The martensitic phase transformation (MT) start-strain of NiTi shape memory alloy under uniaxial tension is predicted theoretically on the basis of micromechanics. Results directly show that the martensitic transformation start-strain depends on three kinds of parameters: lattice correspondence strain (Bain strain), mechanical constants of Nitinol (Young’s module, Poisson ratio) and chemical energy difference between austenite and martensite phase (temperature dependence parameters). Comparison of this new prediction with other methods and experimental data is also given.

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The effect of training strain, deformation temperature and number of training cycles on the two-way shape memory effect (TWSME) and its stability have been investigated systematically in a Ti_46.3Ni_44.7Nb₉ (at%) wide hysteresis shape memory alloy (SMA). The experimental results indicate that two-way shape memory strain increases with increasing the training strain up to 14.5% and then decreases with further increasing the training strain. When the training strain is less than 12%, the two-way shape memory strain increases with the increase of number of training cycles in the Ti_46.3Ni_44.7Nb₉ alloy deformed at the room temperature. Compared with TiNi binary alloy, the TWSME is smaller and the training strain to get the maximum TWSME is larger in the Ti–Ni–Nb alloy due to the deformation of β-Nb soft particles during training. However, the Ti–Ni–Nb alloy exhibits excellent stability of TWSME during the thermal cycling.

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In many cases that shape memory alloys are applied to engineering and medical fields, it is necessary to deform them in martensitic phase and after that, to recover them by heating. However, if a slip-deformation occurs, a shape recovery does not occur completely even if heated up above a reverse transformation finish temperature A_f. It is reported that transformation temperatures are changed by pre-deformation and in constrained strain condition. Therefore, it is important to investigate the relationship between the pre-deformation and the deformation and transformation characteristics such as the recovery stress, the transformation temperatures and so on. The purpose of this paper is to clarify the influence of the pre-deformation on the recovery strain, the recovery stress and the transformation temperatures in a Ti–Ni shape memory alloy. The material used in this study is Ti–50 at%Ni alloy annealed at 1103 K for 60 s. The variation of the recovery strain, the recovery stress and the transformation temperatures by the pre-straining are investigated experimentally, and also the variation of the transformation and deformation characteristics by the pre-straining is discussed in relation to the volume fraction of slip-deformed martensite.

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A series of uni-axial tensile cycling tests were conducted at room temperature in superelastic NiTi strip specimens with nano-grain size. The NiTi superelastic strip specimen’s Apparent Young’s Modulus (AYM) and the critical stress decrease when the specimen is subjected to an external uni-axial stress and the strain being higher than 1.5%. Both of the AYM and the critical stress become steady after 10-time cycling. The number of the (111)[1\\bar43] oriented grains increases with extending the strain value. The sub-grain size grows with increasing mechanical cycling number due to the annihilation of the small angle boundaries. The AYM-softening is related to the grain re-orientation (texture evolution) and the formation of irreversible-stabilized B19′ martensitic variants. The softness of the critical stress is principally attributed to the aspect that the grains re-orient to align along the two textural components (111)[1\\bar10] and (111)[1\\bar43] when the external stress being applied. The rotation of grains towards the observed orientation gives higher Schmid factor for the transformation and is one of the reasons for the decrease in AYM and critical stress. The orientation relationships between B2 parent phase and the strain-induced B19′ martensite are observed to be: [111]_B2||[10\\bar1]_M, (1\\bar10)_B2||(010)_M and [111]_B2||[\\bar110]_M and (1\\bar10)_B2||(001)_M.

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Microscopic mechanism of martensitic transformation in nickel (Ni)–titanium (Ti) alloy is investigated by molecular dynamics (MD) simulation using embedded atom method (EAM) potentials. The computational parallelepiped specimen with nano-size dimension is surrounded by Ti-terminated free surfaces and constrained regions for loading. The detection method of martensite phase is newly exploited. The crystalographic B19′ monoclinic crystal form can be identified as martensite phase by checking up atomic lengths and angles of neighborhood and by comparing them with possible values of lattice parameters already proposed. In tensile loading, the specimen shows a kind of stress-induced transformation from parent phase (B2 structure) to martensite phase (B19′ structure). Outbreak of martensitic transformation occurs immediately after stress reaches maximum value. In outbreak of martensite, distortion of unit structure is observed as an actual change in atomic coordinates. It is found that there are two major transformation paths both resulting in martensite structure, each of which has contrary sequence of changes in atomic length or angle. There is also the other route of atomic movement for completing martensitic transformation with relatively long-range atomic migration. The EAM potential used in the present study is discussed as to crystalline energies of periodic B2 or B19′ unit structures. Dynamic energies in transformation are also obtained from MD results and they show that there are energy barriers in martensitic transforming. Static evaluation of energy, on the assumption of uniform transformation, is carried out and is compared with energy change obtained by MD method.

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A new method of pipe joining using shape memory alloys (SMAs) is proposed in this study to obtain the maximum and uniform joining stress. Fe-based SMAs, regarded as potential alloys for pipe couplings, is not so widely industrialized as anticipated. The major obstacle is error of pipe size, which causes a gap between deformed SMA joint and pipes to be joined prior to heating. Since the recoverable strain of Fe SMAs is comparable to the gap, most of the strain is wasted as free recovery. In this study, the problem is settled by deforming simultaneously SMA coupling and pipes to be joined with the coupling inserted in the pipes. By doing so, there is always no gap between coupling and pipes prior to heating. The new method makes it possible to apply alloys with a poor shape memory effect (SME) to pipe couplings. Some other expected advantages and disadvantages will be discussed.

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A promising field for applications of shape memory alloys (SMAs) in the near future is the micro-actuator technology. Especially, two-way shape memory effect (TWSME) is the most suitable to apply in actuators, because a pre-determined response can be obtained very easily by thermal changes against shape memory elements.
In this paper, the TWSME in Ti–Ni–Nb alloy was investigated quantitatively by applying various levels of pre-deformation. The deformation in a complete martensite phase was applied by a thermo-mechanical treatment in order to obtain the two-way memory strain. The experimental results indicated that the deformation mechanism in a martensite phase was just the martensite reorientation accompanied by the dislocation slip. The dislocation due to the slip deformation is the origin of the internal stress field that is necessary to generate the two-way memory strain. However, excessive introduction of the dislocation decreases the two-way memory strain. The maximum two-way memory strain observed in this experiment was 2.1% at an applied strain of 18%. In addition, pre-deformation increases the temperature of reverse transformation, but decreases the temperature of martensitic transformation. These experimental results can be explained by using the series-parallel combined model that has been suggested in our previous work.

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The influence of strain ratio on bending fatigue properties of TiNi shape-memory alloy thin wires and the process of fatigue crack propagation were investigated. The results obtained are summarized as follows. (1) The martensitic transformation stress of a superelastic thin wire is higher than that of a shape memory wire, resulting in shorter fatigue life of the superelastic wire. The maximum bending strain of fatigue limit is the martensitic-transformation starting strain. (2) The plane-bending fatigue life curve is expressed by a power function of maximum strain ε_max and the number of cycles to failure. The smaller the strain ratio, the shorter the fatigue life. (3) In both rotating bending and plane bending, fatigue cracks nucleate on the surface of the wire. One fatigue crack grows preferentially and the fatigue-crack propagated region of fracture surface is fan-shaped. (4) If ε_max is larger than 1%, ε_max during the rotating-bending fatigue test becomes a little smaller than that of the initial value. (5) The fatigue crack length can be estimated by measuring increase in electric resistance based on decrease in cross-sectional area due to fatigue crack propagation. (6) The fatigue crack length of the notched wire is expressed by a power function of the number of cycles.

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The main purpose of the present research is the measurement of local strain distributions generated in a shape memory alloy composite (SMAC) under thermal loading. In the present study, firstly, the test system is constructed on the basis of Digital Image Correlation (D.I.C.) in order to measure local strains all over the surface of object. Then, local strain distributions generated in SMAC are measured under heating. Results in present study are as follows: (1) Longitudinal local strain reveals inhomogeneous deformation behavior during austenite transformation of SMA fiber, and shows distribution along to x and y direction after austenite transformation. Also, we can see that the state of distribution is different between x and y directions after austenite transformation. (2) Lateral local strain begins to generate around fiber during austenite transformation of SMA, and shows distribution along to only y direction after austenite transformation. This distribution is caused by thermal expansion of matrix. (3) Shearing local strain begins to generate at fiber edge during austenite transformation of SMA fiber, and shows distribution along to x and y direction after austenite transformation.

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Attempts have been made to develop new types of seismic devices using shape memory alloys. They are a single-stage bellows which are processed from thin-walled tubes by employing the rubber bulge method and then are annealed at 400°C for the shape-memory treatment. As strain distribution is induced on the bulged part due to the process, it is significant to know the effects of pre-strain and the subsequent heat-treatment on the mechanical properties of the material for tube when designing the bellows shapes for the seismic structures. Thus, tensile tests and thermal analysis were conducted before and after the heat treatment on rectangular specimens cut from the tubes.
In this paper, the oxidization method was first attempted to observe distinctively both regions of the stress induced martensite (SIM) transformation and twin deformation generated while applying strain to the specimens. It became clear that the micro-structure in the SIM area had a changed R phase from the austenite phase at room temperature after being annealed at 400°C. From the experimental and analytical results for the specimens, the mechanical behavior was classified broadly into two conditions as follows: (1) the mechanical behavior can be formulated on the basis of a series-model consisting of areas of both R phase and austenite considering the area-ratio of these phases until the SIM transformation has expanded over the whole specimen, and (2) after that, the mechanical behavior can be formulated using the exponential function for the applied strain as a parameter.

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The aim of present paper is the investigation of relationship between inhomogeneous deformation behavior and macroscopic deformation behavior arising in SMA during cyclic loadings. Firstly, a test system was constructed on the basis of Digital Image Correlation in order to measure inhomogeneous deformation behavior. Secondary, measurements of the inhomogeneous deformation behavior (local strain distribution) arising in 50.5Ni49.5Ti plate were tried during cyclic tensile loading–unloading in the region of pseudoelastic temperature. From some results, it is seen that the inhomogeneous deformation behavior sensitively changes according to the state of loadings (i.e., number of cycle, history of loading and so on). Also, the macroscopic deformation behavior for SMAs is strongly affected by the inhomogeneous deformation behavior. It is very important for application of SMA to investigate the relationship between macroscopic deformation behavior and inhomogeneous deformation behavior.

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It is reported that the transformation characteristics of Ti–Ni shape memory alloys (SMAs) are influenced by manufacturing conditions, such as composition, heat-treatment temperature, cold working, and so on. To understand correctly the effects of these manufacturing conditions on transformation characteristics of Ti–Ni SMAs make it possible to control the transformation temperature and recovery stress. The purpose of this work is to clarify the effect of cold working ratio on transformation and deformation behavior after pre-deforming SMA. The specimens were Ti–50 at%Ni annealed at 673 K for 3.6 ks. The variation of the recoverable strain, recovery stress and transformation temperature with cold working ratio was investigated experimentally. The solution treated material was also used as a reference material. The effect of cold working ratio on the transformation and deformation behavior is discussed in relation to the volume fraction of the residual martensite subjected to slip deformation.

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The dynamic impact behavior of bare and carburized NiTiCu shape memory alloy was studied using a home-built impact testing system in this paper. The contact force and contact time between impactor and specimen at different impact energy were measured in real time by force sensor, and predicted formulae about parameters during impact process were presented. The results showed that the contact force and contact time of carburized specimens were less than these of bare specimens, and the absorbed energy of carburized specimens due to stress-induced martensitic transformation was higher than that of bare specimens. These results indicated that the carburization process could reduce contact force and material damage of NiTiCu alloy during impact process.

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The thermomechanical processing consisting in cold work (true strain e=0.3–1.9) followed by a post-deformation annealing (200–700°C temperature range) is applied to the equiatomic Ti–Ni alloy. The evolution of the structure, substructure and functional properties of the material is studied. For all levels of cold work, the maxima of the free recovery strain and constraint recovery stress are obtained after annealing in the 350–400°C temperature range. For a moderately cold-worked material (true strain e=0.3), this temperature range corresponds to polygonization; for a severely cold-worked material (e=1.9), it corresponds to the material nanocrystallization, while for a highly cold-worked material (e=0.88), the structure is mixed. An increase in the cold-work strain leads to an increase in the completely recoverable strain above 8% and in the maximum recovery stress up to 1450 MPa, as well as to the widening of the superelastic temperature range.

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The crystal structure of a new phase with an approximate composition of Mg₉₁Ce₇Zn₂, which is formed as a main phase in an Mg₉₁Ce₆Zn₃ alloy, has been determined by atomic-scale observations of high-resolution transmission electron microscopy (HRTEM) and high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). The structure of this phase can be described as a one-dimensional incommensurate structure with an orthorhombic unit cell of a=1.03 nm, b=1.03 nm and c\\fallingdotseq3.7 nm, formed by insertion of anti-phase boundaries in the fundamental Mg₁₂Ce (Mn₁₂Th-type) structure with a tetragonal unit cell of a₀=1.03 nm and c₀=0.60 nm. The anti-phase boundaries are parallel to the (001) plane of the fundamental tetragonal structure, and an average interval of the boundaries along the [001] direction is about 3.1c₀. Also, a commensurate structure with an interval of 5.5c₀ is observed as a coexisting phase with the incommensurate structure.

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We have investigated the magnetic properties of Cd atoms decayed from ¹¹¹In at the interfaces of Fe/Ag evaporated films. In order to determine the magnetic properties of the films, we have measured ¹¹¹Cd(←¹¹¹In) time differential perturbed angular correlation (TDPAC) spectra at room temperature as a function of distance from the interface. Fe and Ag were evaporated using electron beam evaporation, and small amounts of radioactive ¹¹¹In were evaporated by resistance-heating. The evaporated films had the following stacking orders on kapton polyimide film substrate: (1) polyimide/Fe 50 nm/¹¹¹In/Fe x nm/Ag 20 nm (x=0.2,0.3,1,3,5,10), (2) polyimide/Fe 50 nm/Ag x nm/¹¹¹In/Ag 20 nm (x=0,0.2,1). We used an Ag layer as a cap layer in order to prevent oxidation in air. TDPAC spectra were measured using a four-detector arrangement. The hyperfine magnetic field tends to be slightly larger when ¹¹¹In is close to the interface of the Fe/Ag layer. The intensity of perturbation damps rapidly as ¹¹¹In is close to the interface of Fe and Ag. These behaviors are thought to depend on electric field gradients and the influence of the surface roughness.

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The deformation of monolithic bulk-metallic glasses (BMGs), nanocrystal-containing, and micrometer-sized, ductile-particle-reinforced bulk metallic glass composites (BMGCs) has been investigated. The number density of shear bands, the interaction of shear bands with the particles, as well as the apparent plasticity was found to be significantly different in three types of samples before failure occurred. The interaction of shear bands with the micrometer-sized particles implied that shear bands can be initiated by stress concentration at the particle boundaries and, at the same time, absorbed by the deformation of particles. It is hypothesized that the observed number density and motion of shear bands could arise from the interaction of rotational sliding of medium range order (MRO) or dense-packed clusters, fine crystals, and the free volume in the material. An estimate of the shear band thickness, based on the size of particles or grains near and in the shear bands of the BMGs, BMGCs, and ultra-fine structured materials is consistent with this conjecture.

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At interconnection between a Ag-base conductor alloy and a Sn-base solder alloy, fast penetration of Sn into the conductor alloy occurs due to diffusion induced recrystallization (DIR) during solid-state heating under usual energization conditions. Like formation of binary Ag–Sn compounds, the penetration of Sn deteriorates the electrical conductivity at the interconnection. In order to examine the penetration rate of Sn into the conductor alloy, the kinetics of DIR in the Ag(Sn) system was experimentally observed in the present study. The experiment was carried out using Sn/Ag/Sn diffusion couples prepared by a diffusion bonding technique. The diffusion couples were isothermally annealed at temperatures of T=433–473 K for various times up to t=1100 h in an oil bath with silicone oil. Due to annealing, a region alloyed with Sn is formed in Ag due to DIR at T=453 and 473 K. At T=433 K, however, the DIR region could not be recognized clearly. The concentration of Sn in the DIR region is about half of the solubility of Sn in Ag. The mean thickness l of the DIR region reaches to 4 μm for t=1100 h at T=453 K and 5 μm for t=890 h at T=473 K. The experimental results were theoretically analyzed using mathematical models. The analysis indicates that the growth of the DIR region is controlled by the interface reaction at the moving boundary of the DIR region within the experimental annealing times. At longer annealing times, however, the interface reaction is no longer the bottleneck for migration of the moving boundary and the grain boundary diffusion across the DIR region governs the growth of the DIR region.

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In a bronze method, uphill diffusion of Sn takes place from a binary Cu–Sn alloy to Nb₃Sn during reactive diffusion between the Cu–Sn alloy and Nb at temperatures around 1000 K. In order to account for the occurrence of the uphill diffusion quantitatively, the phase equilibria in the ternary Cu–Nb–Sn system were theoretically analyzed using a thermodynamic model for phases with different sublattices. In this ternary system, there is no ternary compound and the solubility of the third component is very small for all the phases. Consequently, the ternary interaction was assumed negligible, and thus the Gibbs energy of each phase was expressed with the thermodynamic parameters of the relevant binary systems. In an isothermal section calculated at 1053 K, the three-phase equilibrium of Cu + Nb + Nb₃Sn appears at an activity of Sn with 0.0047. If the activity a_Sn^b of Sn for the binary Cu–Sn alloy is greater than the activity a_Sn^c of Sn for the three-phase equilibrium of Cu + Nb + Nb₃Sn, Nb₃Sn is spontaneously produced owing to the reactive diffusion. As a result, the uphill diffusion of Sn occurs from the Cu–Sn alloy to Nb₃Sn. The chemical driving force ΔG_Sn for the uphill diffusion is evaluated by the equation ΔG_Sn=RTln(a_Sn^b⁄a_Sn^c). This equation semi-quantitatively explains the growth behavior of Nb₃Sn.

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Two types of aluminum bicrystals (Bicrystal 1 and 2) having an asymmetric tilt grain boundary were grown. In Bicrystal 1, the orientations of component grains were related to each other by 45° rotation about the normal of the wide surface of the tensile specimen. In Bicrystal 2, although the primary slip planes were symmetric about the grain boundary plane, the component grains were related to each other by 180° rotation about the tensile axis of the specimen. The specimens were deformed to a tensile strain of 0.3 and subsequently annealed. In both bicrystals, deformation bands were not formed symmetrically about the grain boundary. After annealing, no strain induced boundary migration was found. Recrystallization occurred through ⟨111⟩ rotation mechanism. These results were compared with the deformation and recrystallization in aluminum bicrystals having a symmetric tilt grain boundary.

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Dense TiSi₂–SiC and TiSi₂–SiC–Ti₃SiC₂ composites in which SiC particles in 200–300 nm disperse, were reactively synthesized through spark plasma sintering (SPS) technique using TiC, Si, and C powders in micrometer as starting reactants. The phase constituents and microstructures of the samples were analyzed by X-ray diffraction, field emission scanning electron microscopy and transmission emission microscopy. The hardness, fracture toughness and bending strength of TiSi₂–SiC and TiSi₂–SiC–Ti₃SiC₂ composites were tested at room temperature. The fracture toughness and bending strength of TiSi₂–SiC–Ti₃SiC₂ composites reach 5.4±0.3 MPa·m^1⁄2 and 700±50 MPa, respectively. The factors leading to the improvement of the mechanical properties were discussed.

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Titanium dioxide (TiO₂) coatings were prepared by chemical conversion treatment of aluminum in (NH₄)₂TiF₆ with H₂O₂, and the sintering of the coating was prepared to immobilize the photocatalyst on aluminum. Coatings were also formed in this solution at room temperature. To identify the coating structure, coating analysis was carried out using an infrared absorption spectrum analyzer. Based on the infrared absorption results, a component of the coating was found in the hydrolysis product of peroxo titanium fluoride. Furthermore, the coating analysis was carried out using X-ray diffractometry (XRD), and non-sintered coating was amorphous; however, the coating sintered by 673 K was anatase-type titanium dioxide.
In the forming process of the conversion treatment in (NH₃)₂TiF₆ and H₂O₂, first, the generated F⁻ in the bath reacted with the aluminum. At the same time, hydrogen ions on the aluminum surface were consumed because hydrogen gas was generated. Thus, the pH of the interface became alkali. The hydrolysis of the titanium peroxo fluoride was deposited on the aluminum because pH increased on the surface.
The coating sintered at 473 K had the highest activity. The photocatalytic activity of the coating sintered at 623 K was lower than the coating heated at 473 K, which is attributed to TiO₂ aggregation This forming process of the coating is low cost because of the useless electrolytic decomposition process. Furthermore, practical industry is expected because immobilized substances on aluminum can easily be decomposed at low temperatures.

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By employing an electrochemical technique incorporating magnesia-stabilized zirconia electrolyte, the activities of iron oxide, Fe_xO, were measured in magnesiowüstite, Fe_xO–MgO solid solution, in equilibrium with solid metallic iron at temperatures between 1373 and 1573 K. The sub-regular solution model was applied to the Fe_xO activities, and the calculated Fe_xO activities were in good agreement with the experimental values in this study and the literatures at temperatures between 1073 and 1573 K with an accuracy of ±0.02.

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Low-energy characteristic X-ray emission is detected during bombardment of positive low energy ions onto insulator materials. The phenomenon is considered to be related to surface charge-up. To study further the mechanism, the characteristic X-rays was studied during 30 keV Ga⁺ ions bombardment onto Al₂O₃ monocrystalline specimens applied with a direct current (DC) bias in the present work. The applied DC voltage builds an electric field parallel to the surface of the specimen. The results show that the characteristic X-rays of O-Kα and Al-Kα increased with the increasing of the applied DC voltages.

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Scrap metal often includes a large amount of copper and tin. It is important to recover copper and tin from this scrap metal for recycling. Separation into two liquid phases, namely Fe and Sn(–Cu) phases, has been investigated at 1523 K in Fe–Sn–B and Fe–Sn–Cu–B systems. In the Fe–Sn–B system, the tin content of the Fe-rich phase and the iron content of the Sn-rich phase are 13.7 and 11.7 mass%, respectively, when [mass%B]_{(in Fe)}=3.62. Boron widens the miscibility gap of the Fe–Sn binary system. The isothermal section diagram of the Fe–Sn–Cu–2.66 mass%B quaternary system at 1523 K is described. In the Fe–Sn–Cu–B system, separation into two liquid phases, Fe-rich and [Sn–Cu]-rich, is found over all ratios of [mass%Sn]/[mass%Cu]. The separation region is enlarged as the [mass%Sn]/[mass%Cu] ratio is decreased. By using the separation into two liquid phases, iron can be enriched in the Fe-rich phase and copper and tin can be enriched in the [Sn–Cu]-rich phase. It is possible to recover copper and tin effectively from Fe–Sn–Cu alloy.

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Aluminum was anodized in a Na₃PO₄ solution, and then platinum and tin were electrodeposited into nano pores of anodic oxidation film in H₂PtCl₆ and SnSO₄ solutions. Titanium (IV) oxide (TiO₂) thin film was immobilized on electrolytically colored anodic oxide coating of aluminum. The photocatalytic activity of prepared films was analyzed for photolysis of the malachite green. In the results, the photocatalytic activity of Pt loaded TiO₂ (TiO₂/Pt/Al₂O₃) film was highest in all films, and the relation between the amount of metallic colloid and photocatalytic activity was confirmed. Photocatalytic activity improved with increase of the electrodeposition amount, and activity was highest when the amount of platinum was about 4.2×10⁻⁵ kg·m⁻². But photocatalytic activity began to decline when the amount of platinum exceeded 4.2×10⁻⁵ kg·m⁻² because the platinum had a recombination center and decreasing surface area by electrodeposition. The photocatalytic activity of Sn loaded TiO₂ (TiO₂/Sn/Al₂O₃) film didn’t reach that of the TiO₂/Pt/Al₂O₃ film. However, that indicated photocatalytic activity of about 1.6 times compared with TiO₂/Al₂O₃ film. SnO₂ manifested photocatalysis as well as TiO₂ because it was confirmed that sintered tin was SnO₂ in the results of XPS.
Therefore, anodic oxidation film and electrolytically colored anodic oxide coating were effective substrates of photocatalytic films.

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5052 aluminum alloy plate used for substrate and 2017 aluminum alloy bar used for coating rod, both monolayer and multilayer friction surfacing were done using a numerical controlled full automatic friction welding machine. Effects of the surfacing conditions on structure and mechanical properties of both monolayer and multilayer deposits were investigated. It was clearly observed that the circular pattern appeared on the surface of both monolayer and multilayer deposits by the rotation of coating rod, and the interval of circularly pattern become narrower with increasing of the rotation of coating rod. The monolayer deposit has a tendency to incline toward right side (Retreating side) further than center of deposit for the feed direction of coating rod. And, the 2nd surfacing of multilayer deposit recognized to incline toward the 1st deposit side. A little of incomplete welds was observed at both sides of monolayer deposit. The incomplete parts of welds 1st deposit in multilayer deposit were disappeared by 2nd surfacing. Microstructures of both monolayer and multilayer deposits were finer than those of the substrate and coating rod. The deposition efficiency of 2nd surfacing in multilayer deposit showed higher value than that of the monolayer deposit. Hardness of both deposits showed higher value than that of the substrate and same value of coating rod. The softened area was recognized at 2.5 mm distance from the weld interface of substrate and coating rod. The tensile strength of multilayer deposit showed higher value than that of the monolayer deposit, and both deposits showed higher value than that of the substrate.

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Magnesium alloy offers an outstanding combination of light weight, ease of manufacturing, and good engineering properties. The most common method to manufacture magnesium alloy products is die-casting; however defect rate for magnesium alloy die-casting is still relatively high. Especially in case of thin-sectioned die-casting, mold filling may not be accomplished occasionally due to its fast solidification rate. As a result, fluidity (i.e. the ability of filling a cavity) becomes very essential.
In this study, a unique “melt droplet experiment” is proposed and conducted to examine the fluidity performance of magnesium alloys on various mold surfaces treatment, including plain SKD61 molds, vacuum nitration treated SKD61 molds and 4 other types of ceramic coating on SKD61 molds, TiAlN, CrN, AlCrN and CrC. In the beginning a variety of magnesium alloys with known fluidity are examined to validate this method’s legitimacy. The effect of mold surfaces coating treatment on fluidity of magnesium alloy AZ91D was studied.
Different types of surface coatings are applied on mold to distinguish the influence on fluidity performance. It is realized that surface coatings have certain enhancement towards fluidity length. For example, fluidity on the TiAlN coated molds was about 40 mm, while non treated plain molds exhibited 29 mm of fluidity, although their microscopic structure and surface roughness are similar. The difference of fluidity performance between them is about 35%. From the experimental results and heat transfer point of view, thermal properties of mold surface coating may be related to the fluidity difference.

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The layer thicknesses of rapid prototyping 3D parts must be minimized to reduce the dimensional tolerance and improve the surface roughness. This paper studies the thinnest layer feasible by Ceramic Laser Sintering (CLS) and analyzes the reasons why ultra-thin layers could be built with CLS.
Manufacturing a work piece with a proper scanning parameter (3200 mm/s scanning speed, 33 W laser power) verified a 20-layer square work piece could be made successfully with 0.015 mm layer thickness, which is the thinnest layer made by a powder-based process.
Regarding the feasible layer thickness, effects of the following four significant influential parameters were discussed: (1) powder particle size, (2) paving force carrying capacity of paved layer, (3) upward deformation of the property transformation zone, and (4) anti-fracture strength of the property transformation zone.
The reasons why CLS could build ultra-thin layers were: (1) layers were built with slurry; (2) the inherent solid green support could withstand the paving force and prevent excessive upward deformation; (3) the lowest working temperature was decreased from 1800°C of Ceramic Laser Fusion to 1200°C.

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Microwave (MW) heating behavior of various metal particles was investigated using a single-mode applicator. Considering the distributions of the electromagnetic fields in the wave guide, specimens were placed at four specific positions with respect to the electric and the magnetic fields of MW. They were heated at conditions of constant power input.
It was demonstrated that iron particles were heated well in the magnetic field, and that ferro-magnetic metal particles having the higher Curie point was heated the better. It was possible to heat iron bulk particles (∼3 mm) in a magnetic field without occurrence of electric discharge. In the range of nickel particle size between 45 and 150 μm, the particles with the smaller size were heated the better.
Nickel oxide (NiO) was heated well only in the position of large electric field, which indicates that the heating was caused by the different (dielectric heating) mechanism from the metal particles.
From these results, contribution of magnetic field to heating metal particles was discussed, considering the heating mechanisms of the magnetic loss and the eddy current loss. The dependence of the heating rate of metal particles on their size was discussed in terms of the heat transfer rate.

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(1−x)La_2⁄3TiO₃–xLa(Mg_1⁄2Ti_1⁄2)O₃ ceramics with x ranging from 0.1 to 0.9 were prepared by conventional solid-state reaction. La_2⁄3TiO₃ and La(Mg_1⁄2Ti_1⁄2)O₃ were found to form a solid solution over the whole compositional range. However, the second phase La₂Ti₂O₇ existed for x=0.1 and 0.3. As the x value increased from 0.1 to 0.9, the dielectric constant ε_r decreased from 65.1 to 28.4. The oxygen vacancies were the main factor affecting the Q×f values of the (1−x)La_2⁄3TiO₃–xLa(Mg_1⁄2Ti_1⁄2)O₃ ceramics. A τ_f value of −5 ppm/°C can be obtained at x=0.3.

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The magnetic microstructure of Alnico 5 and Alnico 8 and their magnetization process were investigated systematically at a nanometer scale by means of electron holography and Lorentz microscopy. In particular, the magnetization process in Alnico alloys was visualized for the first time by utilizing a sharp magnetic needle made of sintered Nd₂Fe₁₄B in a transmission electron microscope. It was found that the direction of lines of magnetic flux changed at the boundaries between the α₁ and α₂ phases which were aligned in the direction of the magnetic field applied in the thermomagnetic treatment. In the Lorentz microscope image, these boundaries were observed as white lines and black bands, whose shapes reflected the difference in the shape anisotropy between Alnico 5 and Alnico 8. With an increase in the magnetic field induced by the magnetic needle, the magnetization direction of the domains magnetized in the direction opposite to that of the approaching needle was reversed, and finally a large reversed domain was formed. In both Alnico 5 and Alnico 8, it was shown that the magnetization process was accomplished through an entire magnetization reversal in each grain of the α₁ phase.

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Many institutes and companies are currently researching into eco-efficiency and Factor X as evaluation methods for environmentally conscious design. However, no standard method has been established. Moreover while the eco-efficiency of each home appliance is being improved, the increasing number and size of such home appliances may increase the overall environmental impact. This paper begins with describing a practical eco-efficiency (Factor X) indicator developed to evaluate environmentally conscious products or services. This indicator gives a rationalized relationship between their functional performance and environmental impacts. Next, the paper presents a brief case study of Factor X done in Japan that compared home appliances from 2003 with those from 1990 using such indicators. The number of home appliances used in a household increased 1.2 times from 65 to 79. However, GHG (greenhouse gas) emissions per year was 0.64 times the former amount, dropping from 8456 to 5383 kg–CO₂eq/year, and the new resources and discarded resources per year became 0.99 times the previous amount, dropping from 231 to 228 kg/year. Therefore, GHG Factor X was 1.9 and Resource Factor X was 1.2. Although based on a restricted evaluation model, these results quantitatively show the potential to improve functional performance (as evaluated by the number of home appliances) and at the same time reduce their environmental impacts (as evaluated by GHG emissions and new resources and discarded resources). These results also show that Resource Factor X is more difficult to improve than GHG Factor X. Improving Resource Factor X and establishing a sound material-cycle society requires not only technological innovation and reform of the social system, but also a significant change in people’s awareness.

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A Mg–Al layered double hydroxide (Mg–Al LDH) has been modified with aromatic anions by a coprecipitation technique. This method is based on the anion-exchange characteristics of the hydrotalcite-type compound which intercalates various anions, including anions of organic acids, in the interlayer. The Mg–Al LDHs are intercalated with 2-naphthalene sulphonate (2-NS⁻) and 2,6-naphthalene disulphonate (2,6-NDS²⁻) ions, which contain a naphthalene ring with one and two sulphonate (–SO₃⁻) groups in their structures, respectively. They are formed by the dropwise addition of a mixed aqueous solution of Mg(NO₃)₂ and Al(NO₃)₃ (Al/Mg mole ratio = 1/3) to a solution containing the individual organic anion at a constant pH of 10.0. The Mg–Al LDHs modified with aromatic anion are expected to recognize and selectively uptake hazardous aromatic compounds, such as bisphenol A, from aqueous solutions. The composite materials prepared were characterized by X-ray diffraction, FT-IR spectroscopy and chemical analyses.
2-NS⁻ was observed to be intercalated into the interlayer almost fully up to the accommodation expected based on the neutralisation of the positive charge of the host lattice. The intercalation of 2,6-NDS²⁻ was approximately 80% of the expected value, however. IR analysis results show that the organic anions are intercalated into the Mg–Al LDH without any significant change in their intrinsic structure.
The X-ray diffraction data suggest that the intercalation of the organic anions under consideration was accompanied by an expansion in the basal spacing of the LDHs. The X-ray diffraction patterns of the 2-NS⁻-modified LDH suggested the formation of two types of LDHs showing different basal spacing at higher 2-NS⁻ content. On the other hand, the 2,6-NDS⁻-modified LDH showed diffraction peaks, which corresponded to the basal spacing, with widely spreading peak angles and reduced intensity, suggesting the widely varying basal spacing of the Mg–Al LDH.

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Here we show a novel chemical vapor synthesis technique, which uses high-pressure hydrogen and produces needle-shaped single crystalline made of metal hydride of MgH₂. The principle of this method is based on the gas phase reaction of vaporized metal with high pressure hydrogen sublimating into solid metal hydride (Mg(g) + H₂(g) → MgH₂(s)). This can directly produce pure single-phased metal hydride of MgH₂, while the conventional solid-gas reaction (Mg(s) + H₂(g) → MgH₂(s)) can hardly produce high purity hydride. The X-ray spectrum of as-synthesized product was MgH₂ with rutile structure. The scanning electron micrographs showed the interesting figure of the product; needle-shaped nano fibers with diameter less than 500 nm and length larger than 100 μm. Transmission electron micrograph and related electron diffraction pattern provided that the needle-shaped product was single crystalline of MgH₂ growing into [1 0 1] direction, into which Mg-layers and H-layers are alternately stacked up. The results appealed a revolutionary productive route for metal hydride, which offers many benefits for simplifying the productive procedure, minimizing processing time, saving energy, and upgrading the product.

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Bioactive hydroxyapatite (HA)-coated implants plasma sprayed on Ti6Al4V substrates have been widely used in load-bearing applications because of their biocompatibility and their intimate contact with bone. The improvement of the characteristics of HA coatings is concerned. The purpose of this work was to evaluate corrosion behavior and bond strength of HA coatings after post-deposition heat treatment at 500–700°C. The results indicated that the heat treatment led to recrystallization of amorphous calcium phosphate of as-sprayed HA coatings. The reduction of layer defects associated with plasma-sprayed coatings and the enhancement of the resistance to corrosion took place after heat treatment. Bond strength of the heat-treated coatings was sensitive to the treatment temperature. It is concluded that the heat treatment at 600°C for 1 h in air, endowing with increased crystallinity and the reduced defects without significantly reduced bond strength, provided a better corrosion protection than the other two treatment temperatures.

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There has been an intensive effort in the industries in recent years to replace leaded solder with lead-free process in order to minimize the emission of toxic materials. However, leaded solder is still used in many cases where no alternative lead-free process is currently available. Leaded soldering of the wire terminals is one of the worst examples as it causes cross contamination of lead into the lead-free solder bath during the successive process. To avoid this problem, it is important to develop a new process of successfully removing polymer film coated on a copper wire. We have investigated the use of atmospheric pressure plasma as a solution for the polymer removal in conjunction with lead-free solder plating. The atmospheric plasma technology has some unique advantages compared with the conventional low pressure plasma processes such as low cost operation and high speed processing as the chemical reaction tends to be more enhanced at higher pressure. An atmospheric micro-plasma source was thus developed for this purpose and its high etching rate of more than 100 μm/min with fluorine gas mixture was demonstrated. Furthermore, it was found that the copper wires processed by this plasma could be readily plated with lead-free solder at low temperature of 250°C without any use of fluxes even at 168 h after removing the polymer film.

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The microstructure and corrosion behaviour of the thermite reaction coatings for the systems of Al–CuO–SiO₂, Al–Cr₂O₃–SiO₂, and Al–TiO₂–SiO₂ that produced by laser cladding on aluminium alloy 7075 have been studied. The results of the XRD analysis show that in all the three reaction coatings, α-Al₂O₃ and γ-Al₂O₃ phases were present together with various intermetallic phases and the corresponding reduced metal. A comparison of the polarisation curves of the untreated and the various coated specimens shows that except for the Al–CuO–SiO₂ system, the corrosion current density of the coated specimens was one order of magnitude lower than that of the untreated specimen, also a higher corrosion potential was obtained. The inferior corrosion resistance of the Al–CuO–SiO₂ system is attributed to galvanic corrosion occurred between the reduced metal, the intermetallic compounds and aluminium.

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