Microstructure evolution, grain refinement mechanism and mechanical properties of face-centered cubic (fcc) metallic materials, subjected to equal channel angular pressing (ECAP), were systematically investigated. According to the special shear deformation mode of ECAP, Al single crystals with different orientations and Cu bicrystals with different initial grain boundary directions were subjected to ECAP for one pass, and it is found that shear deformations both parallel and perpendicular to intersection plane play important roles in the ECAP process. Moreover, Al single crystals, Cu single crystals and polycrystalline Cu-3%Si (mass fraction) alloy with different stacking fault energies (SFEs) and special crystallographic orientations, subjected to ECAP for one pass, were selected to experimentally and analytically explore the combined effects of crystallographic orientation, SFE and grain size on deformation twinning behaviors in several fcc crystals. Furthermore, ultrafine grained (UFG) or nanocrystalline (NC) Cu-Al alloys with different Al contents were prepared using multiple-passes ECAP. The results show that the grain refinement mechanism is gradually transformed from dislocation subdivision to twin fragmentation, and the equilibrium grain size decreases with lowering the SFE of Cu-Al alloys. Meanwhile, the homogeneous microstructures of materials with high or low SFE are much more readily gained than those of medium-SFE metals. More significantly, the strength and uniform elongation can be simultaneously improved with lowering the SFE, i.e., the better strength-ductility combination is achieved in the Cu-Al alloy with lower SFE.

The diffusivity of oxygen in liquid silver in the temperature range of 1473 to 1773 K were determined by potentiostatic methods employing the following zirconia base solid electrolyte cell arrangement of cylindrical geometry: (+)Pt ︳air ︳ZrO2（MgO）︳[O]Ag(l) ︳Ir(-). The diffusivity of oxygen in liquid silver was calculated from the change of the external current with time by applying a preselected voltage on the electrochemical cell. The relation between oxygen diffusivity and temperature was given: Do=（1.11+-0.04)*10^(-3)exp[(-25573+-1718)/RT]cm2s-1 （1473～1773K） The present experimental results were in close agreement with those extrapolated from the predecessors’ data at low temperature. The diffusivity of oxygen in liquid silver at 1773K was found to be (1.96+-0.28)*10^(-4) cm2s-1.

Low cost Fe-Mn-Si based shape memory alloys (SMAs) has not got widely applications because of their poor shape memory effect (SME) and the need of thermo-mechanical training, so developing training-free Fe-Mn-Si based SMAs with high memory property is significant. In the present study, it was put forth that the formation of stress-induced ε martensite in a domain manner could improve the SME of Fe-Mn-Si based SMAs and it could be realized through subdividing austenite γ grains into smaller domains using the residual lathy δ ferrite phase. According to Hammar's equivalents, a cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy with Cr/Ni equivalent ratio of 1.85 was prepared. OM and VSM (vibrating sample magnetometer) examination showed that the as-cast microstructure consists of γ austenite and lathy δ ferrite phase, and the lathy δ ferrite subdivided the austenite grains into smaller domains, which makes the stress-induced ε martensite bands form in a domain manner. Because the collisions between domain-like martensite bands were reduced, a high recovery strain of 4.9% was attained in the as-cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy. This result provides a novel way of developing training-free Fe-Mn-Si based SMAs. It can be expected that the SME of cast Fe-Mn-Si based SMAs will be further improved through modifying and optimizing alloy compositions, solidification parameters and heat treatment process.

The microstructure and memory property evolutions of as-cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy with annealing temperature were investigated using OM, ferrite measuring instrument and bending method. The results showed that when the as-cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy was annealed between 773 and 1173 K, its shape memory effect (SME) was further improved. A high recovery strain of 6.4% was obtained only through annealing the as-cast alloy at 973 K for 30 min, which is 1.2% higher than that of the conventional Fe-14Mn-5Si-8Cr-4Ni alloy after four times thermo-mechanical training. When the as-cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy was annealed below 1173 K for 30 min, the morphology of δ ferrite phase was still lathy and it could make the stress-induced ε martensite form in a domain manner during deformation, which is the reason why the good SME was obtained in the as-cast alloy annealed below 1173 K for 30 min. When the annealing temperature was above 1273 K, the δ ferrite phase would dissolve in the austenite and its amount decreased. When the annealing temperature was further increased to 1423 K, the amount of δ ferrite phase remarkably increased and its morphology evolved into the island from the lath. The austenite grains could not be well subdivided into smaller domains due to the decrease of lathy δ ferrite phase or the formation of island δ ferrite phase. The SME of this as-cast alloy dramatically decreased when annealed above 1273 K.

Ni--based superalloy turbine blades produced by Bridgman directional solidification technology are widely used in both aeronautic and energy industries as key parts of the gas turbine engines. Because of existence of complex heat radiation between the shell surface and the furnace wall, precise control of the temperature distribution within the blade is a challenging task. A modified model based on the Monte Carlo ray tracing method was proposed for the three dimensional temperature simulation of the turbine blades during directional solidification process, in which the furnace wall temperature evolution was considered and calculated. Ray refinement in normal direction was applied to improve the heat radiation calculation precision. Three dimensional finite differential grids for turbine blades and two dimensional differential grids for furnace wall were used together to increase simulation efficiency and save memory consumption. Heat transfer calculation of the blades with the modified model was performed and compared with that of the simplified model in which the furnace wall temperature was treated as constant. Experiments were carried out to validate the proposed model in this paper. It was demonstrated that the modified model revealed the furnace wall temperature change during the withdrawal process and its impact on the blade, and simulated the temperature distribution of the turbine blade with a higher accuracy.

Microstructures, mechanical properties and corrosion resistances of 29Cr super duplex stainless steel (SDSS) with N contents of 0.11%, 0.26% and 0.42% have been investigated by XRD, SEM, EDS, electrochemical workstation and XPS. The results show that with increasing N content the distribution of Cr becomes homogeneous, the amount of $\gamma$ phase increases according to a linear relationship of Φ(γ)=60×w(N)+21.97, and the tensile strength and elongation of the steel are improved according to the relationships of σ_b=318.33×(w(N))1/2+626.3 and δ=60×w(N)+10.83, respectively, due to the roles of solution strengthening and reducing (Mn, Cr)S precipitation. In the process of seawater corrosion, α phase in the steel would be corroded first, N can form NH₄⁺ and NO₃^- to promote the re-passivation effect of passive film; and Mo can form MoO₄^2- to improve the stability of passivated layer and strengthen the corrosion resistance of the steel. The higher the N content, the lower the corrosion current density and the better the corrosion resistance for the steel.

Phase selection and microstructure evolution play important roles on processing and property
control of the materials with peritectic reactions. Many interesting microstructures, such as peritectic coupled
growth (PCG), discrete banding, island banding (IB) and oscillatory tree-like structure were observed in directionally
solidified peritectic alloys. In recent years, a number of theoretical models have been developed for the phase
selection. For example, it was believed that peritectic coupled growth is initiated by island banding
and is similar to eutectic coupled growth, discrete banding is shaped by nucleation and lateral spreading of one
phase onto the other phase, and island banding is formed when the nucleation rate of one phase on the other phase
growth interface is higher than a critical value, and etc.. But these models were developed under the assumption
that the growth of the phases are controlled by diffusion only, whereas the actual experimental studies were
mainly carried out in bulk metallic samples with the presence of convection. Although it has been believed that
the convection effects on microstructure evolution are very important and could not be neglected, studies were
seldom carried out in diffusive regime. In this paper, directional solidification of Fe-4.2Ni hypo-peritectic alloy
in diffusive regime was carried out in a Bridgman furnace by placing the samples in 1 mm inner diameter thin
tubes. The experimental results show that various microstructures and phase selections are obtained in the
directionally solidified thin samples at the pulling rates of 15 and 35 $\mu$m/s. Tree-like structure,
peritectic coupled growth and the steadily solidified structure of two phases separated growth are formed at the
pulling rate of 15 $\mu$m/s, and the microstructures evolution is: single phase δ→tree-like
structure→γ and PCG→separately growing δ/γ. At the pulling rate of
35 μm/s, the main microstructure is γ-IB, and the microstructures evolution is: δ→tree-like structure→γ-IB in the center and PCG at the edge→δ in the center
and γ-IB at the edge. As the pulling rate increases from 15 to 35 μm/s, the morphology of tree-like
structure formed by the competitive growth between the nucleated γ-phase and the parent δ-phase
becomes complicated. It is found that the pulling rate plays an important role in both the formation and evolution
of various microstructures.

It has been verified that He embrittlement in metals could be suppressed by proper additions of alloying elements, and this effect is related to highly dispersive secondary phase precipitated in the matrix. Effect of C doping on ion implantated He behavior in Al has been investigated by XPS, XRD, TEM and SEM. It was found that the secondary phase precipitated in the surface of Al doped with C is Al₄C₃. With the increase of the dose of C, the volume of Al unit cell increased, and the preferred orientation of Al surface changed from (100 to (111), which will affect the He behavior in Al. The pre-doped C played an important role in the Al surface blistering induced by He ion implantation, and the extent is dependent on the dose of pre-doped C. When the Al sample was pre-doped by C with smaller fluence (≦5.0×10²⁰ ions/m²), the growth of blisterings is suppressed effectively, and the surface blisterings are distributed more uniformly. However, when pre-doped C has larger fluence (≧1.0×10²¹ ions/m²), the suppression effect of C on surface blistering would be reduced, and even the irradiation damage of He ions (voids and flakings) would appear in the surface. The effect of C doping on the microstructure in Al was also observed.

Hot--die forging+direct aging processing was used to improve the microstructure and
mechanical property of P/M superalloy FGH 4096, a kind of materials used in turbine disk, which includes a
solution treatment at 1130 ℃ for 0.5 h, multiaxially forging (total deformation about 100\%) and direct aging at
760 ℃ for 16 h, in addition, drawing (70%) and upseting (40%)+direct aging treatment has also been
invesigated. OM, SEM and TEM were employed to study the microstructure evolution and strengthen
mechanism. It was found that the direct aging treatment has obvious effect on strengthening, especially, for the
multiaxially forged alloy, in which dynamic recrystallization appeared, and the previous particle boundary is
replaced by clean recrystallized boundary and the grain is refined to about 6 μm. After direct aging the average
size of γ'  phase is 80 nm, and the tangled dislocation is still reserved. The strengthening mechanisms
include grain refinement, clean boundary, thermomechanical deformation and γ' phase precipitation.

The effects of annealing and aging processes on transformation behavior of the low-temperature superelasticity alloy Ti-50.8Ni-0.3Cr (atomic fraction, %) were investigated with differential scanning calorimetry. The A→R/R→A (A-parent phase, R-R phase) type reversible transformation occurred in the 350-450 ℃ annealed alloy upon cooling/heating, the A→R→M/M→R→A (M-martensite) type occurred in the 500 ℃ annealed alloy, the A→R→M/M→A type occurred in 550-600 ℃ annealed alloy, and no transformation occurred in the above 650 ℃ annealed alloy. The effect of the annealing time on transformation behavior of the alloy is not serious. With increasing aging time t_ag, the transformation type of 300 ℃ aged alloy still is A→R/R→A, the one of 400 ℃ aged alloy changes from A→R/R→A to A→R→M/M→R→A, and the one of 500 ℃ aged alloy changes from A→R→M / M→R→A to A→R→M/M→A. With increasing annealing temperature, the R transformation temperature (δ_R) of the alloy increases first and then decreases, the M transformation temperature (δ_M) increases, and the M temperature hysteresise (Δδ_M) decreases. After aging at 300-500 ℃, the δ_R⁴⁰⁰>δ_R³⁰⁰>δ_R⁵⁰⁰. With increasing t_ag, the δ_R and δ_M increase fast first and then tend to stable, and the Δδ_M decreases fast first and then tends to stable. The R temperature hysteresises in both the annealed and aged alloys are about 4 ℃.

Thermodynamic properties of the traditional U720Li alloy and the new Ni-Co base superalloy have been studied using JMatPro and the latest relevant database for Ni base superalloys. The effects of chemical composition on the equilibrium precipitation phases, process-ability and γ/γ' mismatch have been analyzed. It is found that the γ/γ' mismatch increases with the increase of Ti/Al (atomic ratio). The volume fraction of γ' is proportional to the Ti+Al contents (atomic fraction). Therefore, by increasing the Ti/Al ratio and Ti+Al content, the yield strength of alloys can be improved. On the other hand, the γ' solvus temperature decreases by Co additions. As a result, the range of processing temperature is extended. The γ/γ' mismatch also increases with Co additions, which adds additional strengthening to the alloy. Moreover, high Ti/Al ratio or low Co content promotes the precipitation of η phase. Thus, Ni-Co base superalloys with high Ti+Al content, Ti/Al ratio and Co content bear an improved strength, phase stabilities and process-ability.

As a ferroelectric material, BaTiO₃ single crystal has the domain structure which can be changed by the application of mechanical stress and electric field. Therefore, the fracture behavior of the crystal is closely related with the domain switching. To understand the relationship between the fracture behavior and the domain switching clearly, the change of the indentation cracks and domain switching around the indentation under electric field perpendicular to the polarization of the samples were investigated through in situ observations by a differential interference contrast microscopy. The results show that for in-plane polarized sample, after completion of domain switching under the in-plane electric field perpendicular to the polarization of the crystal, the indentation cracks and the domains around the indentation are the same as the new indentation on the sample with new polarization state. In the case of applying in-plane electric field on the anti-plane polarized sample, the speed of the domain switching increases in the initial stage and decreases in the end stage, it has the maximum value as half of the domain switching completed. And the speed fluctuates in the\linebreak first stage.

Alkaline rechargeable batteries, such as Ni/Cd batteries and Ni/MH batteries have been widely used as power sources, however, their further applications are limited due to contamination of Cd in Ni/Cd batteries and lower discharge capacities of Ni/MH batteries. Some metal borides, such as Co-B, Ni-B, Fe-B, V-B and Ti-B, have been known to own very high discharge capacity in alkaline aqueous solution, in which Co--B alloy exhibits the highest reversible discharge capacity and the best cyclic stability. However, the reversible capacity of Co-B alloy prepared by arc melting process is usually less than 250 mA?h/g, which is only one fourth of the theoretical capacity of the alloy electrode (908 mA?h/g). In the present study, chemical reduction method was used to prepare Co-B alloy to further enhance the electrochemical capacity of the alloy. A series of ultrafine powders of amorphous Co-B alloys, Co_0.68B_0.32, Co_0.55B_0.45 and Co_0.50B_0.50, were prepared by reducing CoSO₄ with solution of NaBH₄. Electrochemical measurements indicate that the prepared alloys exhibit excellent electrochemical properties. At a high current density of 300 mA/g, the initial discharge capacities of these alloys are 510.6, 666.4 and 667.2 mA$?h/g, respectively, their discharge capacities still keep 331.6, 379.5 and 390.5 mA?h/g after 60 cyc, respectively. Even at a discharge current density as high as 1200 mA/g, the three alloys still deliver reversible capacities of 336.2, 373.4 and 390.1 mA?h/g, respectively. In the Co-B alloy electrodes, the boron atoms have two functions. First, boron can be oxidized to BO₃^3-, thereby partly contributes to the discharge capacity. Second, most importantly, the gradual dissolution of boron into the electrolyte (in the form of BO₃^3-) during the charging/discharging creates a new surface in the electrodes, which can effectively increase the surface area of the active material in contact with the electrolyte. The alloy with higher boron content thereby can produce a larger reaction surface area by boron dissolution than the alloy prepared with lower B content. So the higher B content in the Co-B alloys can be helpful for improving their electrochemical properties.

Aluminum alloys are extensively used in many fields such as aeronautics, astronautics, vehicle manufactures and living products due to their good mechanical properties and anti--corrosion performance. Traditionally, the most effective corrosion protection technologies are based on the use of Cr⁶⁺ containing formulations to extend the applications of aluminum alloys in high corrosive media such as chlorides containing solutions. However, the recent recognition that chromates are highly toxic and carcinogenic has led to extensive research to develop new alternatives. Many works have been published using different conditions to obtain rare earth (RE) conversion layers on several aluminum substrates. Unfortunately, these reported anti-corrosion technologies based on RE modified films presented several drawbacks including long formation time, high formation temperature and even high potential in some cases. The goal of the present work is to introduce the novel cathode electrophoresis technique to quickly deposit cerium modified film on the surface of Al 5083. The morphology and structure of the RE film were characterized by SEM, EDS and XRD, the corrosion resistance was investigated by EIS and potentiodynamic polarization curves in 0.1 mol/L NaCl solution. The results showed that uniform CeO₂ film of 0.8 μm thickness can be prepared by cathode electrophoresis process in 0.1 mol/L Ce(NO₃)₃ ethanol solution at a voltage of 12 V for 60 s. Polarization curves confirmed its excellent protective property through inhibiting the cathodic reaction. Impedance data collected from EIS in 0.1 mol/L NaC1 solution remained capacitive for 31 d, which indicated the lack of localized corrosion. With the increase of exposure time, the charge-transfer resistance R_p became higher, the surface capacitance C_t nearly kept constant and cracks of the film reduced obviously, demonstrating a self-healing property. Apparently local cathodes were covered during the RE modification processes, thereby reducing the driving force for pitting.

The evolution of corrosion products of 20 carbon steel in simulated humidity atmosphere containing SO₂ was investigated by means of OM, SEM, XRD and localized electrochemical impedance spectrum (LEIS). Results showed ferrous hydroxide film firstly formed on the sample surface; the film ruptured in the acidic medium, and then filaments with green heads occurred. The filaments grew along the grain boundaries and into ferrite grain. Ferrite phase was dissolved when SO₂, O₂ and H₂O continuously penetrated into the ruptured ferrous hydroxide film and sulphate nests formed. Inside the nests FeSO₄ reacted with O₂ and H₂O to form FeOOH, finally the cellular corrosion products formed. The cellular corrosion products and its impedance increased, and the rust layer became even and compact with further corrosion. Cellular products grew faster with the increasing SO₂ concentration.

To meet the urgent demands of future electronic packages, the solder joints need to be increasingly miniaturized. Although the size of solder joints has surpassed 50-100 μm range, further decrease is still necessary. Mechanical property of solder joints is a key factor that influences the reliability of electronic packages and assembly products. As a consequence, it is very important to understand the fracture behavior of solder joints, which can better predict the reliability of solder joints in electronic interconnections. Compared to the large solder joints, the mechanics behavior for the small solder joints is very different, resulting in a series of reliability issues. In this paper, shear test of the as-reflowed and aged Sn3.0Ag0.5Cu solder joints with the diameters of 200-600 μm on Cu pads was conducted, and fracture behavior was observed using SEM. The results show that the shear strengths of both as-reflowed and aged solder joints decrease with increasing the solder joints volumes. At the initial stage of aging process, the shear strength of solder joints decreases remarkably, and will not decrease much with increasing aging time. For the large solder joints, the fracture occurs close to the interface, and the solder joint shows strong brittleness. Whereas, for the small solder joints, the fracture occurs within the bulk solder, and the solder joint shows ductility. SEM images at the interface of solder joints and solder bulk show that the Ag₃Sn intermetallic compounds within the bulk solder and Cu₆Sn₅ at the interface region have a prominent effect on the shear property and the propagation of the fracture, which is the key factor for the volume effect of the fracture behavior of the solder joints. The Ag₃Sn phase inside the small solder joints has fine particle-like morphology and dispersively distributes in the bulk solder, which strengthens the solder joints, however, the Ag₃Sn phase inside the large solder joints has feather-like and dendritic morphologies and makes the joint become brittle.

Arc ion plating (AIP) has been widely utilized in the deposition of various kinds of thin solid films due to the excellent characteristics of the arc plasma produced from an active cathode spot that emits ions of cathode material, as well as electrons. In AIP process, the cathode spot is usually steered by an external magnetic field. Cathode spot motion is the key factor because it affects the physical characteristics of the vacuum arc plasma, the utilization of the cathode material, the emission of macroparticles (MPs) and the quality of subsequent films containing these MPs. Therefore, cathode spot dynamics should be understood practically under a compound external magnetic field, such as in axisymmetric magnetic field (AMF), for industrial applications. An AMF produced by using an adjustable electromagnetic coil associated with a concentric magnetic flux guider was applied to the cathode surface to investigate the influence of the AMF on the arc cathode spot motion. The distribution of the magnetic field was simulated by the finite element method (FEM) software. The magnetic field intensity was measured by an SHT-V magnetometer and the distributions of magnetic field with different intensities were analyzed. Based on the results of FEM simulation and the physical mechanism of the arc cathode spot discharge, the effects of magnetic-field components and AMF on the cathode spot movement were discussed. The results showed that increasing the AMF intensity can strongly influence cathode spot movement. In the case of a weak AMF,  the cathode spot moves randomly on the cathode surface. With increasing AMF, there is an increasing tendency for the cathode spot to rotate and drift toward the cathode target edge. The increase in the transverse magnetic field (TMF) intensity, B_T, can accelerate the rotational velocity of the cathode spot, increase the arc voltage and decrease the arc current. With a relatively strong AMF (B_T≈30 Gs), the cathode spot rotates near the edge of the cathode surface and is confined to a circular trajectory. A new arc cathode spot is ignited, splits, and is extinguished repeatedly on the cathode surface, which can be observed at intervals of about 0.5 s, while there is an obvious erosion track left at the bottom of the cathode edge.

Duplex stainless steels (DSS), consisted of ferrite and austenite, are widely used in oil, chemical, petrochemical, nuclear and marine industries because of their attractive combination of higher mechanical strength and corrosion resistance in various aggressive environments. However, precipitations of detrimental phases, such as chromium carbides, nitrides, intermetallic phases (χ, σ) inevitably occur when manufacturing conditions and welding procedure heat these duplex stainless steels to temperature ranging from 300 to 1000 ℃, which results in a reduction in corrosion properties due to the presence of chromium-depleted zones around these precipitates. In this paper, the microstructure evolution of 2205 DSS was studied qualitatively at 800 ℃ by using Thermo-Calc coupled with optical microscope. The double-loop electrochemical potentiokinetic reactivation (DL-EPR) was optimized through studying the influences caused by four factors (scan rate, temperature, the concentration of the electrolyte and the surface finish). Then the susceptibility to intergranular attack (IGA) of 2205 DSS was tested by optimized DL-EPR. The results indicated that σ phase will be precipitated in the ferrite phase when 2205 DSS aged at 800 ℃, and the volume fraction would increase with the aging time increasing. The optimized DL-EPR test can evaluate the susceptibility to IGA of 2205 DSS both quantitatively and qualitatively, which is proved by the morphologies of the sample after D--EPR test.