Deoxidation experiments using improved deoxidation unit are carried out in 20 kg induction furnace. Experimental results prove that deoxidization process is fast and effective. But the oxygen in melt can not be decreased below 20X10-6 because oxygen in melt is recovered by some experimental conditions such as existing oxidizing slag and refractory or closed experimental system was destroyed while measuring oxygen in melts and replacing deoxidation unit.

Ti--Zr--Ni alloy rods along two e/a--constant lines (e/a=1.20, 1.25) were prepared by using suction--casting method, the systematic investigation on these as-cast alloys shows that Ti--Zr--Ni quasicrystals are formed over a large range of composition, (TixZr100-x)100-yNiy (43.75% References | Related Articles | Metrics

Undercooled solidification of Al50Si50 (atomic fraction) melt is achieved by repeatedly heating and cooling in electromagnetic levitation facility. A maximum undercooling of 320 K is obtained. Phase morphologies on surfaces and deeply etched sections of the samples solidified at different undercoolings are examined. The primary silicon shows faceted dendrites with stratified deposits of aluminum at small undercooling, but shows granular form without deposits of aluminum at large undercooling. The form of the Al--Si eutectic is also found changed into anomalous form at large undercoolings. The microstructural refinement is observed at large undercooling, as a result of solute restriction of crystal growth and fragmentation of the primary silicon dendrites.

The structures of 14 molten Fe--Si alloys were studied at 1550℃ by a theta--theta X--ray diffractometor. The alloys with a composition interval of about 10%Si (atomic fraction) including some intermetallic compounds. The analysis on the experimental data employed the following parameters: the height, position and half--width of the first peak of the structure factor, the first peak position of the pair correlation function, the first peak shape of the radial distribution function and the coordination number etc.. The results show that the structure behavior of molten Fe--Si alloys along the whole composition range could be divided into four intervals which are indicated by 5 borders of Fe, Fe0.754Si0.246, Fe0.50Si0.50, Fe0.282Si0.718 and pure Si. Distinct structural change was observed across the borders. The liquid structure of Fe0.50Si0.50 alloy inherited the structure of intermetallic compound FeSi to some extent. Covalent bonding between Si--Si atoms was speculated to exist in alloys with Si content higher than 50.0%. Furthermore, the existence of prepeak in the structure factors of some Fe--Si alloys marked the medium--range order in such alloys. Some models and results by other researchers were also discussed.

The effects of the fluxes containing LaCl$_{3}$ on the mechanical properties, structure, fractography and corrosion behavior of magnesium alloy have been measured. The results show that small and nodular Al$_{10}$La$_{2}$Mn$_{7}$ phases can be formed in melts after fluxes containing LaCl$_{3}$ was added to Mg melt which can act as nucleating site of $\gamma$ phases, making the $\gamma$ phases refined. The tensile strength $\sigma_{\rm b}$ and elongation $\delta$ can be improved by addition of LaCl$_{3}$. Using fluxes containing 5\% LaCl$_{3}$, the $\sigma_{\rm b}$ and $\delta$ of the alloy can be improved from 161 MPa and 2.1\% to 203 MPa and 4.0\%, respectively. That is, the $\sigma_{\rm b}$ and $\delta$ increased by 26\% and 100\%, respectively. Increasing the content of LaCl$_{3}$ further, the fluxes will agglomerate during the refinement process, so that the inclusions in the melt will increase and the mechanical properties of Mg alloys decrease. The fracture mechanism of quasincleavage of Mg alloy has not been changed by LaCl$_{3}$, The corrosion test results show that LaCl$_{3}$ can improve obviously the corrosion resistance of Mg alloy. The corrosion rate of magnesium alloys can decrease from 1.10 mg/(cm$^{2}\cdot$d) to 0.17 mg/(cm$^{2}\cdot$d) in 5\%NaCl solution by using fluxes containing 5\% LaCl$_{3}$. That is, the corrosion rate can be decreased by 84\%.

Columnar grain Al samples with 001uv0 orientations were cold rolled to reductions of 10%, 30% and 50%, respectively. The macroscopic subdivision of grains with different orientations was characterized in detail by using EBSP technique. It is found that the macroscopic subdivision patterns of different oriented grains are different. A model based on dislocation slip was used to analyze the observed macroscopic subdivision patterns.

Columnar grain Al samples with 001uv0 orientations were cold rolled to reductions of 10%, 30% and 50%, respectively. The microscopic subdivision of the matrix bands in grains with different orientations was quantitatively characterized in detail by using EBSP technique. It is found that all the grains are microscopically subdivided into dislocation cell blocks. But the microstructures of differently oriented grains are different after rolling. With increasing strain, the misorientation angles across the dislocation boundaries increase, following a power relationship with an exponent of 2/3. By the Frank formula, the dislocations in the dislocation boundaries are mainly from the slip systems decided by the Schmid factors.

Using X--ray tensile test, the relationship between the yield strength and annealing temperature for a Cu film with biaxial residual stress adherent to substrate was investigated. The results indicate that the proof stress of the film decreases with increasing annealing temperature. When annealing temperature rose from 150℃ to 300℃, the decreasing amplitude of proof stress is the largest. The reason of this phenomenon is that recrystallization in film occurred at 300℃, and a majority of structure strengthening effects disappeared. The yield strength of the Cu film on the steel substrate is greatly higher than that of block Cu.

The effect of deformation on the stress-induced martensitic transformation behavior of the Ti44Ni47Nb9 alloy was studied by DSC and cryogenic tensile tests at Ms+30℃. DSC measurements show that the process of stress--induced martensitic transformation is completed as the tensile strain reaches to about 14%, and the transformation is inhomogeneous microscopically. The reverse transformation temperature interval of the stress--induced martensite was found to be much smaller than that of the thermally induced martensite. The experimental results also indicate that A's temperature of the first reverse transformation, its temperature interval and transformation heat are all increased with increasing the level of deformation. However, the wide hysteresis effect due to the deformation vanished after the first heating. The transformation heat in the subsequent transformation cycle, the forward transformation start temperature of the first cooling and the reverse transformation start temperature of the second heating are all decreased slightly with increasing deformation.

Ceramic particles of SiC (10%) or TiB2 (15%) (volume fraction) were added in the Mg65Cu20Zn5Y10 bulk metallic glass forming alloy to form the bulk metallic glass composites using copper mold casting. The introduced particles have no adverse effect on the glass forming ability of the matrix alloy. The second phase ceramic particles uniformly disperse in the glass matrix. Uniaxial compressive strength of the composites reached about 1 GPa, a factor of 1.2 higher than the Mg65Cu20Zn5Y10 monolithic glass. The failure for the Mg65Cu20Zn5Y10 monolithic glass occurs at a stage of elastic strain without any visible plastic strain before the fracture. In contrast, a plastic strain to failure about 0.9% was obtained for the TiB2 particulate reinforced composite.

Molecular dynamics (MD) simulations were used to study the diffusion activities of Cu atoms in supercooled state and amorphous state. The embedded atomic (EAM) potential was selected as many--body interaction. Using the mean square displacement (MSD), the diffusion properties of Cu atoms were investigated during relaxation. The transformations of microstructure feature were pursued by means of pair correlation function and pair analysis technique. The calculated results indicate that the diffusion of atoms plays an important role on the crystallization of liquid and amorphous Cu.

Based on the embedded--atom method, a constant--pressure, constant--temperature (NPT) molecular dynamics (MD) technique is applied to obtain an atomic description of glass formation process in eutectic Cu40Ag60 alloy. By using radial distribution function (RDF) and pair analysis (PA) methods, the structure and glass forming ability of this alloy is studied by quenching from the liquid at different cooling rates. It is observed that the retention of amorphous structure requires extremely high cooling rates. Structure analyses of the alloys in the simulations reveal the evolvement of the different clusters at various quenching rates.

The primary crystallization of binary system was simulated by the Monte--Carlo method. The crystallized phase radius is a linear relationship with the square root of the time, which corresponds exactly with academic formula. The simulated results of the primary crystallization patterns show that the crystallized aggregation degree has a good relativity with the diffusion parameter, and nucleation parameters, while the growth parameter affects the circinal degree strongly.

(Ti,Al)N coatings with interlayers were deposited on SiCp/2024Al composites by arc ion plating at different negative bias voltages. The phase constitution, lattice constant and the composition of the coatings prepared at different negative bias voltages were analyzed. It is shown that (Ti, Al)N coatings have preferred orientation changed from (111) to (200) and (220) with increasing of negative bias voltage. The coating with Ti interlayer exhibits well adherence to the substrate compared with TiAl interlayer. To gain thick coating with 105 um, the (Ti, Al)N coating with a gradient nitrogen component was designed.

The electrochemical behaviors of the zinc--rich paints based multilayer organic coatings in 3.5% NaCl solution were studied. The results show that the zinc powder has a minor cathodic protection effect. The protection effect is due to the repair of holes by the corrosion product of zinc powder. Under the epoxy topcoat, the corrosion rate of the zinc powder in inorganic zinc--rich coatings is faster than that in organic type.

LY12CZ alloy samples with different exfoliation corrosion grades were prepared by dipping in EXCO solution. EIS characteristic of samples in 0.1 mol/L NaCl solution was studied. The results show that the samples with different exfoliation corrosion grades in 0.1 mol/L NaCl solution are of different EIS characteristic which can be used to distinguish the exfoliation corrosion state. The results provide a necessary foundation for field-monitor of aluminum alloy exfoliation corrosion.

The potential--time curve of anodic dissolution of tinplate by constant--current electrolysis in hydrochloric acid solution with relatively high current density has been used as a tool for the characterization of corrosion resistance of tinplate products. Three pattern recognition methods, including SVM (support vector machine), PCA (principal component analysis) and Fisher method have been used for modeling the relationship between E--t curve and ATC (alloy--tin couple) values describing the corrosion resistance of tinplate samples. The obvious correlation between E--t curves and ATC values implies that it may be possible to find a quick method useful for monitoring and optimal control of the quality of tinplate in industrial production.

Stress corrosion cracking (SCC) of a sensitized 304L stainless steel was carried out under slow tension of a pre--cracked sample in water containing oxygen at 288℃. Thin foil samples were prepared along its cross--section containing the pre--cracks, and the tip region of SCC was studied by analytical TEM. The observations show that there are oxides with a size of several hundreds nanometers ahead of a crack tip of SCC and around the discontinuous microcracks. Fine--probe analysis was used to determine local compositions of the oxides, indicating the oxides are Cr2O3, Fe3O4 and their mixture. Many microcracks are distributed unevenly in the oxides. Microcracks initiated discontinuously in the oxides ahead of a main crack because of a large stress concentration. The growth and connection of the discontinuous microcracks in the oxides resulted in the propagation of SCC.

The effects of ultrafine--enamel coating on the isothermal oxidation behavior of Ti60 alloy at 800℃ and the diffusion behavior of oxygen into the substrate at 600℃ are studied. The results show that the enamel coating could improve the oxidation resistance of Ti60 alloy at 800℃ significantly due to its high thermal chemical stability and good match of its thermal expansion coefficient with the substrate. At the same time, the ultrafine enamel frit (300 nm) could be sintered at 850℃ which was decreased 200℃ compared to the general enamel frit (20 um) with the same components. The dense and uniform coating could separate the Ti60 alloy from environment and decrease the diffusion rate of oxygen in the coating.

The high temperature hot corrosion behavior of the (Ni, Pd)Al coating coated with Na2SO4 or Na2SO4+25%NaCl at 900℃ was investigated by TGA, XRD, SEM/EDS. Results show that (Ni, Pd)Al coating has higher oxidation resistance than the NiAl coating. The modified element Pd incorporating into the aluminide coating hinders the diffusion of S into the inner part of the coating matrix, and increases the hot corrosion resistance of the aluminide coating.

A 3D finite element method is used to the simulation of cold pilgering process of 1Cr18Ni9Ti stainless steel tubes by using ANSYS software, which are cast by electromagnetic centrifugal casting (EMCC) and of the characteristic of composite structure. Simulation results show that during cold pilgering the better the axial plasticity of tubes, the smaller the shear stress $\sigma_{\rm rz}$ and the shear strain $\varepsilon_{\rm rz}$, as well as the better the property of rolling deformation. Along with the decrease of the Coulomb friction coefficient not only the $\sigma_{\rm rz}$ and the $\varepsilon_{\rm rz}$ are decreased, but also the discontinuity of $\sigma_{\rm rz}$ between outer columnar and inner equiaxied zone is decreased. Moreover, the property of rolling deformation and the quality of tubes are improved. With the increase of exciting currents, which enlarges equiaxed zone, not only the mechanical property of the tubes is improved, but also the $\sigma_{\rm rz}$ and the $\varepsilon_{\rm rz}$ are decreased. Moreover, the property of rolling deformation and the quality of tubes are also improved. The simulation results agree well with the experiment.