Influence of 1 at.% Sb addition on martensitic transformation and Curie point of Co41Ni32Al27 alloy is investigated for the first time by optical metallograph, SEM, EDX, XRD, DSC and VSM methods. The results show that martensitic crystal structure of Co41Ni32Al26Sb1 alloy is still L10 type. Both martensitic transformation temperature Tm and Curie point Tc is linear relation to quenching temperature. Tm increase 9K and Tc increase 7.5K for every 10K increasing in quenched temperature. Quenched from same temperature, Tm of Co41Ni32Al26Sb1 alloy is higher than that of Co41Ni32Al27 alloy by 70K，meanwhile Tc is higher by 15K. The melting point of Co-Ni-Al alloy decreases by the Sb addition, eutectic structure appears in Co41Ni32Al26Sb1 alloy annealed at 1623K, indicated that the alloy is partial melted. The martensitic transformation temperature range of Co41Ni32Al26Sb1 alloy is 20-28K, less than half that of Co41Ni32Al27 alloy. This is a very important result to benefit the achievement of large magnetic field induced strain on Co-Ni-Al based alloy. The results of Tm and Tc were explained by total average s+d electron concentration and magnetic valence number Zm separately.

The interfacial microstructure of SiC fibre reinforced Ti-22Al-23Nb-2Ta matrix composite, which was prepared by hot isostatic pressing (HIP) of power-clothed precursor wire, was investigated by analytical transmission electron microscopy (TEM). A new interfacial structure, consisting of fine grain TiC+TiSi, equiaxed TiC and （Al,Ti）Nb2 phase layer, was found at the fibre /matrix interface of the composite. A formation mechanism of the interface is proposed: the reaction of Ti with C-coating results in the formation of TiC; as a consequence, Nb is rich in Ti-depletion layer beneath TiC layer and forms (Al,Ti)Nb2 phase.

The microstructures of annealed Zr(CrV)2 Laves-phase intermetallic compound were studied using high-resolution transmission electron microscope (HRTEM). The results show that annealed Zr(CrV)2 exhibits a lamellar microstructure under low magnification and character of long-period stacking structure as well. Further studies by HRTEM and Fast Fourier Transformation (FFT) indicate that the structure of annealed Zr(CrV)2 is C36 combined with eight-layer and six-layer long-period stacking structure. The effect of V on the stability of ZrCr2 Laves phase was finally discussed in this paper.

In this paper, the site occupancy of transition metal elements, such as V, Ti and W, in the C15 NbCr2 Laves-phase compound were investigated by the full-potential linearized augmented plane-wave-method within the generalized gradient approximation. The calculated results show that there are different site substitution behaviors for these alloy elements in NbCr2. V preferentially substitutes the Cr sites, and W has a weak site preference on the Cr site. Ti preferentially occupies the Nb sites in NbCr2. The calculations of the heat of formation show that only V occupying the Cr sites and Ti occupying the Nb sites can stabilize NbCr2 Laves phase. The site substitution behaviors of those transition metal elements in NbCr2 are also discussed with the calculated electronic structure of the ternary Laves phases.

The nucleation and growth behaviors of high-temperature δ during austenite (γ) → ferrite (δ) + liquid (L) phase transformation in an AISI30 stainless steel have been observed in-situ by using a confocal laser scanning microscope. The results show that δ appears prior from the γ crystal boundary at the temperature range from 1300 to 1400 0C, and appears at full blast in the γ gains above 1410 0C. The γ→δ+L phase transformation is controlled mainly the diffusion of Ni atoms near the γ/δ/L phase interface. With the increment of temperature risen rate, the size of δ gain decreases, the δ/γ planer interface becomes unstable, and a certain secondary branch appears. The δ grows mainly in the non-faceted style at first. Twin-crystal is the key shape of the sidestep forming in the δ/γ interface. The faceted δ trends to passivate its edge and transfers to non-faceted style with the γ →δ+L phase transformation. The mechanisms of the growth interface instability for δ are discussed by using the critical wavelength to stabilize a planar interface theory. The transformation reason for growth style of δ is analyzed by using the crystal dynamics theory.

The interrelationship of crack nucleation to martensite transformation and plastic deformation has been studied in situ using a differential interference constrast (DIC) microscopy for a notched sample of Ni2MnGa ferromagnetic shape memory alloy . The result showed that martensites form firstly during loading and there was a plastic zone when stress concentration ahead of a crack is large enough . Microcrack initiated preferentially along the interface of martensite , but also initiated in the plastic zone . With increasing the load , microcracks initiated discontinuously along the martensites and connected through shear microcracks in the ligaments , resulting in a resistance curve increase behavior .

The effect of applied stress and inclusion on hydrogen blistering in wheel steel has been investigated. The results show that the critical current density for forming blistering during charging under sustained stress is the same with that of the sample without stress, and the critical diffusible hydrogen concentration for forming blistering under sustained stress,Cσ* is located within the scatter interval of C0* for the sample without stress. t test shows that there is no effect of the stress on C0*. However the threshold current density and diffusible hydrogen concentration for hydrogen-induced delayed fracture under sustained stress are ith=3mA/cm2 and Cth=0.52×10-6, respectively, which are smaller than the corresponding values for forming hydrogen blistering, i.e., ic=5mA/cm2 and C0*=1.18×10-6 . Hydrogen blistering do not preferentially form along the inclusions for the samples without stress, however, the blistering preferentially form along the lengthened inclusion under sustained stress, resulting in decreasing C0* from 1.18×10-6 for the samples without stress to 0.56×10-6 in the sample containing lengthen inclusion under sustained stress.

The cyclic oxidation behavior of Ti50Ni44Al6 and Ti50Ni41Al6Nb3 alloys at 1073 K in air have been investigated. The addition of Nb could improve the oxidation resistance of the alloys. During the oxidation of Ti50Ni44Al6 alloy, both internal and external oxidation were observed, forming TiO2/Al2NiO4 and TiNiO3, respectively. The oxidation kinetics of the Ti50Ni44Al6 obeys linear law. After addition of Nb, only external oxidation occurs during the oxidation of Ti50Ni41Al6Nb3, forming an oxide mainly composed of TiO2. The oxidation kinetics obeys parabolic law. The mechanism for the improvement of oxidation by Nb addition was discussed. Nb impedes the inward diffusion of oxygen and the outward diffusion of metallic elements, resulting in a deceleration of the oxidation.

Effects of electric field annealing on plastic strain ratio (r value) of IF deep drawing steel sheet were studied by mean of tensile test. The results show that electric field annealing improves the average plastic strain ratio ( value). This is due to the fact that the electric field annealing reinforces the γ-fiber texture and weakens the a-fiber texture that deteriorated the plastic strain ratio.

The phase structure and magnetostriction were first studied in the small atom B element doped (Fe0.81Ga0.19)100-xBx(x=0~20) alloys. The as-cast (Fe81Ga19)100-xBx alloys for x= 1 exhibits A2 and Fe2B phases, while possess Fe2B and A2+L12 eutectic phases for x=5, 10, 15, 20; Oil-quenched at 800℃ for 3h (Fe81Ga19)100-xBx alloys for x=1, 5 exhibit Modified-D03 and Fe2B phases, while possess Fe2B and Modified-D03+ L12 eutectic phases for x=10, 15, 20. The saturation magnetostriction (λs) of the as-cast (Fe0.81Ga0.19)100-xBx (x=0~20) alloys exhibits two peaks when x=1 and x=10; the λs of the oil-quenched alloys increases first and then decreases with increasing B content. The λs of (Fe81Ga19)90B10 reaches the maximum, 80％ larger than the oil-quenched Fe81Ga19, attributing to the emergence of Modified-D03 phases in the oil-quenched alloys.

The effects of cerium-rich mischmetal ranging from 0.02% to 1.2% on the grain size, dendrite size, eutectic microstructure and characteristic parameters of the cooling curve of AZ91D magnesium alloy were investigated. The results showed that when adding mischmetal into AZ91D magnesium alloy, mischmetal reacted with Al8(Fe,Mn)5 or ε-AlMn phases which served as the heterogeneous nuclei in the melt, and formed Al-RE-Mn phases, thus it reduced the amount of the heterogeneous nuclei and resulted in the grain and dendrite coarsening. In addition, mischmetal reacted with aluminum to form Al11RE3 phases, consumed a part of aluminum atoms, and reduced the amount of the eutectic microstructure. Under the solidification condition of the sand mold, the lowest temperature of the primary phase nucleation rised with increasing the amount of mischmetal addition, while the minimum temperature and growth temperature of the eutectic reaction both increased firstly and then decreased. Consequently, the temperature difference of the eutectic recalescence fluctuated.

The effect of uniaxial pre-compression on the microstructure and stress rupture properties of an second generation single crystal superalloy without Re is studied. The pre-compression is performed in vacuum at 1050℃ by 180MPa/6h and 220MPa/6h respectively. It is shown that P type γ’ paralleling to stress is formed during pre-compression, which is more regular in the 220MPa compressed sample. Moreover, dislocation networks are deposited on γ/γ’ interface in vertical channels, while a few dislocations have cut into γ’ particles in 220MPa compressed sample. The effect on stress rupture lifetime vary with the test conditions, but pre-compression increased the elongations under all test conditions.

The single-cell and serial double-cell impedance measurements of five points on the same epoxy coating covered mild steel were performed by electrochemical impedance spectroscopy (EIS) technique. The reliability of double-cell method was demonstrated by the relationship between polarization resistance values (Rp, where Rp=Rc+Rct+Rdiff) of organic coated-metal systems with single-cell and double-cell measuring methods, respectively. The experimental results suggested that when the impedance difference of two epoxy coated-mild steel electrodes selected in the double-cell was large, the value of impedance of epoxy covered metal system with double-cell was close to that of the electrode with higher impedance, and the relative error between the sum of Rp of single-cells and Rp of double-cell was larger; for two electrodes with similar impedance values were in series, the Rp of double-cell was equal to the sum of Rp of two single-cells, and the relative error of these results was smaller; both impedance values of two electrodes were small and they were in series, one could find that Rp of double-cell was not the same as the sum of Rp of two single systems and there was larger relative error between these results.

Based on a one-dimensional planar sheath model, the kinetic model of pulsed bias arc ion plating (PBAIP) sheath according to temporal evolvement and its analytic expression are presented. Combining the measuring results of plasma parameters in PBAIP process, temporal evolvement disciplinarian of the thickness of PBAIP sheath and ion current density in the sheath, and the effect of pulsed bias magnitude on sheath thickness and ion current are simulated and analyzed. The results indicate that both the thickness of stable-state sheath and the time of sheath formation are far less than the values reported by PSII. The expanding of the PBAIP sheath almost follows the real-time change of pulsed bias voltage, and the sheath thickness under pulsed bias voltage nearly equals to that under DC bias voltage. The results are helpful for making the most of advantages of PBAIP and improvement of its process control.

To describe the transient transformation process of surface depression of full-penetrated weldpool, a sudden variation of welding process parameters (welding current and welding speed) at some moment when the weldpool has reached quasi-steady state simulates the disturbance during practical welding process. Through employing the developed model for transient behaviors of tungsten-inert-gas arc weldpool, the dynamic transformation process of surface depression of full-penetrated weldpool after a sudden variation of welding process parameters in quasi-steady state is numerically simulated, and basic data are obtained to guide designing weld penetration control system. The welding experiment results show that the predicted surface depression for both top and bottom sides of weldpool is in agreement with the measured one.

It has been found that the undercooling of Fe40Ni40P14B6 alloy melt can be enhanced greatly by using fluxing purification technique. The results show that the solidification structures of the alloy at different undercooling are quite difference and the microstructure can be refined significantly by increasing the undercooling. When the undercooling is large enough, nanosize solidification structure can be obtained. In present work, at the undercooling of 360K, the as-prepared bulk nanocrystalline alloy possesses the average grain size of 40nm. It has been found that the alloy melt will experience Spinodal decomposition resulting in appearance of the network characteristics in solidification structure if the undercooling is large enough. The thermodynamics analysis results indicate that the characteristic sizes of the network structure resulted by Spinodal decomposition are close related to the undercooling of the alloy melt, the larger the undercooling, the smaller the grain size.

The microstructure of SiC particle reinforced Al-7.0%Si (mass fraction) composite made by stir casting was simulated by a modified cellular automaton method coupled with finite difference method and three-dimensional mathematical and numerical models under normal solidification condition were established including macro heat transfer, nucleation, equiaxed dendrite growth and particle pushing. The effects of different particle volume fractions on macro heat transfer, composite microstructure and particle distribution were studied. The simulated results can clearly show the evolution of the microstructure of composite and particle clustering phenomena caused by particle pushing. The simulated results are in good agreement with the experimental. With the increase of SiC particle volume fraction, solidification time is decreased. At the same time, composite matrix grains are refined and particles are distributed more uniform.

The experiments of individual and dual laser beam brazing were carried out, in which the base metal is galvanized steel sheets and CuSi3 is used as filler metal. A finite element model was developed for the thermal process on the basis of heating behaviors analysis, and the transient temperature fields in the braze joint were calculated. In the model, the surface heat source was used to model laser heating the surface of filler metal and base metal and heat transfer induced by the flow of melted feller metal was simulated by a volume heat source. Nonlinear effect of temperature dependent thermal properties, latent heat and the convection and irradiative heat losses were considered. Numerical results of the temperature fields in the brazing joint were obtained for typical process parameters. The results show that, the temperature gradient of individual beam brazing is high. In dual laser beam brazing with 2mm spot distance, the peak temperature and temperature gradient are low and high-temperature zone is wide, which is benefit to achieve good brazing quality.

A strength model based on the particle-strengthening and age-strengthening mechanism and precipitation kinetics, was presented to examine the quantitative relationship between the particle sizes, volume fraction and the ageing parameters and the yield strengths of Al/SiCP composites. The model can be used to predict the variation of the yield strength of composites as the variation of volume fraction, size of reinforcements and aging time. the predicted values are consistent with experimental values when applying the model to 2xxx aluminum alloy reinforced with SiC particulates.

The magnetic attachment wrapped with 26-1 ultra-purified ferrite stainless steel can improve its corrosion resistance. The fibroblast L929 cells of mouse were treated in vitro through 3 kinds of leaching liquors of stainless steel to detect the apoptosis rate and cell cycle distribution of L929 by the flow cytometry PI staining method, and the morphology of cell apoptosis was observed by electron microscope. Compared with the Tilite alloy and Co-Cr alloy, the type of cell apoptosis was quantitatively determined by di-parameter technique in which the annexin was marked by the fluorescein isothiocyanate (FIT) and stained by the iodonadine. The result showed that 26-1 ferrite stainless steel can induce the apoptosis of L929 cells with a fashion of time-dependence, and the apoptosis rate depends on the concentration of the leaching liquor. It also proved that 26-1 ferrite stainless steel meets the biocompatibility as a clinical material and can be safely applied in clinic.