The microstructure evolution of large-grained FeAl intermetallic alloys during superplastic deformation has been investigated. The superplastic deformation exhibits characteristics of conventional grain-fining. During superplastic deformation, the shape of original grains changes significantly at first, then many subgrain boundaries form in the grains, and after that the misorientation of every two adjacent subgrains increases. In a whole,it results in the dramatical decrease of the grain size of FeAl alloys after the supefplastic deformation to fracture. The deformation activation energy was measured to be about 370,290 and 260 kJ. mo-1 for Fe-36.5Al, Fe-36.5Al-1Ti and Fe-36.5Al-2Ti alloys,respectively, which are much lower than the creep activation energy previously measured in FeAl alloys. Low deformation activation energy indicates that the superplastic deformation process may be controlled by subgrain boundary and grain boundary diffusion.

A three region model was proposed to study elasto-plastic mechanical behavior of two-phase composites by finite deformation FEM. The influences of two region model,three region model and periodic distribution particle model on the calculated results were compared. The effects of shape, distribution and volume fraction of inclusions on the elasto-plastic mechanical behavior were analyzed. The results obtained in this paper are important for understanding macro-behavior of two phase composites.

The spectrum of internal friction in a interstital free cold-rolled steel produced by Baoshan Iron and Steel Companay (BIF) for automobile has been studied. The results showed that a Snoek-Ke-Koster peak appears for in situ annealing steel at 900℃ and there are different influences of magnetic field on the internal friction in the specimens annealed at 700℃ and 720℃.

Laser gas alloying with nitrogen was employed to improve the wear resistance of TiAl intermetallic alloys. The rapidly solidified in situ wear resistant composite materials reinforced by hard TiN were successfully fabricated in the laser modified surface layer. The microstructure and properties of the laser modified surface are controllable by the laser processing parameters. Results of the research demonstrate preliminarily that laser gas alloying with nitrogen is a promising new surface modification technique for improving the wear resistance of TiAl intermetallic alloys.

Based on analysis to previous research on hot cracking of alloys, a hot cracking model formed through solidification contraction and compensation was proposed. In this model, solidification process of alloy was divided to four stages, quasi-liquid phase stage,compensated stage, uncompensated stage and dendritic bridging stage. Hot cracks started in uncompensated stage. The contraction of inter-dendritic liquid caused cavities between dendrites, then the dendritic bridges broken and hot cracks formed. Fraction range of liquid in uncompensated stage is calculated to be 0.83%-26% and 0.31-9.3% for alloys with equiaxial and columnar grains respectively. The temperature range of uncompensated stage for Al-Si and Al-Cu alloys was calculated. Comparison between theoretical calculation and hot cracking experiments showed that hot cracking tendency of alloys increases with the increase of temperature range of uncompensated stage. The dendritic bridges were first discovered in hot cracks of directionally solidified alloys. The tracks caused by dendritic bridges breaking were also discovered on the section of hot cracks.

Z form propagation of cracks in 22Mn- 13Cr-5Ni-0.2N steel has been investigated by means of in situ tensile test in TEM. The results show that the Z form propagation of a crack in the steel is formed by the alternate progress of the relative sliding of the {111}and the cleavage along {100}, and is determined by the relative orientation between outside force and crystal.

In the present study, a coupled mathematical model to describe the fluid flow and heat transfer in the tundish was developed. The three-dimensional flow and heat transfer in the one-strand tundish with and without flow control were numerically studied, and the functions of flow control devices in tundishes were discussed.

Atomic parameter-artificial neural network method has been applied to study the regularities of the mutual solubility, the consolute temperatures, and the composition of monotectic points of molten salt-liquid metal systems. It has been found that larger melt's is correspond to lower mutual solubility. Trained artifical neural can be used to predict the consolute tempertures and the composition of monotectic points of molten salt-liquid metal systems. The error of the results of computerized prediction is rather small.

The precipitating morphology of the boron components in the boron slags were in both crystallized and amorphous forms during the solidification of the molten salgs.The efficiency of extracted boron (EEB) from the former slag, crystal form, was obviously higher than that from the later slag. The precipitating behavior and morphology of the boron components in the slags can be artificially controlled. The Suanite(2MgO·B2O3) will exist as main phase by changing chemical composition, temperature of heat-treatment and addition,that is the selective precipitating. SEM in situ observation of the heating sample and the computer simulation combined with fractal description confirmed that the precipitating processes of the molten slags consists of the separation of amorphous phase through spinoda1 decomposition and of the precipitating of Suanite by the model of diffusion limited aggregation.

The smelting process in melting gasifier of COREX has been simulated experimentally. Using the way of dissecting the melting gasifier, reaction mechanism and rule of distribution of sulfur have been studied. The changing patterns of sulfur content in DRI, flux,coal, gas, slag and liquid iron, which effect on sulfur content of the metal, were obtained.

The isothermal oxidation behavior of Ti-33.3% Al, Ti-48% Al and Ti-52%Al(atomic fraction) intermetallic compounds oxidated at 1073 and 1173K in air was investigated. The reaction products of the oxidation scale were examined by XRD, and the surface morphology and cross-section microstructure of the oxidation scale were analyzed by SEM equipped with EDS. The results indicated that the oxidation scale of binary Ti-Al alloys was consisted of a series of thin layers, and the oxidation process could be classified into three steps, the growing direction of the oxidation scale and the rate-controlling factor of various steps is somewhat different; the isothermal oxidation kinetic curves mainly follow parabolic rate law.

Surface quality of continuously cast metals can be improved by imposing an intermittent high frequency magnetic field from the outside of a mold. The contacting state between a molten gallium, adopted as a simulator of a molten steel, and the mold was visualized by use of an optical fiberscope camera, the relationship between the intermittent contacting distance (representing contacting state), d, and intermittent frequency,f1 was investigated and the theoretical analysis of the melt motion under the intermittent magnetic field was conducted. Moreover, the molten tin was continuously cast under the conditions imposing intermittent and continuous magnetic field. It was found that when f1 is close to the intrinsic frequency of the experimental system, the intermittent contacting distance increases due to resonance motion of the molten metal. Under the condition of imposing intermittent magnetic fieId, the meniscus motion generated by mold oscillation can be effectively suppressed and electric current required to get the same surface quality is equal to 30%-50% of that of imposing continuous magnetic field.

The microstructures and textures during recrystallization process in the aluminium sheet which had been longitudinally and transversely rolled were investigated. The oriented growth during the recrystallization was directly observed by transmission electron microscope and the orientation relationships of new grains were determined by electron diffraction. The pole figures were measured with X-ray diffraction goniometer and ODF's were calculated by Bunge's method. The results showed that recrystallized grains with some oriented relationship to the deformation matrix grew more rapidly than others, which leads to the final texture. In fcc metal, this orientation relationship is about 40° <111>.

By introducing disordering energy Ed, an effective molecular field coefficient λ(T)as a function of thermal energy, the exchange interaction energy and disordering energy is proposed to intefpret spontaneous magnetization of ferromagnetic materials. Usingλ(T),the relationships betweem Tc, θp, and Ed / k and the relationships of (ρ/X)-T and (Ms,/M0)-(T/Tc)were derived. The results show that the curves of (ρ/X)-T and (Ms /M0)-(T/Tc)fit the experimental curves of Ni very well.

Debye temperature of nanometer-sized silver(n-Ag) particles was studied by the method of the double temperature X-ray diffraction. It was found that values of most specimens were higher than that of the bulk-Ag. And there existed a critical size.When the particle size was smaller than the critical value, the smaller the particle size was, the lower its became. To the specimen with larger particle size than the crucial size, its became smaller than that of the specimen with the crucial size.It was also deduced that the relation between and d of n-Ag particles could be given as:which explains the experiment result reasonably.

Si nanofiber was prepared by using arc plasma evaporation method. The experimental results revealed that one-dimension growth of the Si particle clusters was responsible for the "neck-connection" between the particle and its surface amorphous layer.Self-diffusion between the particles and surface diffusion on layer of the particle were carried on in various deposition temperature zones.

Mechanisms of heat affected zone (HAZ) liquation and liquation cracking in GH150 alloy were investigated by using varestraint test and hot ductility test in conjunction with the differential thermal analysis (DTA) and optical, scanning electron microsopy. On heating, γ/ (Nb,Ti)C liquation take places in the HAZ above 1250℃. When the temperature reaches 1353- 1375℃, a large amount of liquid particles due to initial melting can be observed within the grains near the fusion boundary. On cooling, γ/(Nb,Ti)C eutectic and γ/ Laves phase eutectic take place at 1273 and 1200℃ respectively. The constitutional liquation of (Nb, Ti)C particles on heating and γ/ Laves phase eutectic reaction on cooling are the main metallurgical factors responsible for the HAZ liquation cracking in GH 150 alloy.

TiO2 sol was prepared by hydrolysis and polycondensation of titania alkoxides in the presence of acetic acid. Further study focused on dipping TiO2 oxide coating on carbon fibers by sol-gel continous processing and fabrication of Cf/ Al preformed wire.Some characterization methods such as IR, TG-DTA, XRD, SEM are used. The results show that the effect of TiO2 coating depends on the viscosity of sol. After coating treatment,the cracks on carbon fiber surface are covered, oxidation resistance of carbon fibers is enhanced, the wettability between the fibers and melting aluminum is greatly improved and the tensile strength of C / Al prefabrication is heigtened.