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Although Li-BNICs (lithium boron nitride intercalation compounds) have been successfully synthesized by heat treatment, their crystal structures are still not clearly understood and controversial. In this study, several hypothetic phases of Li-BNICs are postulated and their phase stabilities are calculated through applying DFT (density functional theory), a common tool in first principles calculations. According to the experimental results on Li-BNICs, disordered structures have been suggested, which is also analyzed by introducing VCA (virtual crystal approximation) method for a disorder calculation. Lattice parameters, formation energies and electronic band structures for hypothetic Li-BNICs are estimated, where the VCA disorder calculation agrees well with experimental results, exhibiting negative formation energies. Li(BN)9 and Li(BN)3 are suggested as possible phases for Li-BNICs.

Recently, intercalation compounds with various intercalants between hexagonal boron nitride (h-BN) layers have been studied, where lithium BN intercalation compound (Li-BNIC) is one of such compounds successfully synthesized. They are expected to exhibit similar properties to lithium graphite intercalation compounds (Li-GICs) that are known as the anode material for lithium ion batteries. It is difficult, however, to apply Li-BNIC for the batteries due to its returning to an insulator when Li is deintercalated. In this study a Li–BN–graphite ternary system has been focused because it is reported that graphite-like BC2N is a promising material for rechargeable Li batteries. The primary purpose of this study is thus to investigate combined reactivity of BN and graphite with Li through milling and heating processes, and possible intercalation of Li into the matrix: h-BN, graphite or B C N. The pieces of lithium metal, h-BN and graphite powders were ball-milled using a vibratory ball-mill machine and heat-treated at 700 °C for 2 h under argon atmosphere. The samples were then characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, 7Li nuclear magnetic resonance and Differential thermal analysis study. Li-GICs were mainly produced by milling, while post-annealing caused their eliminations and instead produced Li-BNICs with small amount of other lithium compounds. In terms of thermal stability, Li-BNIC is more stable than Li-GICs. In a Li–BN–graphite system, an activation energy of Li-BNIC was estimated to be 119.6 kJ/mol, which is higher than reported activation energies for Li-GICs.

Hexagonal boron nitride (h-BN) exhibits a layered solid structure such as graphite, and the h-BN intercalation compounds (BNICs) have been actively studied as with graphite intercalation compounds (GICs). It is difficult, however, to synthesize BNICs compared with GICs, where the synthesis of BNICs requires high temperature and/or pressure. In this study, the Li-BNIC is synthesized by ball milling and heat treatment, and the samples were characterized by X-ray diffractomety (XRD), differential thermal analysis (DTA) and 7 Li NMR (nuclear magnetic resonance) study. New XRD peaks corresponding to Li-BNICs were observed from the milled sample after heat treating at 700 °C for 2 h. The shifted peaks of h-BN to the lower angles imply an expanded BN lattice through Li insertion. The exothermic DTA peaks observed between 200 and 500 °C might be the synthesis temperatures of Li-BNIC. The NMR spectra of the Li-BNIC are modified according to the ratio of Li to BN, although the corresponding XRD patterns are not changed.

This study investigated zero emissions scenarios with following two originalities compared to various existing studies. One is that we based on A1T society of SRES (Special Report on Emissions Scenario) of IPCC (Intergovernmental Panel on Climate Change) compared to existing studies on those of B1 or B2. The second one is that various innovative technologies were considered and incorporated, such as biomass energy with carbon capture and storage (BECCS), and advanced nuclear technologies including hydrogen or synfuel production. We conducted global modeling over the period 2010–2150 in which energy, materials, and biomass and foods supply costs were minimized by linear programming. We found following features of energy supply structure in A1T scenario. Since the electric demand in A1T scenario in 2100 is two times larger than the others, (1) renewable energy which solely produce electricity, nuclear, and fossil energy with CCS (FECCS) especially coal are main sources of electricity, (2) renewable which can supply heat, namely BECCS and geothermal, satisfies the sector, and (3) hydrogen from coal is introduced in transport sector. It can be concluded that the zero emission energy systems with global economic growth will be possible, by development and deployment of ambitious advanced energy technologies.

In the aftermath of the Paris Agreements, many countries around the globe have pledged to reduce the amount of greenhouse gas emissions being released into the atmosphere. To do so, it is important that the amount of renewable energy in the electricity grid increases. However, there are worries of the capacity of the grid to cope with intermittent energy sources. To assess the feasibility of a 100% renewable energy system in Japan, the authors conducted an hourly simulation of future electricity production based on wind, solar and tidal data. The system was shown to be stable, and the authors calculated the required capacity of electrical batteries that would be necessary to balance such a system.

Mechanochemical (MC) processes are often modified to a large extent with use of process control agents (PCAs). An appropriate PCA is, however, chosen semi-empirically for any MC process such as ball-milling. In this study, milling period and medium, PCA kinds and amount, and powder kinds, are altered as major parameters to systematically and mechanistically investigate the effect of PCAs on powder milling and the related phenomena. The model systems selected are TiO2 and ZnO powders with various PCAs including alkanes, alcohols, water, and a few ionic liquids. According to X-ray line broadening analyses the viscosity and the structure of PCA molecules strongly affect the MC process. In addition, the MC process for harder TiO2 is quite different from ZnO, and oxygen-derived polarity of PCA molecules would cause major difference on the milling behavior. Various parameters controlling the MC process will be discussed.

WC–Co hardmetals are widely used in the cutting industry. Due to several disadvantages of Co binder, many research studies have been carried out to find the suitable binders to replace Co metal. In the present research, AISI304 stainless steel was used as the binder phase to replace Co in WC-based hardmetals. When WC-10AISI304 hardmetals were ball-milled prior to consolidation at 1350 °C for 1 h in a vacuum furnace, brittle η-phase (Fe3W3C) was observed to be formed during sintering. The addition of 1.5–2 wt% graphite to the composition prior to ball milling completely eliminated η-phase formed during sintering of WC-10AISI304 hardmetal. Addition of 2 wt% graphite improves the densification and mechanical properties of the sintered samples by obtaining higher Vickers hardness (HV30) and fracture toughness (KIC) of 1625 kg/mm2 and 10.2 MPa m1/2, respectively. However, the free graphite increases while both hardness and fracture toughness were found reduced beyond this value (2 wt% Cgr).

In the present study, an integrated planning model was developed to find economically/environmentally optimized paths toward future smart electricity systems with high level penetration of intermittent renewable energy and new controllable electric devices at the supply and demand sides respectively for regional scale. The integrated model is used to (i) plan the best power generation and capacity mixes to meet future electricity demand subject to various constraints using an optimization model; (ii) obtain detailed operation patterns of power plants and new controllable electric devices using an hour-by-hour simulation model based on the obtained optimized power generation mix. As a case study, the model was applied to power generation planning in the Tokyo area, Japan, out to 2030 in light of the Fukushima Accident. The paths toward best generation mixes of smart electricity systems in 2030 based on fossil fuel, hydro power, nuclear and renewable energy were obtained and the feasibility of the integrated model was proven.

A simulation model is proposed in the present study to analyze economic and environmental performance of electric vehicles (EVs) operated under different conditions including electricity generation mix, smart charging control strategies and real-time pricing mechanisms. The model is organized into an input-output framework and actualized using an hour-by-hour computer simulation to achieve a real-time electricity supply-demand balance emphasizing the integrations of EVs. The battery cost, real-time solar and wind power generations, and traditional electricity demand are used as preconditions. The model has been developed as a flexible software package and applied to case studies in the Tokyo area, Japan in 2030 with different combinations of three electricity generation mix options, two charging control strategies and two hourly real-time electricity pricing mechanisms. The fuel costs and CO2 emissions of EVs in different operational environments were obtained and compared, and optimized operational conditions for EVs were suggested from the perspective of economic and environmental benefit. The feasibility of the proposed methodology was thereby demonstrated practically through the case studies.

This work investigated the role of NbC on densification, grain growth, and properties of WC-10AISI304 hardmetals sintered by a pseudo hot isostatic pressing process at 1300 °C under vacuum with a pressure of 20 MPa. In this study, in addition to 2 wt.% graphite to reduce the presence of η-phase (Fe3W3C or M6C) during sintering; 1, 1.5, 2 or 5 wt.% NbC was added to a powder mixture of WC-10AISI304. Pseudo hot isostatic pressing enabled densification of the hardmetals, forming more η-phase than with vacuum sintering alone. The addition of NbC leads to a decrease of WC grains and reduces the formation of η-phase during sintering. Elemental analysis showed that a high content (5 wt.%) of NbC encouraged the formation of coarse (Nb, W)C grains, resulting in decreased hardness. Addition of 2 wt.% NbC exhibited the highest Vickers hardness (1820 kg/mm2) with moderate fracture toughness (about 7.7 MPa.m1/2) by encouraging refinement of hardmetal grains and limiting the formation of η-phase during sintering.

The single \(\upbeta\)-MoSi2 phase was prepared by the Na flux method and its stability against thermal, oxidative, and mechanical treatments was investigated. The X-ray diffraction results show that the single \(\upbeta\) phase is formed at 600 °C within 1 h using pre-mixed Mo and Si powders with a Si/Mo molar ratio of 2.00–2.25. By energy-dispersive X-ray spectroscopy, the produced powder is found to be Si-deficient with a Si/Mo molar ratio of 1.87–1.96. The differential thermal analysis shows that the \(\upbeta\) phase transforms into the \(\upalpha\)-MoSi2 phase at 815 °C at 10 K/min with the segregation of a small amount of Mo5Si3. The transformation heat is −5.5 kJ/mol and the activation energy calculated by the Kissinger method is 290 kJ/mol. Thermogravimetry reveals that the \(\upbeta\)-MoSi2−x powder oxidizes significantly at 400–600 °C via the pest oxidation mechanism while it is resistant to oxidation at 700 °C for 5 h similarly to the \(\upalpha\)-MoSi2 phase. At last, mechanical milling on the \(\upbeta\)-MoSi2−x powder with a planetary ball mill up to 216 h demonstrates that this powder is stable under a severe mechanical treatment.

Nuclear power has long been a cornerstone of energy policy in Japan, a country with few natural resources of its own. However, following on from the Fukushima Daiichi accident, the Japanese government is now in the throes of reviewing its nuclear power policy. On the other hand, under continuing policies of greenhouse gas reduction, it is crucial to consider scenarios for the country to realize an economic, safe and low-carbon power generation system in the future. Therefore, in the present study, economic and environmental analysis was conducted on the power generation system in Japan up to 2030 using a multi-objective optimization methodology. Four nuclear power scenarios were proposed in light of the nuclear accident: (1) actively anti-nuclear; (2) passively negative towards nuclear; (3) conservative towards nuclear; and (4) active expansion of nuclear power. The obtained capacity mix, generation mix, generation cost, CO2 emissions and fuel consumption of the scenarios were compared and analysed. The obtained results show that the large scale penetration of PV (photovoltaic), wind and LNG (Liquefied Natural Gas) power can partly replace nuclear power, however, removing nuclear power entirely was not suggested from economic, environmental and energy security perspectives.

Under continuing policies of CO2 emissions reduction, it is crucial to consider scenarios for Japan to realize a safe and clean future electricity system. The development plans for nuclear power and renewable energy - particularly solar and wind power - are being reconsidered in light of the Fukushima nuclear accident. To contribute to this, in the present study, three electricity supply scenarios for 2030 are proposed according to different future nuclear power development policies, and the maximum penetration of renewable energy generation is pursued. On the other side of the equation, three electricity demand scenarios are also proposed considering potential energy saving measures. The purpose of the study is to demonstrate quantitatively the technological, economic and environmental impacts of different supply policy selections and demand assumptions on future electricity systems. The scenario analysis is conducted using an input–output hour-by-hour simulation model subject to constraints from technological, economic and environmental perspectives. The obtained installed capacity mix, power generation mix, CO2 emissions, and generation cost of the scenarios were inter-compared and analyzed. The penetration of renewable energy generation in a future electricity system in Japan, as well as its relationship with nuclear power share was uncovered.

The phase transformation of α-MoSi 2 into β-MoSi 2 induced by mechanical milling (MM) was studied. Planetary ball milling was performed on an α-MoSi 2 powder under six different milling conditions. The X-ray diffraction results show that the dynamic equilibrium between α-MoSi 2 and β-MoSi 2 is reached at low milling intensities, while a single phase of β-MoSi 2 is formed when milled at high milling intensities. The single-phase β-MoSi 2 formation is found to be due to Fe impurity. The mechanism of the phase transformation of MoSi 2 is discussed, and the phase fractions under the dynamic equilibrium are explained by the redistribution of the close-packed layers via synchroshear processes.

The nitrogen absorption and desorption property of LaNi 5 was investigated using NH 3 and N 2 as nitrogen sources. It was found that both as purchased and milling processed LaNi 5 powder can absorb and desorb nitrogen using NH 3 as the nitrogen source, while milled LaNi 5 powder can absorb and desorb more. XRD, cross sectional SEM and EPMA were performed to elucidate the nitrogen stored phases. When N 2 gas was used as the nitrogen source, it was found that the amount of absorbed nitrogen significantly decreased. By using high pressure for the absorption treatment or performing an activation treatment using hydrogen absorption/desorption before the nitrogen absorption treatment, milled LaNi 5 was found to absorb nitrogen of 0.1 mol/mol Finally, the mechanism of the nitrogen absorption was discussed from the EPMA and kinetic data of the nitrogen absorption, and it was suggested that the mechanism of the nitrogen absorption might be explained by a combined model of a diffusion controlled process and an interface controlled process.

Catalytic ability on 12 kinds of carbide powders was investigated at room temperature using NOx gas degradation. They are largely classified into two groups, depending on whether the reaction involves a nitrogen gas in air or not. The carbon dangling bonds largely contribute to the reaction, while the accompanied metal atoms play an important role for adsorbing/dissociating nitrogen gas. Mechanical milling or annealing, as long as without agglomeration, is an effective method for activating powder catalysis, producing new surfaces with plenty catalytic sites. A new concept of catalysis is presented, based on the Schottky barrier-like model, where the charge imbalance is produced at the interface between the non-uniform thin oxide and the carbide.

In this study, the total materials requirement (TMR) to recycle chemical elements from the urban ore by recycling (urban ore TMR, UO-TMR) has been compared with the TMR to extract the element from the natural ore by smelting (natural ore TMR, NO-TMR) in order to evaluate the urban ore grade on an equal footing with the natural ore. A framework of UO-TMR based on the NO-TMR framework is developed. To validate the developed framework, the UO-TMR of a laptop PC is estimated assuming gold, silver, copper, iron, aluminum, tantalum and indium are recycled. It is found that the UO-TMRs for gold, silver, copper, iron, aluminum and tantalum are lower than NO-TMR, but that for indium is higher. The ratio of "urban tailings" is at most 60% of the total, which is smaller than that of NO-TMR "tailings". In contrast to the contributions of energy and material inputs for the recycling process, the contribution of transportation is not very large. For the UO-TMR of indium, the contribution of materials for recycling process is extremely large. The availability and scalability of UO-TMR are also discussed.

—A-0 0.063 0.70 0.013 0.049 A-1 0.086 0.72 0.018 0.069 A-2 0.125 0.75 0.026 0.099 A-3 0.136 0.76 0.029 0.109 A-4 0.150 0.76 0.032 0.119 A-5 0.163 0.77 0.034 0.128 A-6 0.175 0.78 0.037 0.138 A-7 0.188 0.78 0.039 0.148 A-8 0.200 0.80 0.042 0.158

Mixtures of Ti and six kinds of anatase-type TiO2 which differ in adsorbed water content were mechanically alloyed by a planetary ball mill to synthesize TiO. The milled powders were investigated by powder X-ray diffractometry and scanning electron microscopy. The results showed that TiO formation was inhibited by adsorbed water. The effect of adsorbed water on the MA process will be discussed in terms of TiHx formation and local temperature rise. In addition, we also found that polymorphic transformation of TiO2 induced by ball milling was inhibited by adsorbed water.

Mechanical alloying (MA) is one of the most suitable methods to produce alloys with various elements such as refractory, low melting and high vapor pressure materials. The high energy vibrating ball milling was performed under an argon atmosphere both at room temperature and at liquid nitrogen temperature. Small pieces of Li metal and powders of Al, Si and Fe were used as starting materials. In the case of Al–Li, the stable intermetallic compound, β-AlLi, is formed after 10 h of milling. When lithium is milled with silicon at the low temperature, powder is obtained without formation of any compound, while for the milling at room temperature the formation of metastable Li 21 Si 8 is detected by X-ray diffractometry. As for the Fe–Li system, which is immiscible even in a liquid state, evidence of alloying is not observed. The results are explained in terms of the heat of mixing and the mutual diffusivity in these systems. The surface activation of the milled powder will be discussed in terms of the nitrogen reactivity of each milled alloy system.

Mechanical alloying was performed on the Ca–Co system and the nitrogen storage property and magnetization were investigated. The solid solution of Co dissolving Ca is formed during MA process that has limited storage ability, while longer milling produces amorphous/nanocrystalline phase with the ability. The milled Ca–Co powder absorbed and desorbed more nitrogen than pure Ca and Co powder each separately milled and processed. The increase of Ca surface area mainly controls the storage property for short MA, while that for longer MA is ascribed to the non-equilibrium phase. The stored amount for Ca–Co powder increases with milling time, and its magnetization significantly decreased. The large reduction is explained by linear dilution of atomic moment based on the rigid band model, while the deviation from the model for longer MA is explained by formation of the non-equilibrium phase with limited magnetization but with nitrogen storage ability.

It is known that lithium reacts with nitrogen to produce nitride at room temperature. Lithium alloys are one of the candidates for nitrogen absorption materials. On the other hand, it is also known that the mechanical milling is generally used to create various non-equilibrium alloys, which are usually in active powder forms. In this work, in order to activate the nitrogen absorption properties of lithium, the mechanical milling of lithium systems is performed. As the alloying elements, iron and copper are chosen, since both systems of Fe–Li and Cu–Li have no intermediate phase in equilibrium. For mechanically alloyed powders, the atomic structure and the reactivity with nitrogen are investigated using X-ray diffractometry, thermal analysis, etc. In the case of Fe–Li, the mechanically milled sample shows high reactivity with nitrogen for a short milling time, compared with lithium in bulk form. While, Cu–Li forms supersaturated solid solution which hardly reacts with nitrogen at room temperature.

The CO2 decomposition utilizing mechanically milled wustite powders was qualitatively and quantitatively examined and its mechanism was investigated. The wustite phase is stable at least up to 6 h of milling, and the lattice parameter, the crystallite size and the average particle diameter are monotonously decreased with milling time, while the BET specific surface area is correspondingly increased. The mechanically milled FeO powder decomposes CO2 into graphite and amorphous carbon at 773 K, where the decomposition intensity increases with milling time, while unmilled FeO decomposes CO2 into CO with the same annealing condition. It is found that the FeO powder thermally decomposes into Fe and Fe3O4 prior to the reaction with CO2, followed by the precipitated Fe reacting with CO2, and also that the thermal decomposition is promoted by the milling process.

Lithium is one of the active metals and reacts with nitrogen even at room temperature. In this study, in order to grind and activate Li, the mechanical milling of Li with stable metal oxide, namely, Al2O3 and MgO, using a high energy vibrating ball mill was performed. In the case of Li- MgO system, it reacts with N2, but hardly reacts with O2. The reaction with N2 generally produces Li3N, while for some vigorous reactions the Mg3N2 and Li2O are produced as the major phases. In the case of Li-Al2O3 system, however, reactivities with both N2 and O2 are high. The difference will be explained in terms of the reaction mechanism and the Li state.

The potential amounts of dissipated rare metals (Au, Ag, B, Ba, Cr, In, Ni, Pb, Sb, Sn, Sr, Ta, Zn and Zr) in WEEE (Cathode Ray Tube TV, liquid-crystal display TV, plasma display panel TV, refrigerator, air conditioner, washing machine, microwave oven and cleaner) have been estimated. For the estimation, the number of WEEE was also estimated using the population balance model. The composition of the WEEE were examined by interviews and the measurement using energy dispersive X-ray diffractometer. The estimated amounts of the dissipation were evaluated by both the ratio of the dissipation to domestic demand and the weight amount of the dissipation by ‘‘total materials requirement’’ (TMR). [doi:10.2320/matertrans.MAW200781]

Nitrogen absorption and desorption properties as well as possible formation of a non-equilibrium phase were investigated on Ca–Fe powder prepared by ball milling (BM) method. The milled Ca–Fe powder absorbed and desorbed more amount of nitrogen than pure Ca powder and pure Fe powder when each was separately milled and processed. The amount of nitrogen absorbed and desorbed by the Ca–Fe powder is increased with milling time and its magnetization significantly decreased. The large reduction in the magnetization is explained by formation of the non-equilibrium alloy phase in the Ca–Fe powder system, where the new phase is capable of absorbing and desorbing nitrogen and has its magnetization significantly less than pure Fe.

The repeated application of mechanical deformation of metallic materials has been proved to be an effective technique for producing bulk nano-scaled regulated structures. These materials have been shown to have unique properties characteristic for nano-materials. This paper reports the experimental results on the mechanical strength, magneto-resistivity, and thermo-electricity obtained by repeated pressing and rolling of alternately stacked thin metallic foils in the Cu–Fe system. In the samples which have the layer thickness greater than 35 nm, the Hall–Petch relation is primarily obeyed. For the samples with the layer thickness less than 35 nm, the strength and hardness deviate from this relation. Large magneto-resistivity change (GMR) have been confirmed and a noted change in thermo-electricity (EMF) dependent on the layer thickness, as observed for the Ag–Fe system, have also been confirmed.

Multilayers of Fe and Al corresponding to the composition Fe 58 A1 42 (equal layer thickness) have been deposited by sputtering. The as-deposited layers have been characterised by X-ray diffraction (XRD) techniques and transmission electron microscopy (TEM) to determine the initial phases present. The results indicate the presence of both the elements and there is no evidence for any intermetallics to be present in the as-deposited films. The evolution and transformation of these elemental multilayers to intermetallic compound on heating is studied using differential scanning calorimetry (DSC) coupled with XRD and TEM techniques. The results of solid state heat treatment are compared to that of laser mixing carried out on these samples. Attempts are made to understand the sequence of the observed phases from the knowledge of thermodynamics and kinetics.

Multilayers of Ni and Al of 10 nm periodicity have been sequentially deposited by RF sputtering. Only elemental Ni and Al were present in the as-deposited samples. No phase formation was detected until 673 K. For samples heated to 873 K, TEM studies reveal the presence of large grains of $Al_3Ni$ (confirmed with large systematic tilts) and equiaxed nanocrystals of $Al_3Ni$. In addition to the reflections from these two phases, the samples contain additional reflections with streaking from an additional phase. Imaging with these reflections reveals domains with probably strain modulations. Small elongated precipitates of $Al_3Ni$ are also occasionally present in the $Al_3Ni$ matrix. The origin of this complex microstructure is discussed.

Multilayerd Fe-Ag laminates were prepared by the repeated pressing-rolling and hot-sheath-rolling process. As starting materials, Fe sheets (30 or 60μm) and Ag sheets (30μm) were alternatively stacked. In this work, the metallographic structure and the mechanical properties were investigated. The strength of samples was evaluated by extension tests. As the layer thickness reduced, the yield stress became higher due to the grain size reduction and work hardening. The yield stress obeyed the Hall-Petch equation. The maximum yield stress was 850 MPa with 65 nm bilayer thickness, and in the sample of smaller layer thickness than that, strength slightly decreased. Anisotropy of strength was generated by rolling texture and recrystallization texture in the laminates. Strength and ductility varied with Fe and Ag volume ratios following the rule of mixture.

Three polymorphs of titania, rutile, anatase and brookite have been known. In this work, brookite was synthesized from anatase by using a shaker ball-milling (NEV-MA8, Nissin-Giken Co., Ltd). Three experimental conditions, weak, medium and strong ball-millings, varied with changing shaking frequency and TiO2 powder mass, were carried out. It has been concluded that the almost single phase of brookite type titania was obtained after 54ks and 72ks ballmilling under the condition of medium intensity. It has been also found that the brookite obtained in this study shows almost the same photocatalytic activity as anatase.

We have successfully fabricated Fe/Ag multilayers that simultaneously possess the layer thickness of 4 nm and the layer number of above 10 000 by applying the repetition of pressing and rolling directly from a macroscopic stack of metal sheets. The clear correlation between the Ag layer thickness and MR ratio is observed, indicating that the critical layer thickness exhibiting magnetoresistance is 100 nm.

Ti-Al-C composite materials were produced by SHS (Self-propagating High-temperature Synthesis) -Pseudo-HIP (Hot Isostatic Pressing) method. The self-propagating reaction of Ti, Al and C occurred at aluminum melting temperature (933 K). The synthesis conditions to attain high density materials with finely dispersed particles of Ti-Al-C ceramics were confirmed. The composites synthesized at atomic composition of Ti45Al45C10 consisted of TiAl matrix dispersed with the Ti2AlC fine particles of 1-5μm. The micro-hardness and yield stress of this material were, respectively, 4.6 GPa and 1.1 GPa which were much higher than those of Ti-46Al. The wear rate of this composite was approximately 80% of pure tungsten and the constanct to sliding rates.

The purpose of this reseach is to propose a new recycle system of an iron, which is simpler, lower cost and lower energy consumption than the current recycle system. The concept of this system is called "active disassembly" a material includes an actuator which operates under special surroundings. Since large equipment and re-smelting will not be needed, it will be easy to recycle an iron and steel. In this research, Terbium was used as an actuator because rare earth metals have a nature of absorbing hydrogen gas and the volume change during absorbing hydrogen gas. The iron base new material was formed, which includes Th actuator network spread into Fe particle boundary during the sintering process. The Th acutuator was triggered under hydrogen atomosphere and pulverized itself. The material showing the most suitable Tb network was Fe-2at%Tb sintered at 1673K for 600s and became embrittle after heat treatment under hydrogen atomosphere. The recycled materials can be obtain by sintering the pulverized material again at 1673K for 600s. KEY WORDS active disassembly, hydrogen, embrittlement

The synthesis of intermetallic compounds can be carried out through a repeated cold-pressing (RP) technique for binary metallic systems whose large negative heat of formation ensures the solid state reaction. In some cases, those reactions get started on the surface of highly energized regions, called hot spots. In this work, the intermetallic tin-tellurium compound SnTe has been prepared in air and at room temperature by RP of elemental Sn (granular) and Te (shots) precursors. The elemental structure is gradually cold-deformed until the pressing action supplies it with enough mechanical energy (microstrain) as to take the metallic mixture into a violent interaction, via hot spots formation and announced by means of an explosive reaction. Hot spots of 1–2 μm in diameter were visible on the metals surface when the powder particle size was 10–15 nm. That occurred with accumulation of 0.25–0.35% total strain, after 30 times pressing (1.25 g of the elemental mixture at 343 MPa). This indicates a close relationship of the reaction’s ignition point with both the crystallite size and stored strain in the precursor powders. Hot spots trigger the explosive intermetallic synthesis.

In recent years, various studies have been reported on decomposition of carbon dioxide into carbon using iron oxide. This study investigates the ability of mechanically-milled magnetite powder to decompose carbon dioxide as well as the effect of mechanical milling on the crystal structure change. Mechanical milling was performed on magnetite powder using a high-energy vibration ball-milling machine. After 6–12 h of milling, Fe and αFe 2 O 3 phases appear in addition to the magnetite phase, followed by disappearance of the αFe 2 O 3 phase after 24 h of milling, and an FeO phase appears after 72–168 h. The Fe 3 O 4 content phase gradually decreases with milling. The carbon dioxide decomposition with the milled powder was carried out in a quartz tube for 3 h at 773 K. The carbon content of the sample after the CO 2 decomposition increases slightly with the milling time up to 48 h and shows drastic increase when the milling time is longer than 72 h, indicating that the production of FeO phase contributes to the ability of CO 2 decomposition. After the decomposition the sample contains graphite (or other types of carbon), undissolved Fe (both bcc and fcc structure) and Fe 3 O 4 phase.

TiB/Ti composite were produced by SHS (self propagating high temperature synthesis) under conditions of PHIP (pseudo-hot isostatic pressing). The synthesis conditions were optimized to produce highly dense materials conforming a high volume fraction of TiB. Self-propagating reaction of the Ti and B powders occurred above the α- to β-Ti transformation temperature (1155 K). The composites consist of Ti matrices with dispersed TiB reaction products of 2–30 μm size. Near fully dense composites with a TiB/Ti volume ratio of 33–44 vol.% were synthesized for B/Ti atomic ratios of 0.3–0.4 at pseudo isostatic pressures of 100 MPa. The Vickers hardness and fracture stress of the composites are 5.6–7.1 and 2.1–2.3 GPa, respectively, and the wear of the composite is approximately 7–9% of the Ti and Ti–6Al–4V.

The preparation and characterization of metastable phases of the Al–Fe alloy system by mechanical alloying are reported. In Al-rich (up to 10 at.% Fe) alloys, the supersaturated f.c.c. solid solution of Fe in Al (up to 1 at.% Fe) is formed. Almost complete amorphization is confirmed in the composition range 17–33 at.% Fe. The metastable disordered b.c.c. solid solution of about 10 nm in grain size has also been formed by ball-milling for over 180 h in Fe-rich (above 50 at.% Fe) alloys. Examination of lattice parameter and magnetization have shown that the composition range and degree of disorder are comparable to those formed by crushing and sputter deposition.

Multilayer structured alloys which have a layer thickness less than 10 nm have been produced by the application of repeated pressing and rolling to the initially macroscopically thick layered sample. The TEM observation of a Ag/Fe sample revealed a regular alternate lamination of Ag and Fe with the layer thickness in the range of 10 nm. The measured electrical resistivity showed a large dependence on the applied magnetic field which is characteristic to the composite structure of magnetic and non-magnetic metals in the thickness range of nanometers.

Ball-milling of graphite powder was performed by the use of a stainless steel ball-mill and an agate ball-mill. The crystal structure of the ground graphite was studied by transmission electron microscopy and X-ray diffractometry. A spectrometric approach to the change of structure during the milling process was also carried out by the carbon Kα X-ray-emission band spectroscopy (XES). The carbon Kα XES spectra were compared with those of carbon materials such as ball-milled diamond powder, i-diamond film and amorphous carbon powder. In the case of the stainless steel ball-milling, microcrystalline and/or onion-like structure were formed. The XES spectrum suggested that sp3 hybrid orbital was formed after 2000 h of milling. While, in the case of an agate ball-milling, it was suggested that the 2p orbital became narrow as a result of further finely-ground pulverization of graphite crystallite after 1750 h of milling.