The structural and thermodynamic properties of the non-oxide superconductor ZnNNi₃ are investigated by using ab initio plane-wave pseudo potential density functional theory method within the generalized gradient approximation (GGA). The calculated lattice constants, the bulk modulus and its pressure derivative, and elastic constants of ZnNNi₃ at zero temperature and pressure are in good agreement with the available theoretical and experimental data. The thermodynamic properties of ZnNNi₃ are predicted by using the quasi-harmonic Debye model. The pressure-volume-temperature (P-V-T) relationship, the bulk modulus B₀ and bulk modulus B, the variations of the thermal expansion coefficient α and the heat capacity C_V, C_P with pressure P and temperature T, as well as the Grüneisen parameter-pressure-temperature γ (γ-P-T) relationships are obtained systematically in the ranges of 0–70 GPa and 0–1000 K.

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The dynamic strain-induced transformation (DSIT) of austenite to ferrite was investigated under different undercooling conditions using three low carbon Si-Mn steels. The undercooling of austenite (ΔT) was controlled by varying the cooling rate between austenitization and deformation temperatures. Uniform DSIT ferrite grains (∼2.3 μm) were produced at a relatively high deformation temperature above 840°C using a low carbon high Si steel (0.077C-0.97Mn-1.35Si, mass%) in connection with a larger ΔT. The critical conditions for DSIT were determined based on the flow stress-strain curves measured during hot compression tests. Influence of deformation temperature on DSIT of low carbon Si-added steel was also discussed.

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The effects of β and TRIPLEX heat treatment on the microstructure, tensile properties and fracture toughness of in situ synthesized (TiB+La₂O₃)/Ti composite were studied. TRIPLEX heat treatment was beta solution plus alpha–beta annealing plus aging. The microstructure of materials after β and TRIPLEX heat treatment was widmanstätten. Compared with β heat treatment, the length of laminar α after TRIPLEX heat treatment was longer, the α+β colony width was thinner. The width of laminar α after TRIPLEX heat treatment followed by oil quenching was coarser than that after water quenching. Compared with β heat treatment, the ductility of specimens after TRIPLEX heat treatment (oil and water quenching) was improved significantly. The fracture toughness of composite treated by TRIPLEX heat treatment was better than those by β heat treatment. The composites after TRIPLEX heat treatment (oil quenching), had the best tensile properties and fracture toughness.

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Dynamic impact response of Inconel 718 alloy is studied at temperatures ranging from −150 to 550°C and strain rates in the range of 1000 to 5000 s⁻¹ using a compressive split Hopkinson pressure bar. It is found that the flow stress increases with increasing strain rate, but decreases with increasing temperature. The highest work hardening rate is observed in the specimen at the lowest temperature (−150°C) and the highest strain rate (5000 s⁻¹). However, the work hardening rate is weakened by the deformation-induced temperature rise under high strain and strain rate conditions. The strain rate sensitivity increases with increasing strain rate, but decreases with increasing temperature. The activation energy varies as a function of the strain rate and temperature, and has a maximum value of 40 kJ/mol. The greatest thermal softening effect occurs at the highest strain rate of 5000 s⁻¹ and temperatures in the range −150∼25°C. The microstructural observations confirm that the mechanical response of the Inconel 718 specimens is directly related to the effects of the strain rate and temperature on the evolution of the impacted microstructure.

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Hydrogen was introduced in commercial-purity (99%) aluminum by electrochemical charging to study the existing state of hydrogen and its effects on the mechanical properties of aluminum. Electrochemical charging was conducted in an aqueous H₂SO₄ solution with 0.1% NH₄SCN as a hydrogen recombination poison. The potential and pH during the charging were determined from the immune, passive, and corrosive regions in the Pourbaix diagram to determine the optimum conditions for the charging. The maximum amount of hydrogen absorbed was obtained in the immune region. The amount of hydrogen and its existing state were examined using hydrogen desorption curves, which were obtained by thermal desorption spectroscopy. The curves showed distinctive peaks corresponding to trapping sites of hydrogen in the material. One of the peaks was observed at approximately 100°C, and it corresponds to vacancies and dislocations in the material; another peak was observed at approximately 400°C and it corresponds to molecular hydrogen in blisters. It was presumed that charged hydrogen diffuses into the bulk of the material to form hydrogen-vacancy pairs, and then these pairs cluster to form blisters. The fracture strain of charged aluminum in the immune region decreased with decreasing strain rate, showing an inverse dependence on the fracture strain of the uncharged material. This phenomenon was considered to be caused by hydrogen transport by dislocations through the interaction between hydrogen and dislocations. The phenomenon was further confirmed by the observation of hydrogen release during tensile deformation, where the amount of hydrogen was high in the strain rate range where the interaction between dislocations and hydrogen was prominent.

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Onaka has recently (2010) discussed the application of the Hencky equivalent strain to the description of large strains in simple shear in the Journal of the Japan Institute of Metals. We find this analysis in error and introduce below what we consider as the appropriate approach to this problem. We also explain why the Hencky strain is unsuitable for converting the experimental results obtained in large strain shear and torsion to loading along other strain paths.

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The effects of various surface treatments on the friction and wear properties of AZ91D magnesium alloy substrate against the SUJ2 steel ball were evaluated by using a horizontal reciprocating friction and wear test apparatus. The friction and wear properties greatly changed due to the type of surface treatment in spite of being under equal friction and wear testing conditions. Wear loss of AZ91D magnesium alloy anodized from the phosphate solution was greatly reduced in comparison with the other surface treatment such as Dow17, conversion coatings and also no surface treatment. The above results suggest that anodizing from the phosphate solution should improve the friction and wear properties of magnesium alloy used for sliding parts.

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Carbon fiber-reinforced plastic (CFRP) has a great potential application in aircraft fuselage due to its light weight, high specific stiffness and high specific strength. It is crucial to coat the CFRP surface with an electrically conductive material to avoid the damage from lightning strike. Cold spray process has been developed for metallic coating technique. In this study, aluminum coating was fabricated onto the CFRP substrate using interlayer was investigated. It was difficult to fabricate cold-sprayed aluminum coating directly on the CFRP substrate. Though smaller size aluminum particles could be deposited on the CFRP substrate, but the coating was peeled off when the thickness was around 30 μm. On the other hand, it was possible to deposit aluminum coating on the CFRP substrate by plasma spray process. Our proposed structure is using a thin plasma-sprayed aluminum interlayer on the CFRP substrate before doing the cold spray. The interlayer with larger contact area could retain on the substrate and able to facilitate the deformation of the next incoming cold-sprayed particles to build a thick coating. The volume resistivity of cold spray coating is lower than the plasma sprayed aluminum coating because of high process gas temperature in the latter case enhances the oxidation of sprayed particle. Therefore, lower process gas temperature should be used to fabricate lower volume resistivity coating on cold spray.

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Pulsed electron deposition is a very promising means for growing high quality thin films even for complicated oxides. By investigating the influence of deposition parameters like the substrate temperature, the oxygen pressure in the chamber, as well as the pulse frequency and energy of the electrons on the growth of ZnO, the evolution of the [0002] orientation has been revealed and highly [0002] oriented ZnO thin films were obtained on Si (100) substrates at suitable conditions.

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The effect of pre-surface treatment and crystal orientation on microstructural changes in the aluminized 4th generation Ni-based single-crystal superalloy TMS-138 was investigated. The substrate superalloy was cut along the {100} and {110} planes on which three kinds of surface finishing, such as grit blasting, mechanical polishing and electro-polishing were conducted prior to the conventional high-activity aluminizing process. A thermal cycling test at 1373 K revealed that heavy deformation of the substrate surface by grit blasting gave rise to the formation of a secondary reaction zone (SRZ) in the vicinity of the interdiffusion zone/substrate interfaces. When the surfaces were finished by electropolishing, voids were formed in the vicinity of the interdiffusion zone/substrate interfaces. It was also found that accelerated formation of SRZ and voids was observed along the ⟨110⟩ directions rather than the ⟨100⟩ directions during the thermal cycling test. The difference in morphological changes of substrates can be related to the residual stress introduced by the surface finishing.

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The multi-step hydrogenation and dehydrogenation on the pressure-composition-temperature relations for the Mg₁₇Al₁₂-H system was thermodynamically discussed on the based upon the enthalpy for Mg-Al alloy recombination during corresponding reaction with hydrogen. Pressure-composition-temperature diagrams were measured Mg₁₇Al₁₂-H system by means of the volumetric technique in the temperature range of 598–648 K. The isotherms show two step hydrogenation and dehydrogenation indicating a disproportionate formation of MgH₂ via Mg₂Al₃ intermetallic phase. The decomposition of Mg from the intermetallic phase causes thermodynamic destabilisation for the formation of Mg hydrides. The molar enthalpies of hydride formation for the investigated systems are: ΔH_f=−38.5±0.9 kJ (mol_H)⁻¹ for the Mg-H system; ΔH_f=−36±1 kJ (mol_H)⁻¹ for the first-step hydrogenation in Mg₁₇Al₁₂; ΔH_f=−31±1 kJ (mol_H)⁻¹ for the second-step hydrogenation in Mg₁₇Al₁₂.

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Cast Mg-La and Mg-La-Zr alloy ingots were prepared from 99.96% magnesium and 99.9% lanthanum with a zirconium addition made using a Mg-33Zr master alloy. The microstructure was examined and tensile tests performed for the cast alloys. Lanthanum showed a mild grain refinement effect on magnesium, generating coarse equiaxed grains in the casting. The microstructure within the equiaxed grain contained the primary Mg dendrites and degenerated lamellar eutectic in the interdendritic regions. An addition of zirconium to the Mg-La alloys transformed coarse primary α-Mg dendrites into fine globular grains surrounded by eutectic regions. With this change tensile properties improved significantly in comparison with the binary Mg-La alloys of comparative lanthanum content. The hardness value increased linearly with lanthanum content due to an increase in the eutectic Mg₁₂La phase. Fracture occurred owing to the decohesion between the primary Mg grains and eutectic Mg₁₂La phases. An increase in the eutectic regions thus leads to a reduction in ductility by means of crack propagation through the regions.

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In order to replace toxic nickel element from NiTi biomaterials, Ti-Cr and Ti-Cr-X alloys are also new nickel free titanium based alloys for biomedical applications. In this study, comparative study of Ti-xCr-3Sn (x=4, 5, 6, 7, 8 and 9 mol%) alloys was carried out. Ti-4Cr-3Sn and Ti-5Cr-3Sn alloys were composed of α′ martensitic phase (hcp) and other alloys with 6, 7, 8 and 9 mol% Cr were single β phase at room temperature. Among the developed alloys, Ti-6Cr-3Sn alloy showed maximum fracture strain, maximum shape memory effect, maximum pseudoelastic response and minimum hardness and minimum yield stress due to transformation of metastable β phase to stress induced martensite during mechanical loading. Vickers hardness and UTS has increased and fracture strain has decreased with greater than 6 mol% addition of chromium in Ti-xCr-3Sn alloys due to solid solution strengthening, β phase stabilization and slip as dominant deformation mechanism. It is concluded that among the developed Ti-xCr-3Sn alloys, Ti-6Cr-3Sn alloy is hopeful new alloy for biomedical applications.

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Hydrogenation of ethylene (C₂H₄) over intermetallic CeNi₂ and amorphous CeNi₂H_x have been investigated. Amorphous CeNi₂H_x catalyzed hydrogenation of C₂H₄ much more effectively than intermetallic CeNi₂. For amorphous CeNi₂H_x, activity of the hydrogenation of C₂H₄ was drastically enhanced by the presence of H₂ at low temperature (<40°C) in H₂/C₂H₄ whereas no activity was detected in He/C₂H₄ even at 160°C. According to C₂H₄ temperature-programmed desorption measurements, it is concluded that amorphous CeNi₂H_x exhibits high activity due to its disordered structure where absorbed hydrogen plays an important role in the formation of active sites.

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In the present study, REEs were leached from a Vietnamese ore, by using (NH₄)₂SO₄ and REEs were adsorbed from this leachate by blue-green algae (phormidium). In addition, the biosorption characteristics of phormidium for the adsorption of Nd has been studied.
When the concentration of ammonium sulfide was 1%, leaching time was 3 h, and S/L ratio was 0.09, the leaching ratio of Nd was 67.3%. In the adsorption process, when dosage of phormidium was 0.2 kg/L, the contact time was 30 min, and the temperature was 298 K, while pH was kept at the initial value (i.e. pH 5.6), the adsorption density of Nd was 182 mg/kg. These results were similar with the adsorption density of other absorbents, such as: activated carbon, Fe-based absorbent, and calcinated dolomite. Moreover, the equilibrium sorption isotherm of Nd onto phormidium was described by the Langmuir isotherm equation and the pseudo-second-order kinetic model fits the experimental data well.

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Thin films of Pd-Cu-Si metallic glassy alloys for a hydrogen sensor were fabricated by a sputtering method. In order to find out the effect of the composition and the microstructure of them on the hydrogen absorbing property (the H₂ response), the structural parameters based on the short-range order (SRO) were measured. Additionally, the change of the structural parameters with hydrogen absorption was measured, and the correlations of the change with the H₂ response and the hydrogen induced linear expansion coefficient (LEC) were examined. The H₂ response decreased with increases in Si content and the structural parameters. These results can be explained by the positive effects of Si content and the structural parameters on the formation of a trigonal prism which is a structural unit of Pd-based amorphous alloys, and by the negative effect of the trigonal prism on absorbing hydrogen. From the observation of the elongation of the Pd-Pd atomic distance with absorbing hydrogen, H atoms are supposed to occupy the space between Pd atoms. The amount of the change in the Pd-Pd atomic distance showed the positive correlations with the H₂ response and the LEC.

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This study deals with the reduction of tin oxide by hydrogen in the temperature range of 773∼1023 K and the hydrogen partial pressure of 30.4∼101.3 kPa. It aims to investigate the kinetics of the reaction between tin oxide and hydrogen. The hydrogen reduction of tin oxide is to be related with the efforts to extract tin metal with decreasing the emission of carbon dioxide which causes global warming. The experiments were carried out under isothermal condition in hydrogen atmosphere using TGA equipment. The reduction rate of tin oxide to tin metal by hydrogen was found to be relatively fast under the whole conditions until the reduction ratio of SnO₂ approaches to about 0.95. As an example, at 1023 K under a hydrogen partial pressure of 101.3 kPa, almost 100% of tin oxide was reduced to tin metal in 10 min. The nucleation and growth model yielded a satisfactory fit to these experimental data. The reaction was first order with respect to hydrogen partial pressure and had an activation energy of 62.5 kJ/mol (15.0 kcal/mol).

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Low resistivity Cu wires were developed by the combination of lessening impurities through additive-free plating and high heating rate annealing. Resistivities of Cu wires made with the new method were about 30% lower than those made by conventional plating with additives and annealing at the same temperature in H₂. Low resistivity Cu wires were realized even at temperatures 100 K lower than conventional annealing temperatures due to substantial grain growth by the high heating rate annealing in the Cu wires made with the additive-free plating.

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The present study develops two 3-D finite element (FE) thermal models of the temperature field induced within an Alloy 690 butt weld fabricated using the two-pass GTA welding and the laser beam welding (LBW) methods, respectively. The welding thermal cycles of the two welding methods are simulated using ANSYS software based upon a moving heat source model and the high-temperature thermal physical property data are derived in the JMatPro database. The validity of the numerical model is confirmed by comparing the simulation results with the corresponding experimental findings. Agreement is found between the numerical results for the temperature field and the experimental temperature measurements. In addition, the FEM models we use can help us estimate the range and size of the sensitization zone and the time duration of the sensitization temperature. Overall, the results provide useful insight into the sensitization tendencies of Alloy 690 weldments.

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Nano-powders of 1.5TiAl and Al₂O₃ were synthesized from 1.5TiO₂ and 3.5Al powders by high energy ball milling. Nanocrystalline Al₂O₃ reinforced composite was consolidated by high frequency induction heated sintering within 2 min from mechanochemically synthesized powders of Al₂O₃ and 1.5TiAl. The relative density of the composite was 99%. The average hardness and fracture toughness values obtained were 1340 kg/mm² and 9 MPa·m^1⁄2, respectively.

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Magnetic measurements in Ni₅₀Mn_50−xIn_x alloys were performed in order to investigate the effect of the degree of order on the magnetic properties for specimens annealed at different temperatures. It was confirmed that Curie temperature, T_C, and spontaneous magnetization, μ_m, in as-quenched specimens with a low degree of order exhibited composition dependence of indium basically similar to those in as-annealed ones with a high degree of order reported in a previous paper. However, especially in the In-rich region of x>25, both the T_C and the μ_m obtained from the as-quenched specimens were lower than those from the as-annealed specimens.

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In the present work, electronic structures of pure Mg, Mg-Ca and Mg-Al alloys were investigated by first-principle calculations. The charge density between the solute and solvent atoms in the Mg-Ca alloy was lower than that in the Mg-Al alloy. The local charge density of states (LDOS) of Mg atom in the Mg-Ca alloy was almost the same as the LDOS of the Mg atom in the pure Mg, suggesting that the solute Ca atoms had little effect on the Mg-Mg bonding in the Mg-Ca alloy. On the other hand, there is more and deeper valley in the LDOS of the Mg atom in the Mg-Al alloy, compared with that in the Mg-Ca alloy, suggesting that the solute Al atom may increase the covalency of the Mg-Mg bonds. A series of the calculations indicates that Ca atoms enhance the formation of double kinks rather than hinder the movement of dislocations, resulting in solid solution softening of Mg-Ca alloy.

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This paper studied effects of ultrasonic treatment during the solidification process on structure formation of low carbon steel. Results showed that with ultrasonic treatment grains were refined and the steel ingot avoided the cast widmanstatten structure. When ultrasonic treatment was employed, pearlite was broken and the average length of pearlite was decreased from 550 μm to 140 μm. The corresponding aspect ratio was reduced from 12 to 1. At high magnification the treated pearlite was cloud-like, rather than plate-like, as normal. Ultrasonic treatment also can remove the gas from low carbon steel. These phenomena of low carbon steel generated by ultrasonic treatment were explained.

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