Materials Science Forum Vols. 561-565

Abstract: To comprehensive utilize the large amount of solid wastes from the production process, Iron making plant gradually increases solid wastes proportion in blended material for sinter by a series of process improvement and equipment upgrading. These approaches optimize technology index of blended material and provide refined material for blast furnace. Thus it creates considerable economic and social benefits the environmental via economizing the resources and reducing the environmental burden.

Abstract: Recent trends in bio technology have resulted in the need for accurate fabrication of pore structure of sophisticated porous materials used in advanced applications such as substrates for tissue growth, and various kinds of implants. Control of pore size is important for promoting growth of blood vessels and adequate fluid flow. In the present study, an attempt has been made to fabricate functionally porous structures using titanium, including an internally controlled three-dimensional (3-D) fractal structure. A novel 3-D modeling method that combines rapid prototyping with spark plasma sintering (SPS) is proposed, which enables us to control the internal porous structure. Titanium powder-tape or sheet is sintered or cut by a pulsed Nd:YAG laser to form 2-D fractal cross-sections. These 2-D layers are temporarily laminated in a carbon mold, being then jointed by the SPS method to maintain the internal porous structure. Process parameters for the sheet lamination method have extensively been investigated.

Abstract: Lightweight aluminum foams are attractive energy absorbing material for automotive machines. Strength of aluminum foams manufactured through casting process is not so much high as dense aluminum alloys due to difficult alloying. Ductility of aluminum foams manufactured through powder metallurgical process is low due to fine oxide dispersions. In this paper, we introduce new metallic foam having excellent energy absorbing property. Closed-cell Zn-22 mass%Al eutectoid alloy foams are manufactured through powder metallurgical process. The Zn-22Al alloy is known as typical superplastic material and shows superplastic deformation below 523 K, even at room temperature. Using titanium hydride powder as a foaming agent, the porosity as high as 60% is achieved. Solution treatment followed by quenching causes ductile compressive deformation at room temperature. In addition, the absorbed energy of the Zn-22Al foams are much larger than those of conventional aluminum foams.

Abstract: Char derived from pyrolysis of physic nut waste at 400-800°C was used for the preparation of activated carbon by chemical impregnation of phosphoric acid and potassium hydroxide. The original char exhibited the BET surface area in the range of 120-250 m2·g-1. The surface area increased to 480 and 532 m2·g-1 when activated with H3PO4 and KOH, respectively. Equilibrium adsorption data was found to be best represented by the Langmuir isotherm with maximum monolayer adsorption capacity of 560.13 mg·g-1 at 30°C. The adsorption capacity of the physic nut residue activated carbon was comparable to commercial activated carbon.

Abstract: Mechanisms of degradation of physical-mechanical properties of PVI steels during irradiation are studied. Microstructure evidence of influence of irradiation temperature, dose and dose rate on processes of low-temperature swelling and embritllement of pressure vessel internal materials, 18Cr-10Ni-Ti steel, of reactor WWER 1000 are presented. Micro mechanisms of plastic deformation and steel failure in wide range of temperatures and irradiation doses are described. Analysis of influence of subsequent and simultaneous irradiation with beams of gas and heavy ions is carried out for investigation of influence of gaseous impurities that form through transmutation nuclear reactions on defected structure evolution under irradiation.

Abstract: The formation process of intermetallic compound under Ni+ion implantation into pure Al was studied at lower temperature below room temperature. Ion implantation was carried out using 250KeV ion accelerator. Cascade damage was introduced Ni+ions implantation at 223K without new phase nucleation. However, when Ni+ions were implanted at room temperature, the grown larger plate-like phases were observed during implantation up to 1x1017 Ni+/cm2. Ni concentration in Al matrix and newly formed phase were 0.3-0.5 and 8.5-13.3at%,respectively. It was identified that the formed phases were close to the ordered orthorhombic structure of Al3Ni type. It was also confirmed from observation with high resolution HVEM that these phases grew with continuous ion implantation. Thus it was clarified that cascades act as preferential nucleation site for intermetallic compound, and the phases nucleated at cascades coalesce in the growth process of each phase during continuous implantation through ion irradiation enhanced diffusion.

Abstract: The Uranium Extraction (UREX) family of processes uses solvent extraction techniques designed to partition spent uranium and transuranic (TRU) isotopes from fission product waste. Once separated, the collective TRU elements (Np, Pu, Am, and Cm) can be recycled in advanced nuclear energy systems. A zirconium matrix cermet is proposed as a fuel form for this application. Processing methods have been designed to convert the TRU product and spent Zircaloy cladding into feed materials for the hot extrusion of the cermet fuel pins. The TRU conversion process is being developed using a surrogate mixture of uranium and cerium nitrate solutions to generate mixed oxide microspheres. The Zircaloy recovery process is a hydride-dehydride method that is being demonstrated at the bench scale. The powder products from these methods may be combined through hot extrusion into a cermet composite; demonstration experiments using zirconium powder and zirconia microspheres have been completed.

Abstract: We have explored irradiation effects on metallic glasses by using 140 keV He ions. The mechanical properties of nanostructured metallic glass are studied by using microindentation. The study shows the feasibility of developing a high strength alloy by ion irradiation of metallic glasses.

Abstract: China Low Activation Martensitic steel (CLAM), which is one of the RAFMs (Reduced Activation Ferritic/Martensitic steels) and under development in ASIPP, is considered as the primary candidate structural material and LiPb eutectic as both tritium breeder and coolant of the blankets in FDS series fusion reactors. The corrosion behavior of CLAM steel exposed to the liquid breeder LiPb is of significance. Corrosion tests of CLAM in flowing LiPb at 480°C were performed up to about 2000 hrs to analyze the corrosion mechanism of CLAM exposed to liquid LiPb. The specimens were observed and analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) after 500hrs, 1000hrs and 2000hrs corrosion experiment respectively. The corrosion is of non-uniform and the weight loss was about 0.23 mg/cm2 after 2000 hrs’ exposure, which is smaller for CLAM compared to those of other RAFMs.

Abstract: Ferritic heat-resistant steel comprises basic alloys of Fe-10mass%Cr-W. This study investigates how stress, the addition of Co, and tempering before aging affect the precipitation of the Laves phase of Fe-10Cr-6W ferritic heat-resistant steel, which is used in ultra-supercritical power plants and nuclear reactor materials. The study also investigates the mechanical properties of the steel. Precipitation of the Laves phase by aging increases the tensile strength, but decreases the elongation and impact strength of the alloys. Toughness of the alloys decreases greatly as very fine disk-like Laves phases appear in early aging stage. The strength and impact value of the steel decrease when the steel is tempered before aging. This is mainly due to decrease of density and increase of the particle size in the Laves phase. Since precipitation of the Laves phase increases by addition of Co; the strength increases and the elongation and impact value decrease.