Equal--channel angular pressed (ECAP) Al--Li--Cu--Mg--Zr alloy mainly consists of near equi--axial grains with size smaller than 1 m. ECAP Al--Li--Cu--Mg--Zr alloy cyclically softens continuously to failure at higher strain amplitude of p/2=5.510 -3, but cyclically softens initially and then harden continuously to failure at lower strain amplitudes of p/2=510 -4---2.610 -3. The Coffin--Manson curve of the ECAP Al--Li--Cu--Mg--Zr alloy shows an ideal straight line. All these properties are different from those reported previously for the conventional peak--aged Al--Li--Cu--Mg--Zr alloy.

The electric fatigue property and fatigue mechanism of PLZT ferroelectric ceramics were studied. The dielectric constant and hysteresis loops for the non--fatigued sample were measured and compared with those for the fatigued sample at room temperature and with those for the fatigued sample annealed above the Curie temperature for hours. The experimental results show that the temperature dependences of dielectric constant and the hysteresis loops of the fatigued sample annealed above the Curie temperature for hours differ significantly from those of the non--fatigued sample.The SEM analysis indicates that the facture mode is mainly trans--granular for the non—fatigued sample, while inter--granular for the fatigue sample. The magnitude of strain due to the 90.domain reorientation during the application of an AC electric field, estimated from the in--situ XRD spectra, reaches as high as 0.1%. This repeated and high strain induced by the 90 domain reorientations ultimately leads to electric fatigue of the samples.

Cyclic testes were conducted on commercially pure titanium with low hydrogen concentration, in which  hydrides dispersed homogenously. It was found that dislocations can transfer through the coherent interface only before the hydride was fragmented, after fragmentation, dislocations would tangle at the fragments and do not penetrate the interface again due to the decrease of the maximum stress in the fragments. At least three sets of dislocations can be activated in hydrides during the cyclic deformation. To accommodate the inhomogenous strain between the matrix and hydrides, the crystal rotation occurred in both of them. A mechanism for the crystal rotation has been proposed.

Cyclic testes were conducted on commercially pure titanium with low hydrogen concentration, in which  hydrides dispersed homogenously. It was found that dislocations can transfer through the coherent interface and result in the plastic shear deformation of  hydrides. Because hydrogen atmosphere around dislocations can be dragged and move along with the dislocations, so hydrogen atoms diffuse preferentially along the slip bands. The process of slip band transferring through the hydrides accompanies the diffusion of hydrogen atoms along slip bands.The preexisting hydride may dissolve under the impingement of slip bands, due to the decrease of the localized hydrogen concentration. Also the dislocations with the hydrogen atmosphere may pile up at the hydride interface, and hence result in the increase of the hydrogen concentration, then strain induced hydrides would appear. The reversible transformation is considered to be diffusion--controlled and influenced by dislocations movement.

The influence of Ca and Na on phosphorus modification performance, the relation between constitution of compounds containing--phosphorus and modification performance in eutectic Al--Si piston alloys were investigated by optical microscopy and electron probe microanalyzers (EPMA). It has been shown that Ca or (and) Na can make phosphorus modification inefficiency and even Na modification efficiency appears, the abnormal phenomena is due to the formation of (Ca n-x, Na x)P m compounds which is more stable than AlP phases in the melt. However, the phosphorus modification efficiency can recover after refining treatment by C 2 Cl 6, because of (Ca n-x, Na x)P changing to (Al 5, Mg 0.85, Ca 0.15) P 3.4which can serve as the nuclei of primary Si phases.

The structure and energy of the system formed by 500 Cu—atoms controlled by the period boundary condition have been studied by the molecular dynamics simulation in the melting and solidification process, in which the FS potential was used. The conclusion obtained is that the melting point of Cu is 1444 K at continuous heating process, the crystallized point is 1014 K at slower cooling rate and the non--crystalline phase will be formed at faster cooling rate. In the end, the influence of the temperature changing rate has been analyzed from a view of the total energy changing, and the relationship between the microstructure and the system total energy has been pointed out.

Based on an advanced neural network method and a huge number of creep rupture life data of nickel base single crystal superalloys, an artificial neural network model is constructed to predict creep rupture life for different types of nickel-base single crystal superalloys. The results indicate that the creep rupture lives can be more accurately predicted with this method for different generations of nickel-base single crystal superalloys. Combined with neural network prediction, the orthogonal analysis method is used to reveal the influence of alloying elements on creep rupture life of the single crystal superalloys with the given composition under 982℃/250 MPa.

The plane strain compressive deformation experiments with various deformation amounts have been carried out on the grain boundary allotriomorphic ferrite/granular bainite F GBA/G Bduplex steel at temperatures above A r3 using Gleeble--1500 machine. SEM and TEM observations indicate that the prior austenite deformation not only refines the allotriomorphic ferrite grain but also promotes the nucleation of intragranular ferrite, both of which in turn contribute to the refinement of granular bainite cluster including its ferrite platelets and MA islands. A model was proposed to elucidate the effect of prior deformation on the refinement of granular bainite cluster and its detailed microstructure. For specimens deformed by 30% at 780℃ and subsequent air cooling, F GBA grains of an average size less than 5 m and intragranular ferrite grains less than 3 m were gained. Compared with specimens without prior deformation, the Charpy V--notch (CVN) impact energy and Vickers hardness is increase from 43 J to 108 J and from 242 to 312, respectively.

The plane strain compressive deformation experiments with various deformation amounts have been carried out on the grain boundary allotriomorphic ferrite/granular bainite F GBA/G Bduplex steel at temperatures above A r3 using Gleeble--1500 machine. SEM and TEM observations indicate that the prior austenite deformation not only refines the allotriomorphic ferrite grain but also promotes the nucleation of intragranular ferrite, both of which in turn contribute to the refinement of granular bainite cluster including its ferrite platelets and MA islands. A model was proposed to elucidate the effect of prior deformation on the refinement of granular bainite cluster and its detailed microstructure. For specimens deformed by 30% at 780℃ and subsequent air cooling, F GBA grains of an average size less than 5 m and intragranular ferrite grains less than 3 m were gained. Compared with specimens without prior deformation, the Charpy V--notch (CVN) impact energy and Vickers hardness is increase from 43 J to 108 J and from 242 to 312, respectively.

Studies on behavior of platinum--group metals(PGMs) in pressure cyanide leaching indicate that the percent PGM extraction follows the order of Pd >Pt >Rh, while the chemical stability of PGM cyanide complexes at high temperature is RhPt > Pd. The leaching behavior of PGMs could be described by their chemical reaction activity of surface state, and is the synergetic influence of metal—bond strength and atomic--state stability. The high temperature stability of PGM cyanide complexes could be explained from the heavy platinum--group complexes having higher thermodynamic stability and kinetic inertia than light platinum--group complexes with same structure, and from the difference of chemical reaction activity of PGM cyanide complex ions.

A macrosegregation model, based on the continuum formulation, is developed to evaluate momentum, heat and mass transfers during electromagnetic centrifugal solidification. Using a non--inertial coordinate system, the model is applied to predict Al--5%Cu alloy solidification under electromagnetic centrifugal solidification. The results show that the effect of electromagnetic force on melt lowers the radial component velocity of melt flow. The change of melt flow decreases the inverse segregation at outer position of the solidifying alloy and the negative segregation at the mushy zone. Electromagnetic centrifugal solidification lessens marcogregation compared with conventional centrifugal casting. Good agreement is found between the simulation and experiment results, which shows the electromagnetic centrifugal solidification can be described well by this model.

A macrosegregation model, based on the continuum formulation, is developed to evaluate momentum, heat and mass transfers during electromagnetic centrifugal solidification. Using a non--inertial coordinate system, the model is applied to predict Al--5%Cu alloy solidification under electromagnetic centrifugal solidification. The results show that the effect of electromagnetic force on melt lowers the radial component velocity of melt flow. The change of melt flow decreases the inverse segregation at outer position of the solidifying alloy and the negative segregation at the mushy zone. Electromagnetic centrifugal solidification lessens marcogregation compared with conventional centrifugal casting. Good agreement is found between the simulation and experiment results, which shows the electromagnetic centrifugal solidification can be described well by this model.

Traditional solidification square root law is not fit for describing solidification process of round bloom and square bloom. A new solidification formula of round bloom, was deduced, which is also fit for the solidification process of square bloom, so it is called solidification law of round and square blooms. The correctness of the above formula was verified by the experiment result.

Nickel based superalloys with high content of tungsten (W) have been applied to cast the large size die. Because the formation of large amount of primary M 6 C phase embrittles the die, it is necessary to explore the forming condition of primary M 6 C. The experiments prove that the alloys containing carbon content higher than 0.15% (mass fraction) tend to precipitate primary M 6 Ccarbide and 10% Co can restrict the formation of M 6 C effectively. The primary M 6 C forms at 1375℃. The cooling rate between the solid and liquid temperature range can influence the precipitation of this phase sensitively. Rapid cooling retard the formation of M 6 C obviously. The section size effect of the formation of M 6 C exists in castings. For a heavy section possessing dendrite spacing higher than 150m, it is very easy to form M 6 C with a millimeter magnitude, which damages the high temperature strength of alloys. To prevent the precipitation of M 6 C in large size section die, the composition of alloy is recommended to maintain at the level of 0.04%---0.07% C and 10%---15% Co.

The hydride formed in hydrogen charging TiNi shape memory alloy could decrease evidently fracture toughness K IC of the TiNi alloy and the relative loss of K IC is as high as 96%. The relative loss of K IC induced by the hydrogen induced martensite, however, is only about 1.8%, and does not change evidently with hydrogen concentration. Therefore, the decrease in fracture toughness of hydrogenated specimen is almost completely attributed to hydride. The relative loss of induced by hydrides, increases with increasing hydride content. Microcracks could be generated along the hydrides during charging at i>15 mA/cm2 and do not cause farther the decrease in K IC .

The main ideas of component and structure designing for novel high strength and toughness Mn--Si--Cr bainitic steel are presented.Microstructure, delayed fracture mechanism and fatigue property have been analysis based on the excellent mechanical properties. The improvement in strength and toughness can be contributed to distinctive microstructure of duplex steel. The bainitic carbide is replaced by retained austenite film, which exhibits a better mechanical stability, thermal stability and chemical stability. The film also acts as a hydrogen trap, inhibiting crack propagation, and lower the susceptibility to hydrogen embrittlement.

A new Nd61Fe30Zn9 bulk metallic glass with a diameter of 2.5 mm was obtained using copper mold casting. No glass transition temperature or supercooled liquid region was observed by using conventional DSC--7 facility. The crystallization temperature for the bulk sample is 730 K, which is about 70 K lower than that of Nd60Fe30Al10 bulk metallic glass. The melting characteristics of Nd61Fe30Zn9 alloy show that its compositional is at a eutectic point, but the alloys exhibit non--eutectic microstructure due to high tendency of undercooled ability.

Thermodynamics of irreversible process offers linear expressions among physical quantities when there are physical--chemistry changes in the systems close to equilibrium, which has been extended to the systems far from equilibrium, and a uniform nonlinear chemical reaction rate equation was established to describe chemical reaction rate, that is in general far from equilibrium in discontinuous system, in which exist interface and chemical reactions. Finally, it was applied to manganese oxide reduction reaction and obtained a third--order expression, which well conforms to the experimental data. The thermodynamics of irreversible process after considering the high--order term can be applied to slag—metal reacting systems far from equilibrium.

Thermodynamics of irreversible process offers linear expressions among physical quantities when there are physical--chemistry changes in the systems close to equilibrium, which has been extended to the systems far from equilibrium, and a uniform nonlinear chemical reaction rate equation was established to describe chemical reaction rate, that is in general far from equilibrium in discontinuous system, in which exist interface and chemical reactions. Finally, it was applied to manganese oxide reduction reaction and obtained a third--order expression, which well conforms to the experimental data. The thermodynamics of irreversible process after considering the high--order term can be applied to slag—metal reacting systems far from equilibrium.

The internal oxidation technology of Al in Cu--Al pre—alloyed powders is discussed. The results show that the reacting temperature is a key factor to determine the critical oxygen partial pressure. The maximum oxygen partial pressure increases with increasing temperature, so that a little higher temperature than that of ordinary reaction is helpful to reduce the difficulty of controlling internal oxidation. High energy milling has little influence on the internal oxidation thermodynamics, however, remarkable influence on the internal oxidation kinetics. When the Al content exceeds 0.5\%, the heating parameters should be alternated based on Al content. It can be observed from the examinations of the samples that the spherical Al2O3particles with an average diameter size of 2---5 m and particles spacing of 5---10 m are dispersed in the Cu matrix uniformly, when used the suitable processing parameters of internal oxidation.

The ferrite and austenite stainless steels containing a suitable amount of Cu may be of antibacterial ability after a special antibacterial treatment. The distribution and appearance of the precipitates appeared in the Cu--contained stainless steels were studied with TEM. The results of antibacterial examination show that Cu--contained ferrite and austenite stainless steels have broad--spectrum antibacterial properties. By using bio--TEM, a obvious change of the bacterium appearance on the surface of antibacterial stainless steel is observed and a lot of bacteria enchyma leaks out.

A three--dimensional figure of normal stress and shear stress of one stress state was given, and the corresponding relationship of the figure with deformation type was analyzed.The figures can be divided into three main types, which refer to compression, plain strain, and tension, respectively. In addition, the stress--strain of typical points in simple tension, drawing, and extrusion was successfully analyzed by the figures.

Based on N--S function, continuity function, function of Fourier heat conduction and experiments, a mathematical model of mold filling and solidification in vertical centrifugal casting is presented by taking centrifugal force, gravity and Coriolis force into consideration. This model is further applied to numerical simulation of temperature field, flow field and pressure field of vertical centrifugal casting process of exhaust valve made of TiAl base alloy. The result of numerical simulation shows that the mold filling of vertical centrifugal casting consists of forward--direction filling and back--direction filling. Gas--holes defect easily appears at the entrance of valve. The two orders also exist in solidification proces and are major reason for formation of off—axis shrinkage nearby the side of filling first.

The amorphous Ni--S--Co alloy was obtained by electrodeposition method, and the effect of the current density on its structure and the contents of S and Co were measured. The tested results on the electrochemical properties show that the hydrogen evolution reaction overpotential of amorphous Ni--S--Co is only 70 mV and its electrochemical activity is much higher than other electrodes including amorphous Ni--S electrode. Furthermore, the corresponding electrochemical parameters, i.e. the Tafel slope, the exchange current density and the activation energy ,were obtained. The electrochemical stability of amorphous Ni--S--Co alloy is determined to be higher than that of amorphous Ni—S alloy. The high electrochemical activity and stability of amorphous Ni--S--Co electrode is also determined by the long--term electrolysis under the industrial conditions.