The dislocation boundary structure evolution in AA1050 aluminum alloy during cold rolling from low to medium strains was investigated using electron channeling contrast (ECC) imaging and the electron backscattered diffraction (EBSD) techniques. The results show that the grains are subdivided into a typical cell--block structure and there is a strong correlation between deformation microstructure and grain orientation. Based on the characterizations of grain subdivision and dislocation boundary structure, grains can be classified into three types: Type A---grains containing two sets of geometrically necessary boundaries (GNBs), Type B---grains containing one set of GNBs, and Type C---grains consisting of large dislocation cells structure. Most of grains with Copper, Brass and Goss orientations have Type A microstructure; grains with S orientation have Type B microstructure, grains with Cube orientation have Type C microstructure. The alignment of the extended dislocation boundaries depends strongly on the grain orientation. In most grains the boundaries have inclination angles of ±(30°---40°) to rolling direction (RD), and are approximately parallel to the traces of the most active {111} slip planes as identified by a Schmid factor analysis.

The evolutions of the microstructure and texture of AA1050 alloy cold rolled to large strains have been investigated using electron channeling contrast (ECC) imaging and electron backscattered diffraction (EBSD) techniques. It is found that the microstructure evolves from a cell--block structure at low strains into a lamellar structure at high strains, within which most of lamellar boundaries (LBs) are parallel to rolling direction (RD). Two mechanisms contribute to the microstructure transition, i.e., a gradual reorientation of the cell--block boundaries toward to RD due to the cold rolling deformation (Mechanism I, which is the dominant importance) and the realignment of boundaries to RD as a result of the shearing introduced by S--bands structure (Mechanism II). During this process a significant number of high angle boundaries (HABs) is created, about 47% HABs originate from deformation--induced boundaries at 90% reduction. The number of HABs increases and the spacing decreases with the increase of strains. The texture evolves into typical cold rolling deformation texture components of Brass+S+Copper, and the intensity of the texture increases with the increase of strain.

The microstructural evolution and the coincidence site lattice (CSL) characteristic grain boundary of coarse--grained NiAl alloy during plastic deformation at 1075℃ with the initial strain rate of 8.75×10^-4 s^-1 were studied using EBSD technique. Before deformation most grain boundaries are high angle boundaries, in which several particular angles are predominant, but low angle grain boundaries with misorientation less than 5° occurred successively during deformation. With the increase of the deformation, the misorientations of the newly--formed low angle grain boundaries increase, and grain boundaries with larger misorientation between 6°---15° are formed, and finally high angle grain boundaries with misorientation larger than 15° are formed. There exists a dynamic equilibrium between the formation rate of new low--angle grain boundaries and the rate of changing into higher--angle grain boundaries. Turning of low--angle into higher--angle grain boundaries results in the refinement of grains. The results also show that plastic deformation can change the CSL characteristic grain boundaries of the coarse--grained NiAl, which may improve mechanical properties of the alloy at room temperature.

The macroscopic anisotropies, which are caused primarily by crystallographic textures, have significant effects on the formability of metal sheets and were extensively investigated experimentally and theoretically. Among the numerous theoretical investigations, the phenomenological approach is based on the classical theory of plasticity, in which the plastic behavior of metals is assumed to be well described by analytical functions proposed by Hill, Hosford and Barlat etc.. Because of its simplicity, the phenomenological approach is widely used in finite element method for plastic forming analysis, but this method lacks direct connection between textures and the revealed anisotropies. An alternative is the Taylor--Bishop--Hill (TBH) model which adopts the crystal plastic theory and explicitly takes the crystallographic textures into account, and thus can be used to analyze the anisotropic phenomena on a physical basis. However, implementation of the TBH model into the analysis of industrial forming process is a real tedious task, needing large amount of computational skill and computer resources. Besides, the TBH polycrystalline model does not satisfy the stress equilibrium condition between grains. The viscoplastic self--consistent (VPSC) model for polycrystalline is also a crystal plastic scheme, but it satisfies both strain compatibility and stress equilibrium conditions. In this study, mathematical models for the Lankford coefficient (r value), uniaxial tensile yield stress and yield locus were established based on the polycrystalline VPSC scheme. The effects of ideal crystallographic textures on the macroscopic anisotropy of fcc materials were analyzed. The results show that the minimum r values of Cube and Goss textures appear at an angle of about 45° from the rolling direction (RD), the r values of Cube at 0° and 90° are both approximately equal to unity whereas the r value of Goss at 90° is much higher than that of 0°. For the Cu, Bs and S textures, their maximum r values appear at the angle of about 45° from RD, and their r values of 0° and 90° present some asymmetries. The uniaxial tensile yield stresses of these ideal textures exhibit corresponding characteristics to their r values and the shape of yield locus also varies accordingly. The simulation results are in agreement qualitatively with those of TBH model and phenomenological theory.

In the research field of Bi--based superconductor, the wire, tape and single crystal have been extensively used, but the application of Bi--based thin films is limited due to the appearances of intergrowth and impurity phases. Therefore, various fabrication methods have been adopted to improve the quality of Bi--based thin films. In these methods, molecular beam epitaxy (MBE) is recognized as one of the most adept thin film growth techniques for obtaining single phase, good surface morphology and low concentration of defects. In order to find the optimal preparation conditions, XRD, EDS, SEM, AFM and BiO--(Sr+Ca)O--CuO phase diagram were used in studying the effects of composition, substrate temperature and ozone partial pressure on the formation of Bi₂Sr₂CaCu₂O_8+δ(Bi--2212) thin films in the present work. At the same time, the influences of growth rate, mismatch and buffer layer on the quality of thin films have been analyzed in details. Results indicate that the component range (atomic fraction) forming Bi--2212 single phase is 26.3%---32.4% for Bi--composition, 37.4%---46.5% for (Sr+Ca)--composition and 24.8%---32.6% for Cu--composition. Furthermore, the c--axis epitaxial Bi--2212 thin film with high quality can be obtained on MgO(100) substrate when the substrate temperature and ozone partial pressure are 720℃ and 1.3×10^-3 Pa, respectively. The crystalline quality, surface morphology and electrical property of Bi--2212 thin films have been improved by the alteration of substrates, the adjustment of growth rates and the insertion of Bi₂Sr₂CuO_6+δ buffer layers with different thickness.

The investigation of microstructures of the Bi--2212 and Bi--2223 phases in Bi high temperature superconductors is very significant for improving technology of production and researching superconducting properties and mechanisms. The determination of space groups for the Bi--2212 and Bi--2223 phases is a key problem, which is very complicated because of their incommensurate modulation structures. The supercell structures of the Bi--2212 and Bi--2223 phases with incommensurate modulation structures were determined by convergent beam electron diffraction (CBED). The point group of the supercell of the Bi--2212 phase with type A modulation structure is 2mm, its space group is I2mm. The point group of the supercell of the Bi--2223 phase with type B modulation structure is mmm, its space group is Ibmm. The effects of the rocking curve for the symmetries of CBED patterns were discussed according to experimental results. The simulation results of CBED patterns for the Bi--2212 phase confirmed the symmetries of CBED patterns to be the symmetries of the supercell with modulation structure, but not to be the symmetries of the subcell structure.

The low carbon bainitic steels gain increasing attention due to their high strength, high toughness, and good weldability. To improve the toughness and weldability of this kind of steel the carbon concentration is usually deduced to below 0.06% (mass fraction). As a result the hardenability of the steel is decreased and the ferrite usually becomes the first phase formed during the cooling process before the austenite transforms to the bainite. To decrease the nucleation activation barrier the grain boundary ferrite prefers to nucleate at the prior austenite grain boundaries, which are also potential nucleation sites for the bainite. The prior austenite grain boundaries are occupied by the ferrite, meanwhile ferrite/austenite interfaces are formed, which may influence the following nucleation of bainite. To understand the effect of grain boundary ferrite/prior austenite interface on the nucleation of bainite, a low carbon Fe--C--Mn--Si steel was investigated using optical microscope and electron back--scattering diffraction (EBSD). The grain boundary ferrite and bainite were formed during the two--step isothermal holding. By combining metallographic observation with orientation measurement, two kinds of interfaces were found between grain boundary ferrite and bainitic ferrite: one is non--clear interface, and another is clear interface. The analyses show that grain boundary ferrite has nearly the K--S orientation relationship with the prior austenite on the non--clear interface side, at which bainite nucleates and grow with an orientation similar to the grain boundary ferrite, while the grain boundary ferrite has a random orientation relationship with the prior austenite on the clear interface side, and large misorientation exists between bainite and grain boundary ferrite.

The atomic cluster models of α--Al, η--phase and large angle grain boundary of α--Al in Al--Zn--Mg--Cu alloys have been constructed by computer program. The environment--sensitive embedding energies of Zn, Mg, Cu and H atoms, interaction energies, Fermi energies and densities of state have been calculated by recursion method. The stress corrosion cracking behavior of Al--Zn--Mg--Cu alloys has been analyzed according to the calculated electronic parameters. The results show that Mg, Zn and H atoms are easy to segregate on grain boundaries. Mg promotes the segregation of H on grain boundary, which leads to the embrittlement of grain boundary because of the attraction of Mg to H. Zn increases the difference of electrode potential between boundary and grain, which deteriorates the stress corrosion resistance of Al--Zn--Mg--Cu alloys. Cu reduces the difference of Fermi energies between grain and grain boundary, and lowers the electrode potential difference between grain and grain boundary, which helps to slow up the corrosion process. The calculated results also indicate that the Fermi energy of η--phase is the highest, so η--phase will decompose firstly in the corrosion process as anode. Discontinuous distribution of η--phase along grain boundary can weaken the segregation of H on the grain boundary because of the capture of η--phase to H, and improve the stress corrosion resistance of Al--Zn--Mg--Cu alloys, while the corrosion channel can form and speed up the corrosion process when η--phase distributes continuously on the grain boundary.

The crystallization processes for amorphous Cu were investigated by the molecular dynamics technique with the tight--binding potential, and the changes of pair correlation distribution function, total energy and volume of the system during the processes were analyzed, meanwhile the static structural information on the pair distribution functions and distribution of the coordination numbers were obtained. The results show that the movement of Cu atoms has slightly effect on the short--range ordered structures at the initial heating period of amorphous Cu, 1431 and 1541 bonds change firstly into 1421 bond at the first stage of structural transformation, and the number of 1421 bond increases at above 400 K and gets its maximum at about 600 K, then decreases with temperature increasing and has a quick decline at melting point.

The continuous network of brittle proeutectoid carbide will formed along the grain boundaries when cooled slowly from austenite in hypereutectoid steels. Steels with such high--carbon content have been neglected in industry because of they are inherently brittle. By properly processed, such as hot and warm working (HWW), isothermal warm working (IWW), divorced eutectoid transformation (DET) and divorced eutectoid transformation with associated deformation (DETWAD), the steels will exhibit ultrafine microduplex structure with fine spheroidized cementite (θ) particles dispersed in fine--grained and equiaxed ferrite (α) matrix (grain size is less than 1 μm). This microduplex structure shows superplasticity at elevated temperature and exhibits better mechanical properties at room temperature. However, these processes are relatively complicated and should break the proeutectoid cementiets firstly. By warm deformation of martensite, a simple process and the ultrafined microstructure can be obtained easily. In the present work, the effects of Al on the microstructural ultra--refinement and mechanical properties of hypereutectoid steel during warm deformation of martensite as well as tempering of martensite were investigated by uniaxial hot compression simulation experiment. The results indicate that the warm deformation accelerates the martensite decomposition compared to tempering, leading to the formation of ultrafine (α+θ) microduplex structures. The microstructure evolution of martensite during warm deformation involves the precipitation and coarsen of cementite particles, and the dynamic recovery and dynamic recrystallization of ferrite, while tempering of martensite, the precipitation and coarsen of cementite particles, static recovery and grain growth of ferrite occurred, but no recrystallization of ferrite occurred. With the addition of Al, the decomposition of martensite is impeded during warm deformation and tempering, the microduplex structure is refined, and its strength is improved, while the elongation is not decreased.

For high carbon steels, the (α+θ) microduplex structure consisting of ultrafine ferrite matrix and dispersed cementite particles demonstrates a good balance between strength and ductility as compared with a normal microstructure, i.e., lamellar pearlite in eutectoid steel or lamellar pearlite plus pro--eutectoid cementite in hypereutectoid steel. The divorced eutectoid transformation (DET) has been confirmed to be very effective in ultrahigh carbon steels for the production of the (α+θ) microduplex structure. In ultrahigh carbon steels, DET takes place during slow cooling of a mixing microstructure of austenite plus dispersed undissolved cementite particles formed by the intercritical annealing within the (γ+θ) two phase range. Due to the absence of the (γ+θ) two phase range, DET is difficult to take place in eutectoid steel. In the present work, DET was realized in eutectoid steel by a special thermal--mechanical treatment, which involved two--stage hot deformation in the temperature ranges of A₁ to A_r1 and A₁ to A_c1 and subsequent slow cooling. The microstructure evolution during such treatment was studied by hot uniaxial compression tests using a
Gleeble 1500 hot simulation test machine in combination with SEM and EBSD. The results indicate that during hot deformation in the
temperature range of A₁ to A_c1 after hot deformation of undercooled austenite in the temperature range of A₁ to A_r1 , the re--austenization could be controlled by the applied strain, leading to the formation of the mixing microstructure of austenite plus undissolved cementite particles at certain conditions. During subsequent slow cooling, DET took place, resulting in the formation of an ultrafine (α+θ) microduplex structure with α--Fe
grains less than 3 μm and θ--Fe₃C particles less than 0.5 μm.

The laser glazing rapid solidification can make the dendrite refined and reduce the segregation of alloying elements, so it is very favorable to
mechanical properties of alloys, e.g., the fatigue life of Ni--based superalloy can be prolonged by laser surface melting process due to improved
resistance to stress corrosion cleavage. The laser surface melting process can be used for modification of surface or repair of casting defects (such
as surface porosity, surface stray grains) in single crystal components. Recently, this technique has become an attractive research subject with latent application. A successful laser glazing rapid solidification to single--crystal should ensure the preservation of the single--crystal nature, i.e., the
re--solidified surface layer needs to be epitactic with the substrate. The microstructure after laser re--solidification is closely related to the processing parameters, however, the relationship between microstructure and re--solidification conditions or processing parameters is not well understood
and needs further study. In the present work, the microstructure of laser glazing solidified Ni--based single crystal DD8 was investigated by OM, SEM as well as TEM. The results show that the surface width of the melted pool becomes narrow with an increase of scanning rate, so the melted pool has a relatively high interface/volume ratio which leads to a higher cooling rate. The primary dendrite arm spacing decreases with an increase of cooling rate, and gradually reaches a minimum about only 3 μm, which is two orders of magnitude smaller than that of the untreated part of alloy. EDXA shows that the dendritic segregation is not obvious and the chemical compositions tend to be homogeneous after re--solidification, which is caused by the higher solidification rate and related partition coefficients of alloying elements. The solidified structures are composed of the quasi--plane front, cellular and fine dendrites from substrate to surface of melted pool. The structures in the regions of the quasi--plane front and cellular consist of γ--solid solution and dispersive γ' precipitates with about 20 nm in size. In the regions of the cellular--dendrite and the dendrite, however, there is a eutectic structure with a higher Ti content in the interdendrites. These eutectic structures are small in size and look like leaves. In the transition region, both γ and γ'--phases are not completely melted, and there are some dislocations distributed on the interfaces of the γ'--phase particles induced by thermal stress between γ and γ' phases at higher cooling rate. The unmelted γ' particles can act as nuclei of  the second precipitated γ' phases which have a size of about 10 nm and a pile--up--like morphology.

Fe--Cr base high damping alloys (HDA), as the typical ferromagnetic type HDA, have been well investigated in a long history due to their merits in
low cost and superior workability like steels, and are widely applied for suppression of noise or vibration in many industrial fields. The  agnetoelastic
coupling in ferromagnetic materials is well known to be an important source of internal friction, which could produce a high damping capacity. The
damping mechanism has been mainly attributed to the stress--induced irreversible movements of magnetic domain walls. Fe--(12%---16%)Cr--(2%---4%)Mo (mass fraction) base alloys were found to possess higher damping capacity and better corrosion resistance. As well known Nb, Ti and Cu can improve corrosion resistance of stainless steel. In the present work, dynamic mechanical analyzer (DMA) and field--emission scanning electron microscope (FESEM) were used to investigate the influences of additions of 1.0%Nb, 1.0%Ti and 0.5%Cu on the damping capacity and corrosion resistance of Fe--13Cr--2.5Mo alloy. The results show that addition of 1.0%Nb causes abundant precipitations of (Nb, Mo)C, which
can obstruct the movement of domain walls, and significantly deteriorate the damping capacity at low strain amplitude. At strain amplitudes higher than 3.5×10^-5, the amplitude--dependent dislocation damping Q_dis^-1 is generated due to dislocations interaction with (Nb, Mo)C, so the damping
capacity of Nb--containing alloy becomes higher than other alloys. Addition of Ti or Cu inhibits the precipitation of grain--boundary carbides,
while promotes the intragranular precipitations in the alloy distinctly. As a result, the damping capacity of the alloy with Ti or Cu is slightly lower than that of Fe--13Cr--2.5Mo alloy. Pitting corrosion test indicates that the  three alloying elements can all improve the corrosion resistance of Fe--13Cr--2.5Mo damping alloy. The 1.0%Ti--containing alloy possesses not only high damping capacity but also good corrosion resistance.

Al foam is a structural metal in which gas bubbles are separated by thin Al cell--walls, and exhibits a unique combination of functional properties mainly derived from their cellular structure. Joining is one of important considerable secondary processes that are required for use of work pieces made from Al foam or manufacture of large size Al foam plate. Almost all of the current joining methods have some problems in corrosion resistance, fatigue tolerance, formation of weld and mechanical properties. The joint is further complicated by various cellular structure characteristics that can have a significant impact on the joining process and mechanical properties of the joints. With Zn--based alloy as filler metal, a fluxless soldering method for joining Al foams with porosities of 74.7%---91.6% is proposed. The microstructure of the soldered interfacial region, elemental distributions and phase identification were determined by OM, SEM, EDS and XRD. The tensile and shear strengths of soldered joints, and the relationship between joint bonding strength and porosity were also investigated. The results show that the joining method does not change the cellular structure near the soldered joint, but a dense soldering seam layer is formed. The soldered region consists of Al(Zn) and Zn(Al) solid solutions, Cu₄Zn and MgMnO₃. Major elements of the filler alloy and bases easily diffuse  into each other. The tensile strength of the joints is close to that of the Al foam base, and the shear strength of joint is higher than that of Al foam. The strengths of joints decrease with the increase of Al foam porosity.

Ti60 titanium alloy and Ti₂AlNb alloy have been developed to serve at 600 and 650---850℃, respectively. Because only some regions of hot--end components encounter extreme high temperature environments, it is appropriate to use functionally gradient materials (FGMs) according to the distribution of the working temperature. In this paper, a thin--wall Ti60--Ti₂AlNb alloy with composition gradient was fabricated by laser solid forming (LSF). The phase morphological evolution and microstructure evolution along the gradient direction were investigated. With the increase of Al and Nb contents, a series of phase evolutions along the compositional gradient occurred: α+β→α+α' →α' →α+β→α+β/B2+α₂ →β/B2+α₂→β/B2+α₂+O →B2+O → B2. α--phase can exist in a wide composition range from Ti60 to Ti60--60%Ti₂AlNb (mass fraction). The hardness of the material increases with the increase of Al and Nb contents, and reaches the maximum when B2+O phases appear, and then decreases sharply as obtaining the whole B2 phase at the top position of Ti₂AlNb part. Based on the non--equilibrium phase diagram of the Ti--rich corner, the phase morphological evolution during forming of the gradient materials was explained on combining with the analysis of the influence of the Al and  Nb on the stabilities of α, α₂, β/B2 and O phases in titanium alloys and the effects of recurrent tempering/annealing and heat accumulation in laser solid forming.

With the intensive development of semisolid metal processing technology, an important near--net--shape processing technology, the interaction between melt flow and solidification microstructure becomes gradually one of the important fundamental research fields in materials science. The most important characteristic of semisolid processing is as follows: the solidification microstructure changes markedly under either mechanical stirring or electromagnetic stirring, from dendritic growth under traditional conditions to non--dendritic or globular growth. However, understanding and modeling of the nucleation and crystal growth during semisolid solidification are more difficult than in conventional casting processes due to complicated effects of strong convection. Hence, to date, the formation mechanism of this kind of globular microstructure has not yet been much studied. In the present work, morphological stability of globular crystal was experimentally studied using a succinonitrile--5%H₂O (molar fraction) transparent alloy under different undercoolings and stirring rates. Succinonitrile--5%H₂O transparent alloy was heated to 55℃ (5.1℃ above the liquidus temperature) and held for\linebreak 30 min. The melt was then cooled to a temperature below the liquidus temperature at a cooling rate of 0.1℃/min and a series of stirring rates.  In~situ observation was performed using a stereomicroscope and JVC video camera. The results show that the incubation time for the formation of globular crystal decreases rapidly with the increase of stirring rate. When the stirring rate is low, the incubation time for the formation of globular crystal decreases obviously with the increase of undercooling. When the stirring rate is high, the effect of undercooling on the incubation time for the formation of globular crystal is weak. With the increase of stirring rate, the solid fraction of globular crystal increases at first, and then decreases. When the stirring rate increases to a certain value, the globular crystal will completely disappear. There is a critical undercooling for the transition of growth behaviour of globular crystals. Under the present experimental condition, when the undercooling is larger than the critical value, the size of globular crystal can increase to above 100 μm without globular/dendritic transition. But when the undercooling is less than the critical value, globular crystal will grow to a definite size much smaller than 100 μm. According to the growth behaviors of globular crystal, the semi--solid microstructure could be refined well under an optimized stirring rate and undercooling.

With the trends of higher integration and microminiaturization in electronic packaging, the sizes of the soldered joints are becoming smaller and smaller. The corresponding current density in the soldered joints can easily reach 10³ A/cm² or higher, which makes the electromigration (EM) much more prominent. EM will lead to the atoms to pile up at the anode side and produce voids or cracks at the cathode side. Furthermore, with the stressing time increasing, these voids or cracks will propagate gradually resulting in the soldered joint rupture. EM may induce whisker growth resulting in the short circuit. All these defects can degrade the reliability of the soldered joints. In this paper, the effect of electric current (5×10³ A/cm², 80℃) on the whisker and hillock growth in Cu/Sn--58Bi/Cu soldered joint was investigated by SEM and EDS. It was found that after current stressing for 540 h, the solder at the cathode side is depleted and whiskers appear in the depleted zone, while solder film forms on the Cu substrate at the anode side and a large number of whiskers and hillocks appear on the film. EDS revealed that these whiskers and hillocks are mixtures of Sn and Bi. When the stressing time reached 630 h, more whiskers and hillocks form and more amounts of Cu₆Sn₅ intermetallics form at the interface of solder and cathode. The above facts indicated that the electromigration may induce diffusion and migration of metal atoms, leading to formation of a thin solder film on the anodic Cu substrate. The compressive stress generated by intermetallics formation provides a driving force for whisker and hillock growth on the solder film, and the Joule heating should be responsible for the whisker growth at the cathode side. There is no credible approach for predicting the whisker growth time, growth velocity and whisker length although several mechanisms have been proposed, but are not universally accepted. By general consensus, compressive stress is recognized as the main driving force for whisker growth and a break of the protective oxide on the surface.

During the mechanical loading and unloading process, Tb--Dy--Fe giant magnetostrictive materials can dissipate a mass of elastic energy due to the irreversible movements of non--180° domain walls, which is of interest to be applied in passive damping control systems. The magnetomechanical damping capacity of Tb--Dy--Fe compound is strongly sensitive to the stress magnitude as well as the external magnetic fields. As a new member of the Tb--Dy--Fe family, quaternary Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂compound has been developed as a good candidate in wide operating \temperature range applications. In order to realize the application of Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂ compound in passive damping control system, it is important to systemically investigate its damping capacity under coupled magnetomechanical loadings. In the present work, <110> oriented Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂ crystal was prepared with a growth velocity of 480 mm/h by zone melting directional solidification method. The damping capacity was studied by quasi--static stress--strain measurements under a series of constant magnetic fields up to 0.325 T. Stress ranges from 0 to -10, -30 and -50 MPa were used at room temperature. The results show that maximum damping capacity (Δ W/W) is obtained at zero field. Under certain stress amplitude σ_m, Δ W/W decreases with the increase of magnetic field. A critical magnetic field exists in the damping capacity--magnetic field (Δ W/W--H) curves, and seems independent on the stress magnitude. Under coupled magnetic--stress loadings, the magnetostriction--magnetization curves were measured to analyze the switching process of domains and movements of domain walls, by which an explanation on the variation of damping capacity was given.

Small diameter ferromagnetic metal fibers (Fe, Ni, Co and their alloys fibers) with the anisotropic characteristics are attractive as fillers in polymer--matrix composites, advanced electromagnetic interference (EMI) shielding and wide--band microwave absorbing materials. Because lectromagnetic radiations with high frequencies only penetrate the near surface region of an electrical conductor, the composite material containing metal fibers with a small diameter is more effective than that with a large diameter. The filler of magnetic metal fibers with a diameter of 1 μm or less is therefore required technologically. Although iron fine fibers have been produced and used in several technological fields owing to a low cost, these iron fibers with a high specific surface area are generally not chemically stable due to easily oxidizing in an ambient atmosphere, which lowers their performance. The alloying can improve the anti--oxidation properties of ferromagnetic metal fibers and enhance their magnetic characteristics. In the present work, the nanocrystalline Fe_0.13(Co_xNi_1-x)_0.87(x=0.20, 0.30, 0.50, 0.80) fine fibers were prepared by the organic--gel thermal reduction process using citric acid and metal salts as the raw materials. The structure and morphology of the gel precursors and the fibers derived from these gel precursors in the thermal reduction process were characterized by FTIR, XRD and SEM. The magnetic properties for as--prepared alloy fibers were examined using vibrating sample magnetometer (VSM). The diameters of alloy fibers are in the range of 0.3 to 2 μm and these consist of grains with the size of about 34 nm. The experimental data show that the aligned nanocrystalline Fe_0.13(Co_xNi_1-x)_0.87 fibers exhibit an obvious magnetic anisotropy. This magnetic anisotropy is mainly effected by the magnetocrystalline anisotropy, shape anisotropy and magnetostatic interaction. The magnetizing ease axis for the nanocrystalline fiber is parallel to the fiber axis whilst the hard axis is perpendicular to the fiber axis. The nanocrystalline Fe_0.13(Co_0.50Ni_0.50)_0.87 fibers have a very high remanence ratio of 0.48.

BaHfO3 ceramic scintillator dopped by 0.3%Ce³⁺ (molar fraction) was prepared by co–precipitation method. XRD, TG–DSC and TEM were employed to measure the phase transformation and grain morphology of BaHfO₃Ce. The densification and microstructure of BaHfO3Ce ceramic scintillator prepared in different sintering atmospheres were studied. Results show that there are three stages during the crystallization of the precursor. The near spherical BaHfO₃Ce nanoparticles can be obtained after calcining at 900℃ for 2 h, and the grain size is about 15 nm. The densification and microstructure of BaHfO₃Ce have obvious differences under sintering in air and in vacuum. The fully densified sample was obtained by vacuum sintering at 1750℃ for 1.5 h, and the grain size is about 40—50 μm. The sample prepared by sintering in air has the uneven grain size distribution. 380—420 nm purple and 420—450 nm blue bands appear in the wavelength λ=530 nm excitation spectra of the vacuum sintering scintillator and the as–synthesized powders, respectively. And the peaks in the excitation spectra are at 391, 398 and 445 nm corresponding to 4f →5d energy level transition of Ce³⁺. A comparison for the emission spectra prepared by vacuum sintering shows that the ceramic scintillator has the stronger luminescence intensity than the as–synthesized powders.

The wear performance of Ti6Al4V alloy for clinical usage was modified by dual--ion implantation technique. The samples were implanted firstly with silver ions at a dose of 1.0×10¹⁷ cm^-2, then with tantalum ions at a dose of 1.5×10¹⁷ cm^-2. Nanoindenter instrument was used to measure the variation of hardness with displacement into surface of sample, and multi--functional tribological tester was used to investigate the wear and tribological property. Phase constitution in the surface layer of Ti6Al4V alloy was characterized by glancing angle X--ray diffraction (GAXRD), the X--ray photoelectron spectroscopy was used to analyze the chemical states of elements in the surface layer of sample. The results show that the worn area of Ag+Ta dual--ion--implanted Ti6Al4V alloy is decreased by 77\% compared with untreated alloy. The improvement of the wear property is related to the increase of hardness, long holding time of low friction coefficient and solid solution strengthening induced by Ag and Ta.