stable state solidification as a function of the melt composition and the G/v ratio was constructed.

The microstructure changes of pearlitic eutectoid steel induced by cold rolling were investigated by using SEM, TEM and XRD etc. According to the morphological characteristics of cementite lamellae, the deformed pearlite can be divided into three kinds: irregularly bent lamella (pearlite lamella originally inclined with large angles to the rolling plane and irregularly bent after deformation); coarse lamellae with shear-band (the rhomboidal blocks of weakly deformed lamella bounded by shear band) and fine lamella (heavily deformed lamella aligned parallel to the rolling direction with fine interlamellar spacing). As the rolling reduction increases, the proportion of fine lamella increases. Heavy cold rolling also induced the severe plastic deformation and dissolution of cementite.

Nanostructured layer with a certain thickness and grain size of 10-30 nm was synthesized on a 316L stainless steel by surface mechanical attrition treatment (SMAT) for 60 min. The change of microstructure and properties in the surface layer after cross shear rolling (CSR, 80\% reduction) was investigated. The results show that the nanocrystalline structure was still maintained, however, the grain size became finer (5-15 nm) and more uniform and the surface roughness was remarkably reduced. The hardness in the surface layer was slightly increased, but that of the matrix was remarkably increased. The corrosion resistance in 0.05 mol/L H2SO4+0.25 mol/L Na2SO4 solution was improved, but still lower than that of the matrix.

The uniaxial time-dependent strain cyclic characteristics and ratcheting behavior of SS304 stainless steel were studied by cyclic loading experiments at room temperature. The effects of straining and stress rates, hold time and loading chart on cyclic softening/hardening feature and ratcheting were discussed. It is shown that the SS304 stainless steel presents remarkable time-dependent characteristics even at room temperature, the cyclic deformation behaviors, especially for ratcheting, depend significantly on strain and stress rates, holding time and loading charts. Some significant conclusions are obtained, which is useful to establish a constitutive model describing the time-dependent cyclic deformation of the material.

The impacting behavior of Cu particle upon Cu substrate in cold spraying was studied using the finite element analysis, involving the effects of particle velocity and temperature prior to impact on the deformation behavior, temperature increment and contact area at the particle--substrate interface. It was found that with increasing the particle impact velocity the flattening ratio, temperature increment and contact area at the interface increase. It was confirmed that the critical velocity for the onset of shear instability of particle was consistent with that for particle deposition. As the particle velocity is higher than the critical one, the flattening ratio, temperature increment and contact area at the interface increase more significantly, which will benefit the formation of the bond between particle and substrate. With the increase of particle temperature the temperature at the interface increases significantly. The relatively high temperature achieved the melting point of particle material at the localized contact zone may promote the formation of the metallurgical bonding in the coating.

A low carbon low alloy steel with two different types of microstructures was characterized by nanoindentation. The results indicate that the average nanoindentation hardness of martensite is at least 70\% higher than that of ferrite in the dual-phase sample. Since the ultrafine martensite grain is embedded in the soft ferrite matrix, the nanoindentation hardness of martensite exhibits a substrate-effect when the indentation depth is over 40 nm. Due to more carbon atoms partitioning to austenite during intercritical process, carbon content of martensite in the dual-phase sample may be several times higher than the nominal carbon content of the steel, which makes the average nanoindentation hardness of martensite in the dual-phase sample is at least 30% higher than that in the fully martensitic sample. In addition, the possible effects of carbon partitioning on Poisson ratio and Young's modulus of martensite were discused briefly.

The tension fracture behavior of Zr41.25Ti13.75Ni10Cu12.5Be22.5bulk metallic glass is associated with the test temperature and strain rate. At room temperature, the brittle fracture is dominated by the shear band's formation and expansion. A large amount of radiating vein-like morphologies and the liquid droplets can be observed on the fracture surface. The calculation found that the adiabatic heating makes the temperature of the fracture surface layer higher than the liquidus temperature. At the glass transition temperature, the fracture mode is still brittle fracture. Dimples, vein-like morphologies and liquid droplets occupy the fracture surface. The adiabatic heating induces the temperature of fracture surface layer to be higher than the liquidus temperature too. With the temperature increasing or the strain rate decreasing, the necking fracture appears. The fracture surface displays the vein-like morphologies without the liquid droplets. The affection of the adiabatic heating is so weak that the temperature of the fracture surface layer can not increase obviously.

Etching-enhanced 90º domain switching and indentation crack propagating in BaTiO3 single crystal have been investigated using poled and unpoled samples, respectively. The results show that if the poled direction [001] lies in the (100) indentation plane, etching in HCl+HF solution causes the average length of 16 indentation cracks to increase from (140±17)μm to (211±26)μm, i.e., 50% increment. At the same time, the 90º domain switching zones surrounded by the indentation cracks increase also evidently after etching. The reason is due to chemisorption of etching molecular decreasing surface energy. If Vicker's indention is carried out in the pre-etched surface, the average crack length and the size of the domain switching zones are the same with those of etching after indentation. If the [001] poling direction is normal to the indentation plane, there is no effect of etching on the domain switching zone and crack length. For unpoled sample, etching increases the domain switching zone and the crack length from (150±21) μm to (182±30) μm, i.e., about 20% increment.

The Ag-AgCl micro-reference electrodes were fabricated and used to determine the potentials of ferrite and austenite in duplex stainless steel in NaCl solutions separately. The result shows that ferrite has lower corrosion potential than that of austenite. To determine the corrosion behavior for the single phases accurately and obtain more information about the selective corrosion, a capillary-based micro electrochemical system was established. The electrochemical determinations of ferrite and austenite were performed respectively in solutions containing nitric acid and FeCl3. According to the results, ferrite has more noble corrosion potential and low current density in 1.5 mol/L HNO3 and 1.5 mol/L HNO3 + 0.5 mol/L FeCl3 solutions, thus selective corrosion occurred in austenite phase, while, in 1.5 mol/L HNO3+0.1 mol/L FeCl3 solutions, the potential differences between two phases are not obvious, which result in little selective corrosion.

The corrosion morphologies of as-extruded magnesium alloy AM60 in 3.5%NaCl aqueous solutions with pH 3，7 and 12 were observed, and the number and size of corrosion pits were measured. The effect of pH values on corrosion of AM60 and the role of AlMn particles in corrosion were discussed. A corrosion model of AM60 was put forward. The experimental results indicate that the pitting corrosion occurred in an acidic or neutral 3.5%NaCl aqueous solution, the pits initiated in the α matrix around AlMn particles, whereas Al element was dissolved in the rich-Al areas such as AlMn particles and β phase, and the honeycomb morphology was formed on the surface in alkaline solutions. The number of corrosion pits is most at pH 7.

Ni-68.5Al (atomic fraction, %) coatings were prepared on an orthorhombic alloy Ti-22Al-26Nb (atomic fraction, %) by detonation gun spraying (DS). After annealing, the Ni-Al coatings have a good adherence with the substrate, and XRD shows that the coatings mainly composed of $\beta$-NiAl. The influence of Ni-Al coatings on the isothermal oxidation behaviors of Ti-22Al-26Nb was studied in static air at 800 ℃. For the alloy Ti-22Al-26Nb without coating, under high temperature oxidation a mixed oxide scale formed and consisted of TiO2, AlNbO4 and Al2O3, in which TiO2 is the dominant oxide phase and exhibits relatively poor oxidation resistance. The high temperature oxidation resistance of the specimens coated with Ni-Al coatings is remarkably improved due to the formation of a dense and adherent Al2O3scale.

The exchange-coupling interaction between magnetically soft and hard grains in nanocomposite Nd2Fe14B/α-Fe and their effects on the effective anisotropy of materials have been investigated. By testing six different functions, series of curves of effective anisotropy constant versus grain size and volume fraction of the soft phase were obtained. The calculated results show that the effective anisotropy constant decreases with the reduction of grain size and increases with the decrease of the volume fraction of the soft phase. The calculated curves resemble the experimental results.

The quantitative relationship between the nonmetallic particle's redistribution in metal and electromagnetic force (EMF) was developed during the process of unidirectional solidification in electromagnetic field. It was pointed theoretically that controlling the cycle of the electromagnetic field and the solidified parameters could produce a new composite material in which the content of the particles is a function of the unidistance from the growing interface. Experimental results show that by applying periodical electromagnetic force to the unidirectionally solidified hypereutectic Al-19%Si alloy, the primary silicon--rich particles distributed layer by layer, and the surface hardness fluctuated periodically. Through adjusting the frequency of the electromagnetic force and the rate of the solidifying interface, the width between the two adjacent layers could be changed freely.

In situ reactive infiltration technique was utilized to synthesis TiC particulate-reinforced magnesium matrix composites (TiC/AZ91D). The hot compressive behavior of as fabricated composites was studied at strain rates $\dot{\varepsilon} =10 -3-10 -1 s-1 and at temperatures of 573-723 K. The strain rate sensitivity exponent ($m$), apparent activation energy (Q) and their relations with TiC content and temperature were calculated and analyzed according to the true stress-true strain curves. The results show that the compressive flow stress of the composites increases with increasing the TiC content. For the same TiC content, the flow stress decreases with elevating deformation temperatures or with decreasing the initial strain rates. The m value increases with increasing temperature and at the same deformation temperature and strain rate, the m value increases with increasing the TiC content. The Q value depends on the deformation temperature, strain rate and TiC content and its distribution, and the composites exhibit different deformation mechanisms at elevated temperatures.

Al-doped zinc oxide (ZAO) thin films were prepared by middle-frequency alternative magnetron sputtering with ZAO (ZnO+2%Al2O3) ceramic target. IR (infrared reflection) spectrometry was used to examine infrared reflection properties. The influences of film thickness, substrate temperature and argon gas pressure on the performances of ZAO thin films were investigated. The technical parameters for depositing ZAO films with high infrared reflection were determined.