Materials Science Forum Vol. 749

Abstract: In this work,Ti-V-based hydrogen storage alloys have been studied because of their high hydrogen absorption/desorption capacities and good activated properties. Experimental data of phase equlibria and thermodynamic assessments of the sub-binary/ternary systems in the Ti-V-based multi-component systems are reviewed in reported literature. Based on the measured phase diagram data and thermochemica information, thermodynamic parameters formulating the Gibbs energies of various phases in some sub-binary/ternary systems of Ti-V-based multi-component alloys are assessed using the CALPHAD method. A set-consistent thermodynamic database of the Ti-V-based multi-component system is developed, which is helpful to study the relations between alloy compositions, microstructure and hydrogen storage properties in order to design novel Ti-V-based hydrogen storage alloys.

Abstract: The Fe-Cr-Si-P amorphous powder with various La₂O₃ contents was cladded on 304L substrates by laser technology. The effects of La₂O₃ contents on microstructure and properties of the coatings were investigated. The results showed that the coating mainly consisted of amorphous, Fe₃P and Fe₂Si phases. A small amount of La₂O₃ addition could inhibit the epitaxial growth, and refine the dendrite crystals. When the content of La₂O₃ was 0.1%, the amorphous content of the coating was up to about 55%, and the maximum microhardness was about 900HV_0.2.

Abstract: With micron Al₉₀Mn₉Ce₁ alloy powder clad by TiO₂ nanopowder, a dense closed micro-cellular ceramics structure was fabricated. The alloy composite was filled inside by spark plasma sintering at temperature 793 K, and with the composite density of 98.2%. Micro-temperature area of Al₉₀Mn₉Ce₁/ TiO₂ matrix was simulated through ANSYS, and the macro lower temperature sintering mechanism was analyzed. The microstructure of the interface was investigated via scanning electron microscope, and the composition distribution of the interface was investigated via energy dispersive spectrometry. The formation and evolution of the interfaces were analyzed from plastic deformation, the interface creep, interfacial diffusion and other aspects. It was found that the application of DC pulse current has important effect on interfacial behavior and the performance of composite.

Abstract: With a brief introduction of self-propagating high-temperature synthesis (SHS) and lost foam casting (LFC), there goes an issue about the simultaneous produce of casting and wear-resistant coating by the combination of such two techniques, which has a positive significance for energy conservation and sustainable development. Through the statement of some common hard phases generated by SHS such as TiC, WC and TiB₂, it indicated that the hard phases had a good combination with iron, and thus demonstrated the feasibility of the simultaneous produce of casting and wear-resistant coating. In the end, the development and the trend of the future about this issue has been drawn.

Abstract: The formation Gibbs energy of the intermetallic phases at the interface of cold rolling Cu/Al clad metal sheet in annealing process was calculated theoretically. The concept and the calculating method of effective formation Gibbs energy which can predict the formation sequence was proposed. By the means of that theory, the calculated formation sequence of the intermetallic phases at 200-300 was worked out for the cold rolling Cu/Al clad metal sheet in annealing process, i.e. Al₂Cu (Al side), AlCu (mid-layer) and Al₄Cu₉(Cu side). Besides, the boundary layer organizational microstructure of the composite material was analyzed by the means of SEM and XRD. As a result, the annealing temperature is the primary factor which affects the formation of the intermetallic phases of the cold rolling Cu/Al clad metal sheet, while the holding time is the second one. The observed formation sequence of the intermetallic phases of cold rolling Cu/Al clad metal sheet on annealing temperature 250-300 was: Al₂Cu (Al side), Al₄Cu₉(Cu side) and AlCu (mid-side).

Abstract: Self-corrosion and galvanic corrosion of depleted uranium and 45 steel were studied by electrochemical analyzing technologies. Corrosion products were analyzed by Energy-dispersive spectroscopy (EDS). The results showed that, in the 3.5wt.%NaCl solution, DU acted as anode with an accelerated corrosion rate, and 45 steel acted as cathode during the process of galvanic corrosion for DU/45 couple. The galvanic potential and current density of the DU/45 couple were around-770mV and 12.5μA/cm^-2, respectively.

Abstract: The elastic buckling of a biaxially pre-tensioned soft elastic film in proximity to a rigid contactor was studied. By a linear analysis, it was shown that the critical mode of buckling depended on the two in-plane principal stretches in the respective tensile directions, and the threshold of buckling only depended on the product of two principal stretches. Such a regular effect of pre-tension may be applied in the field of the generation of the precise surface patterns.

Abstract: Thermal barrier coatings (TBCs) are very important ceramic coating materials due to their excellent performance at high temperature. Double-ceramic-layer (DCL) La₂Zr₂O₇ (LZ)/8YSZ TBCs, nanostructured single-ceramic-layer (SCL) 8YSZ and conventional SCL 8YSZ TBCs with the same thickness were fabricated by atmospheric plasma spraying in the present work. The static high temperature oxidation behaviour of the three as-sprayed coatings at 1000 and 1200 was investigated systematically. The results indicated that the LZ/8YSZ has higher oxidation resistance than that of SCL 8YSZ. The addition of LZ ceramic layer can increase the insulation temperature, impede the oxygen transferring to the bond coat and decrease the formation rate of the thermally grown oxide (TGO). The formation of the oxidized isolated islands in the bond-coat has decreased the effective thickness of the TGO at the bond coat/ceramic layer interface due to the depletion of the metallic elements in the bond-coat.

Abstract: Electrolysis expansion of carbon cathodes due to alkali metal penetration in [K₃AlF₆/Na₃AlF₆]-AlF₃-Al₂O₃ melts was tested. Effect of ampere density and superheating temperature on the electrolysis expansion was studied. A mathematical model was got to numerically describe electrolysis expansion performance of carbon cathode. The results indicated that K and Na penetrate into carbon cathode from outside to inside. Ampere density and superheating temperature had a great effect on the electrolysis expansion of carbon cathode. With the superheating temperature increasing from 10 to 50, electrolysis expansion increased from 1.41% to 2.10% gradually. With the ampere density increasing, the increase trend of electrolysis expansion was not linear. When ampere density was lower than 0.4A / cm² and greater than 0.7A / cm², cathode electrolysis expansion obviously increased with the increase of ampere density. Meanwhile, cathode electrolysis expansion tended to be constant as the ampere density changed at the range of 0.4A / cm² to 0.7A / cm².The results of the mathematical model in this study had a good agreement with the test results. This model would be helpful to accurately describe the anti-penetration performance of K and Na on the carbon cathode.

Abstract: Ti-6Al-4V films were deposited by direct-current magnetron sputtering at different substrate temperatures. The structure and the surface morphology of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hardness and elastic moduli of Ti-6Al-4V films were measured by nanoindentation test. The results showed that the phase direction of the films deposited at room temperature was (102) orientation, and turned to almost complete (002) preferred orientation at 300°C. For a higher temperature of 500°C, the preferred orientation of the film disappeared and presented a random grain orientation. The hardness and elastic moduli of Ti-6Al-4V films obviously showed the dependence on the temperature. The relationships among temperature, microstructure and mechanical properties of Ti-6Al-4V films were discussed in this paper.