In-situ micro-Raman scattering spectra of LaNi_3.4Co_1.2Mn_0.1Al_0.3 metal hydride were observed in a hydrogen atmosphere at pressures up to 1 MPa using a specially designed micro-pressure cell. For the fresh surface created by cracking, broad components near 1600 cm⁻¹ and 2900 cm⁻¹ appear and grow in the depolarized Raman spectra as the pressure increases to the β phase region. In addition to this, sharp components appear near 3000 cm⁻¹ in the polarized spectra in both α and β phases. The sharp and broad components are assigned to oxides and vibration of hydrogen atoms in the metal hydride, respectively. On the other hand, characteristic Raman spectra rarely appear for the polished flat surface. These results indicate that the catalytic fresh surface area created by cracking plays an important role in the hydride formation.

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The effectiveness of Pd-coating on ZrNi against impurity gas exposure was examined. X-ray diffraction profiles revealed that the surfaces of plate and grain samples are readily covered with Pd by electroless plating. Mutual diffusion between the Pd-overlayer and the ZrNi substrate and PdZr formation took place by vacuum heating above 973 K. Deuterium recovery (DR) in a flowing argon carrier gas containing 5 ppm of impurity gases was examined using packed columns of bare ZrNi and Pd/ZrNi grains. Results indicate that the Pd-coating successfully extends the life time of ZrNi against impurity gases at low temperature below 473 K. Furthermore, no noticeable reduction in DR was found in Pd/ZrNi, whereas bare ZrNi loss its activity at 10 ks at 573 K.

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A higher order regular solution model developed previously by the authors has already been extensively applied in the prediction of the amorphous formation area of rapidly quenched ternary alloys. As only the chemical interaction among the randomly distributed substitutional atoms is considered, the original model can only be applied to calculate the mixing enthalpy of the substitutional metallic solid and liquid solutions. In the present study, the model has been extended to include the exchange interaction between the collinear magnetic moments of the atoms and the chemical interaction between the nonmetallic atoms on the interstitial sites and the ferromagnetic atoms on the regular sites. The extended model has been successfully applied to investigate the dependency of hydrogen solubility on temperature and magnetization in the transition metals Fe, Co and Ni near the Curie point.

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By using the simulated-annealing technique with a tight-binding molecular-dynamics, fully optimized structures of iron clusters are determined for the number of atoms, n=2–17. It is found that the clusters with sizes, n=6, 7, and 13, are relatively stable. Iron clusters show an icosahedral growth similar to rare gas clusters. HOMO–LUMO energy gaps are calculated, and electronic shell effects are absent. Additionally, by performing a self-consistent tight-binding molecular-dynamics calculations, we obtain fully optimized structures of positively- and negatively-charged iron clusters. Nearest-neighbor distance of positively- and negatively-charged iron clusters reveals an decrement and increment compared to that of the neutral clusters, respectively. These changes in the interatomic distances are mainly due to the changes in the number of HOMO electrons in anti-bonding molecular-orbitals.

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Ni₂MnGa alloys with relative density of 99.6% were obtained with a maximum pressure of 80 MPa and a maximum temperature of 1173 K applied in the Spark Plasma Sintering (SPS) process. Heat treatment was subsequently performed at 1073 K for 864 ks in vacuum with slow cooling. The martensitic transformation temperatures, M_s, M_f, A_s, A_f, were determined as 235, 220, 239 and 254 K respectively. Mechanical property comparisons of sintered alloys to arc-melted alloys were experimentally investigated by compression tests at room temperature. Sintered alloys show compressive ductility of 24% strain with transgranular cracking while arc-melted alloys only have 8% strain and both intergranular cracking and transgranular cracking. Furthermore, the sintered alloys possess higher yield stress and fracture strength.

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The standard electrode potential for Cu is 0.34 V and that of In is −0.34 V, which means that their deposition potentials are far apart, making the co-deposition difficult from a simple solution containing Cu and In ions. In order to bring these deposition potntials closer, a complex forming reagent of citric or EDTA is added to the CuSO₄–In₂(SO₄)₃ solution. The effect of these reagents was examined by linear sweep veltammetric measurement. An electrochemical deposition experiment of Cu–In alloy was conducted where effect citric acid or EDTA addition, current density and Cu concentration were examined.

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Vanadium-based BCC alloys are known to absorb a high amount of protium. But, they do not desorb absorbed-protium completely. This paper aims to clarify the effects of alloy composition and heat-treatment on the protium absorption-desorption properties of Ti-(0–35) at%V–Cr alloys.
A Ti–35V–40Cr alloy was chosen as the starting composition. The plateau pressure of the Ti–35V–(40+x)Cr (x=−3, 0, 3) alloys increased with increasing Cr content. For the alloys containing more than 15 at%V, a BCC phase was formed in the as-cast state, which was found to have an effective protium capacity of about 2.4 mass%H. However, a Laves phase was formed for alloys containing less than 10 at%V, which only had an effective protium capacity of about 1.8 mass%H.
The effect of heat-treatment on the microstructures and protium absorption-desorption properties of the Ti–35V–40Cr alloy were studied. It was found that the optimum condition for heat-treatment was annealing at 1573 K for 1 min. The Ti–35V–40Cr alloy heat-treated under this condition exhibited the highest effective protium capacity of 2.6 mass%H. This effective protium capacity is higher than any other reported values at 313 K. However, further annealing at 1573 K led to a decrease in protium capacity, which may result from an increase in the amount of a Ti-rich phase. A Ti–10V–55.4Cr alloy, which contained a Laves phase in the as-cast state, became single-phase BCC after heat-treatment. Even though the alloy contains only 10 at%V, this heat-treated alloy showed an effective protium capacity of 2.5 mass%H, which is higher than any other reported values for BCC alloys.

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By employing stress-strain constitutive relationships within Gilman-Johnston and Alexander-Haasen models, transient behavior of calculated stress-strain curves is examined in the light of Cottrell-Stokes law. It is pointed out that the incorporation of the interaction force between mobile and immobile dislocations are indispensable to satisfy Cottrell-Stokes law.

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Titanium aluminides (TiAl) with different magnesium contents of 0, 0.37, 1.84, 3.61 and 15.8 mol% were manufactured through the mechanical alloying and pulse discharge sintering process. The mechanically alloyed TiAl powders with different magnesium contents possessed similar X-ray diffraction profiles, corresponding to alpha titanium. The TiAl powders were sintered for a short sintering time of 900 s, and a complete transformation from the supersaturated alpha titanium structure to TiAl with small amount of Ti₃Al phase as well as nitride were confirmed. It was found that the content of Ti₃Al phase in the sintered material decreased with an increase in the magnesium content. While the TiAl alloy without magnesium addition showed a submicron structure with equiaxed gamma grains, the microstructure was coarsened by the addition of magnesium. With an increase in the magnesium content the density of the material decreased monotonically, which is attributed to the solution of light magnesium atoms to the TiAl structure and the decrease in the Ti₃Al phase content. Small amount of magnesium addition (0.37 mol%) increased the Young’s modulus of TiAl alloy, but further increases in the magnesium content decreased the Young’s modulus.

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Lorentz electron microscopy offers a very useful technique by which the magnetic domain structure of a thin film can be observed. In order to develop GMR materials with high sensitivity, it is desirable to understand the magnetic domain structure of the material. In this study, the magnetic domain structure of a series of NiFe/Au multilayer films (MLFs) with Au layer thickness between 1 nm and 4 nm has been observed using Lorentz microscopy. The MLFs showed a complicated domain structure, which contained twin walls and cross-tie walls in the MLFs. As the Au layer thickness increased so the ferromagnetic coupling between the NiFe layers decreased resulting in a more complex domain structure. In-situ magnetizing experiments showed that magnetic domain wall motion was the dominant mechanism for reversing the direction of magnetization. It is believed that reversal of the magnetization in the MLFs with thick Au layers was greatly affected by the structural defects in the films.

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The compositional dependence of the electromagnetic wave absorption properties of Barium M-type ferrite, in which a mixture of Ti and Mn were substituted for Fe, was investigated. Single phase M-type structure was obtained for the BaFe_12−x−yTi_xMn_yO₁₉ sintered samples with compositions x<2.5 and y<2.5, and Mn substitution allowed the single phase to form at higher Ti contents. It was found that the natural resonance frequencies (f_r) of these sintered samples can be controlled in the range 3.85 to 60.18 GHz, by changing the Ti and Mn content. Almost all of the samples in the M-type single phase region impedance-matched and exhibited a minimum reflection loss (R.L.) less than −20 dB at matching frequencies (f_m), with matching thicknesses (d_m) smaller than 4 mm, which demonstrates that these ferrites can function as thin electromagnetic wave absorbers in this frequency range. Some samples outside this single phase region with a high Mn and Ti content also impedance-matched, however the impedance matching is more sensitive to changes in Ti content than in Mn content. As a result, f_m, and d_m values varied from 33.25 to 3.75 GHz and from 0.27 to 3.80 mm, respectively.

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Shear bands (SBs) in cold-rolled austenitic stainless steel 310S have been investigated by using transmission electron microscopy (TEM). Shear Bands appear in the region of twin-matrix lamellae which have already developed at moderate strain. Inside the shear band, fine grains are observed, and the shape of each grain is somewhat elongated along the shear direction. These features found in 310S are similar to those observed in materials with very low stacking fault energy such as α-brass. Selected area diffraction patterns obtained from a SB reveals that local orientations inside the SB are distributed between those in the matrix and the twinning region. Using dark field images of the SB, it is shown that some of the misorientations of neighboring grains in the SB reach nearly 20 degrees. Based on these observations, the formation mechanism of SBs is discussed.

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The effect of martensite aging in Ti–Pd and Ti–Pd–Ni high temperature shape memory alloys was investigated by DSC measurements and TEM observations. It is shown that the aging effect is strongly dependent on the alloy composition. Ti₅₀Pd₅₀ and Ti₅₀Pd₄₀Ni₁₀ alloys exhibit a pronounced martensite aging effect, but no obvious aging effect was observed in Ti₅₀Pd_50−xNi_x (x≥20) alloys. The magnitude of the aging effect in the Ti₅₀Pd₄₀Ni₁₀ alloy is much greater than that in the Ti₅₀Pd₅₀ alloy and the composition dependence of the aging effect is discussed. Besides, a curious feature of martensite aging was observed, i.e., A_s and A_f temperature increase does not saturate even after relatively long time aging. This is considered to be due to the recovery·recrystallization of martensite during aging.

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Indium zinc oxide (IZO) thin films sputter-deposited on glass substrate were investigated for use as pixel electrodes of thin-film-transistor liquid-crystal display (TFT-LCD) applications. The experiments revealed that IZO thin film is suitable for use in high-performance TFT-LCDs with respect to its electrical and optical properties, and its etching performance. Cross-sectional transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses indicated that the IZO film remains in an amorphous state after annealing in vacuum or in an N₂-added atmosphere, but that its electrical and optical properties are changed by annealing in an N₂-added atmosphere. After the latter treatment, the film’s resistivity increased to about 3 times that of an IZO film annealed in vacuum; however, we found a novel transparent conductive thin film, which has over 90% transparency within the infrared range (800–3200 nm) and a resistivity of about 1.2 mΩcm. Depth profile analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS) revealed a difference of chemical structure in the two films after annealing under different conditions.

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Initial growth of gold and aluminum nanoclusters on highly oriented pyrolitic graphite (HOPG) or amorphous carbon are investigated using scanning tunneling microscopy. A 2-dimensional hexagonal lattice is formed on HOPG. Such 2-dimensional nanoclusters are oriented to the direction rotated by 30°C from graphite lattice, and the atomic distance of the nanoclusters is estimated to be 0.424 nm. The nanoclusters are linked with each other along the directions mentioned above when deposited atoms migrate on the HOPG surface at room temperature.

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Mechanical alloying (MA) of elemental powder mixtures, with an Fe-9.85 mass%N alloy powder as the nitrogen source, of the composition of Cr–Mn type stainless steels was carried out in an Ar atmosphere using a conventional planetary ball mill. In the MA processing of Fe_79−x−yCr₁₈Mn_yMo₃N_x (mass%) (x=0.45 and 0.9; y=5–18) material, the MA samples with x=0.9 is austenitized down to near y=8, whereas the MA samples with x=0.45 begin to austenitize near y=11. Fe_71.1−zCr₁₈Mn₁₀Mo_zN_0.9 MA samples with Mo contents (z) in excess of 3% make the austenite phase, formed in the MA powder materials, less stable. Using a hot-rolling technique tried in the current study, the compact sample of Fe_68.1Cr₁₈Mn₁₀Mo₃N_0.9 MA powder material was fully densified, retaining the nanostructure. Addition of AlN to the MA material of Fe_68.1Cr₁₈Mn₁₀Mo₃N_0.9 made it possible to suppress the grain growth in the compact sample, to a considerable extent, during hot-compaction using the rolling process.

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Monte Carlo simulation of an FCC lattice-gas model is carried out to study order-disorder phase transitions. To study an actual Cu–Au alloys as quantitatively as possible, a Finnis-Sinclair-type potential, which has been used widely for molecular dynamics (MD) simulations, is mapped onto the FCC model by using the potential renormalization technique proposed by one of us. Using this renormalized potential, we find that the linear expansion coefficient of Cu and Au crystals and the transition temperatures are greatly improved when compared with the case of using the MD potential directly on the lattice.

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SrTiO₃ is used as a substrate for thin films of superconducting oxides. From this point of view, it is important to investigate lattice defects in as-grown or as-annealed bulk SrTiO₃ crystals. In this paper, we aimed at distribution of dislocations in SrTiO₃ single crystals under no external force. We examined two groups of crystal plates of which lapped faces were (001) and (011). We checked the defect distribution throughout the crystals by X-ray topography (reflection method). X-ray topographs showed that the (011) crystal plates had more defects than (001) plates. Then microscopic observation by transmission electron microscopy (TEM) revealed that many dislocations existed in the point where thick line image contrast was observed by X-ray topography in the (011) plate. Most of them had ⟨100⟩ type Burgers vectors. On the contrary, it was showed that very few dislocations were dispersed throughout the (001) crystal plates by X-ray topography. It was revealed that these dislocations did not always exist alone and had ⟨100⟩ type Burgers vectors by TEM.

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Charge/discharge characteristics of Mg₂Ni electrodes were examined by focussing attention on the influence of surface modification by heating in argon. The initial activation was significantly easier for the electrodes heated at 550°C than un-heated ones. The surfaces of electrodes became porous by the heating because of the evaporation of magnesium. A MgO layer was formed during the heating. The improvement of charge/discharge characteristics by the heating was ascribed to the increase in the specific surface area and the porosity of the oxide film, and to the formation of MgNi₂ and nickel phases which should act as the local reaction sites for hydrogen during the charge and discharge processes.

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The structural transformation from fcc to bcc was modeled using a potential-change procedure and a constraint method in the molecular dynamics calculation. To model the transformation, inter-atomic potentials were changed before and after the transformation. To obtain a definite image of the elementary event of nucleation, the following was investigated: (a) how individual atoms move and (b) how an orientation relationship forms during the formation of a crystal. The elementary event of the structural change consists of a contraction, an expansion and a rotation. The contraction and the expansion relate to the structural change and are described in terms of a Bain deformation. The rotation relates to the development of an orientation relationship. The structure changes at an early stage of the nucleation process. On the other hand, the orientation relationship develops gradually during the process.

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In order to increase the capacity of miniaturized button-type batteries, the thickness of the Cu/18Cr–8Ni–Fe(SUS304)/Ni clad metals which are applied to the anode cases should be reduced. Therefore it is required that the clad metals have higher strength and excellent drawability. We found that the clad metals had good properties (high tensile strength and small planar anisotropy) which the SUS304 single sheet did not have, as a result of examination of the rolling and annealing process. The texture formation of the clad metals was investigated, and the influence of texture on the r-values is discussed in this research. The SUS304 in the clad metals with good properties has lower Goss and higher brass orientation density than the SUS304 single sheet under the 25% finish rolled condition after annealing. The orientation densities on α- and β-fibers of SUS304 and Cu in the clad metals are qualitatively similar to each other, and different from those of the SUS304 single sheet. This suggests that the characteristic texture of SUS304 in the clad metals is formed through the influence of the Cu layer. The planar anisotropy of r-values was calculated from ODF to inquire into the effect of the texture on r-values by using Taylor’s full constraints model and relaxed constraints model. This result corresponded well to the measured r-value, especially in the relaxed constraints model.

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Superplastic behavior of a commercial magnesium alloy, AZ61, has been investigated. Tensile tests were carried out at temperatures ranging from 573 to 673 K and strain rates ranging from 10⁻⁵ to 10⁻³ s⁻¹. Superplastic behavior was observed in the low strain rate range and, especially, a maximum elongation-to-failure of 461% was obtained at 648 K at a strain rate of 3×10⁻⁵ s⁻¹. The alloy showed a high strain rate sensitivity exponent of 0.5. Inspection of the specimen surface after deformation revealed direct evidence for grain boundary sliding (GBS). In addition, the distribution of misorientation angles was essentially unchanged during superplastic flow. From these results, it was concluded that the dominant deformation mechanism was GBS.

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Formation and evolution processes of microstructure of Mo–Al alloys retarded by addition of 10 at%Ti are studied through various heat treatments. Fine acicular Mo₃Al precipitates are observed inside a grain for a specimen quenched at 1673 K as an initial stage of the eutectoid decomposition of bcc phase. It suggests that there is a crystallographic orientation relationship between the bcc matrix and A15 precipitates. By changing heat treatment conditions, fraction of fine lamellar structure decreases and spheroidized area increases. Subsequent aging treatment at lower temperature also provides the spheroidized structure. A coarse equiaxed structure is observed for a specimen quenched at 1673 K then aged at 1173 K.

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The microstructural evolution during the equal channel angular (ECA) pressing process of an α+θ′ two-phase Al-1.7 at%Cu alloy has been studied by transmission electron microscopy (TEM). The θ′ precipitates are severely deformed after the first pass of ECA pressing that gives rise to a strain of ε∼1. After 8 passes of the ECA pressing, most of the θ′ precipitates are dissolved and the nearly single phase of α with a fine grain size of approximately 500 nm is obtained. When the single phase ultrafine grain microstructure which is obtained from a supersaturated Al-1.7 at%Cu is aged for 24 h at 100°C, precipitation of the equilibrium θ phase is observed along the grain boundaries, whereas only GP zones are formed in the undeformed specimen. This suggests that the grain boundaries in the ultrafine grained microstructure provide heterogeneous nucleation sites for the θ precipitates. The supersaturation required for precipitation of the GP zones is lost quickly by diffusion of Cu to the grain boundaries when a larger strain is imposed by ECA pressing.

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Intermetallic compound TiAl-base composites have been prepared by the hot isostatic pressing (HIP) reactive sintering technique. These composites have been synthesized from a powder mixture of titanium, aluminum and boron nitride, and contain Ti₂AlN and TiB₂ strengthening particles. Nearly spherical particles of Ti₃Al and Ti₂AlN of about 20 μm in diameter have been embedded in the TiAl phase. The composite has been found with a dual phase matrix structure. The Ti₂AlN phase is composed of about 300–500 nm grains and includes dispersion of nano scaled TiB₂ particles (about 50–100 nm). Both compression tests and hardness measurements have revealed that this composite material attains higher strength as compared with non-reinforced TiAl. The insufficient bending ductility, however, hinders its bending fracture strength at ambient temperature.

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Cracks were formed along grain boundaries and along deformation bands in the interior of a grain in copper bulk bicrystals which had been compressed at room temperature, and then annealed in a vacuum at 823 K without unloading. It is considered that the cracks along grain boundaries and deformation bands were formed by strain induced premelting; when localized regions with high dislocation density are formed close to grain boundaries or deformation bands, the regions may melt at temperatures of approximately 0.5T_M (T_M: the melting point in Kelvin). Premelting cracks along deformation bands were found for the first time in this study. It was found that the development of premelting cracks was closely related to the duration of the compressive load without a large drop during the heating process. Various experimental parameters which affect the formation and development of premelting cracks are discussed.

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Thermal conductivity of isotopically enriched (93.2 at% ¹⁰B and 6.8 at% ¹¹B) and natural (19.8 at% ¹⁰B and 80.2 at% ¹¹B) β-rhombohedral boron crystals has been examined by a steady heat flow method. The maximum value of thermal conductivity, 570 (W/mK) at 40 Kelvin of ¹⁰B enriched crystal is the largest value of boron whose crystal structure has a rhombohedral type. Experimental result indicated that isotopic enrichment made the phonon-mean free path longer because of reduction of phonon scatterer. Theoretical curve calculated thermal conductivity by the Callaway model agreed with the experimental curve around the temperature range of the maximum value.

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The influences of the interfacial reaction on the microstructure and bond strength of the SiC/Cu joint friction-bonded with a Nb intermediate layer have been investigated mainly by TEM observations. It has been found that the reaction at the joint interface proceeded during the heat treatment even at temperatures below 800 K to form reaction layers ∼100 nm thick, which caused serious degradation of the joint strength. An attempt is made to thermodynamically explain the evolution of the interfacial microstructure caused by the reaction during the heat treatment.

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Rod shape intermetallic TiAl is developed by the method of mechanical alloying (MA) followed by pulse discharge sintering (PDS) process for the potential application in the automotive valves. Sintering of powder element mixture, instead of mechanically alloyed powder, was employed for the manufacturing of rod shape TiAl for comparison. The sintered TiAl rods were found to be homogeneous both in density and in microstructure in the axis direction. The effects of alloys’ composition and sintering time on the microstructure and mechanical properties were also investigated. This work indicated that rod shape TiAl alloys with thin cross section could be successfully sintered with this process in which uniaxial pressure was applied. The fracture strength of TiAl alloys made by MA-PDS method was found to be much higher than that of sintered elemental compact.

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This paper reports a technique that fabricates a magnetically graded material in which the saturation magnetization varies linearly as a function of distance. An initially wedge-shaped 304 stainless steel was rolled into a rectangular cross section. The saturation magnetization curve as a function of rolling ratio has a positive curvature. Since the rolling ratio distribution showed a negative curvature, it was possible to achieve a nearly linear magnetic gradient along the specimen. Furthermore, it was found that the hardness also varied gradually in the deformed specimen, suggesting that the technique presented in this work can fabricate a functionally graded material not only in magnetic properties but also in mechanical properties.

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The phase equilibria in the zirconia-rich part of the ZrO₂–Y₂O₃–MnO_t ternary system have been investigated at 1673 K in air by high temperature X-ray diffraction. The three phases, the tetragonal ZrO₂ phase, the fluorite-type cubic ZrO₂ phase and the Mn₃O₄ phase, have been detected without any compound. The phase boundaries have been intensively examined using the relation between the lattice parameter and composition. The solubility of MnO_t became larger with increasing Y₂O₃ concentration. In the ZrO₂–MnO_t binary system, 5.4 mol%MnO_t is soluble in ZrO₂, while in the ZrO₂–Y₂O₃–MnO_t ternary system, 10.3 mol%MnO_t dissolves into ZrO₂-6 mol%Y₂O₃. For the ZrO₂-3 mol%Y₂O₃ with dissolved MnO_t, the two phases of the tetragonal ZrO₂ solid solution and the fluorite-type cubic ZrO₂ solid solution are transformed to the single phase of the fluorite-type cubic solid solution as the MnO_t concentration increased. For the ZrO₂ with dissolved MnO_t, however, the single phase of the tetragonal solid solution does not transform even though MnO_t dissolved to its solubility. The transformation caused by the dissolution of MnO_t and the solubility of MnO_t in ZrO₂–Y₂O₃ system were discussed in reference to the cationic radius of the Mn ions.

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The Griffith concept of energy equilibrium for brittle mode I crack propagation was extended to mode II and combined mode I-II crack extensions. First, the maximum energy release rate for an infinitesimally kinked crack extension under combined mode I-II loading analyzed by Kageyama and Okamura was successfully expressed by a combined mode stress intensity factor. Second, the ratio between mode I and mode II fracture energy rates was estimated from the areas of the frontal process zone estimated from the area enclosed in the iso-stress contours of both the maximum principal stress and the maximum shear stress. Third, those considerations led to a predicted K_IIC⁄K_IC ratio of 1.20, which was quite near the experimental results of 1.1 to 1.3 obtained earlier. Finally, the combined mode I-II fracture criterion was formulated by the same technique, and the predicted criterion coincided well with Singh and Shetty’s empirical criterion.
The fracture toughness values of modes I and II, and the combined mode I-II criterion for polycrystalline alumina were also estimated experimentally using a disk method. The estimated result of K_IIC⁄K_IC ratio was 1.17, which was very close to the predicted value of 1.20. The experimentally assessed combined mode fracture criterion was closely related to the predicted one.

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This paper aims to study the influence of tempering on the mechanical properties of austempered ductile iron. A modified austempering treatment was carried out to obtain a microstructure mixture of ausferrite and tempered martensite by stopping the austempering reaction before stage 1 reaction was completed, and resuming tempering at 473 K for 7.2 ks after cooling to room temperature. The change in the microstructure and the related changes in mechanical properties of ADI after tempering were investigated. The results show that tempering at 473 K after austempering decreased the sensitivity of mechanical properties to austempering conditions. Independent of austempering temperature, tempering at 473 K also led to significant improvement in mechanical properties with increasing martensite content. Strength and toughness could be improved to exceed the maximum values obtained without tempering, and these strengthening effects were particularly obvious at martensite content below 5%. With tempering at 473 K, the required austempering time for obtaining the maximum values of mechanical properties could be shortened from 10.8 ks without tempering to 1.8 ks with tempering, and the effective austempering time interval was also extended.

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Aluminium-copper of (99.99%) high purity eutectic alloy was melted in a graphite crucible under vacuum atmosphere. This eutectic alloy was directionally solidified upward with a constant growth rate V, and different temperature gradients G, and also with a constant temperature gradient and different growth rates in the Bridgman type directional solidification furnace. The lamellar spacings λ_E were measured from both transverse section and longitudinal section of the specimen. The undercooling values ΔT were obtained by using growth rate and system parameters K₁, K₂. It was found that the values of λ_E decreased as V, G and GV values are increased. The relationships between lamellar spacing λ_E and solidification parameters, V, G and GV were obtained by Least squares analysis. Bulk growth rate λ²_EV was determined by using λ_E values for both the transverse section and the longitudinal section. The experimentally obtained values found were in good agreement with theoretical values.

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Quaternary interdiffusion experiments of Al-rich α Al–Zn–Mg–Cu alloys have been performed in the temperature range from 755 to 833 K. The concentration profiles indicate that the diffusion distance of Cu is shorter than those of Zn and Mg in the solid solutions. The direct interdiffusion coefficients \ ildeD_ZnZn⁴, \ ildeD_MgMg⁴ and \ ildeD_CuCu⁴ are positive, and indirect coefficients are negative. The impurity diffusion coefficients of Zn (or Cu) in Al–Cu (or Zn)–Mg alloys can be expressed by the following equations.
D_{Zn(Al–1.15Cu–2.01Mg)}^*=3.9×10⁻⁵exp(−124kJ mol⁻¹⁄RT⁻¹)m²⁄s,
D_{Cu(Al–3.37Zn–2.75Mg)}^*=5.7×10⁻⁵exp(−132kJ mol⁻¹⁄RT⁻¹)m²⁄s.
The ratio values of indirect to direct diffusion coefficients suggest that attractive interactions of Zn–Mg, Zn–Cu and Cu–Mg atoms exist in the Al–Zn–Mg–Cu alloys.

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High-temperature deformation behavior of high-purity polycrystalline alumina (the mean grain size is about 6 μm) prepared with no sintering additives has been investigated through a series of compression tests. In the testing temperature range from 1400 to 1600°C, the alumina can be deformed plastically at a lower strain rate, while it fails without plastic deformation at a higher strain rate. The ultimate stress decreased with the testing temperature and increased with the strain rate. The strain rate sensitivity of the flow stress is about 0.6 and the apparent activation energy is almost consistent with that of grain boundary diffusion of aluminum ion in the plastic deformation at the lower strain rates. In the specimens deformed at low strain rates, stress-enhanced grain growth and nucleation of cavities at triple points of grain boundaries were observed during the plastic deformation. The increase in area fraction of the cavity is proportional to the strain. It may be considered that the cavities nucleate and grow at the triple point by grain boundary sliding without a sufficient accommodation process.

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The texture and the texture evolution with annealing and deformation corresponding to the tetragonal second phase Al₃CaZn (≈20 vol%) of the superplastic Al-5%Ca-5%Zn alloy has been studied. In the as-received condition, the main texture component is comprised by crystallites in which the c axis tends to be aligned with the normal direction to the rolling plane (ND); i.e. a fiber texture. After annealing, the particles spheroidize and increase in size. With increasing time of annealing, the texture also strengthens and sharpens, indicating that Ostwald ripening is a selective growth process. However, with deformation both under optimum and non-optimum superplastic conditions, the fiber texture is destroyed. The fact that no significant decrease in the maximum texture intensity is observed, suggests that crystallographic slip within second-phase particles, in addition to grain boundary sliding, also takes place.

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High flexural strength exceeding 4000 MPa combined with sufficient deflection was found to be obtained in a cast bulk glassy Zr₅₅Al₁₀Ni₅Cu₂₉Nb₁ alloy consisting of crystalline regions with a size of 2 to 6 nm embedded in a glassy matrix. The phase with the fine mixed structure was named as a nanocrystalline glassy phase and produced by the combination of the following two effects; (1) metallurgical effect by the addition of Nb which enables us to form a supercooled liquid including homogeneous crystalline clusters resulting from the positive heat of mixing for Nb against Zr, and (2) the squeezing casting effect which enables us to form a bulk amorphous alloy keeping the specialized structural feature in the supercooled liquid. The nanocrystalline glassy structure was characterized to lie in a transient stage from the glassy to nanocrystalline phases and the structural feature was identified by high-resolution transmission electron microscopy.

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Structural and soft magnetic properties were investigated for a bulk glassy Fe₇₀Al₅Ga₂P_9.65C_5.75B_4.6Si₃ alloy in a ring shape form with an outer diameter of 10 mm, an inner diameter of 6 mm and a thickness of 1 mm prepared by copper mold casting. The bulk sample composes of an amorphous single phase. The supercooled liquid region (ΔT_x) defined by the difference between the crystallization temperature (T_x) and glass transition temperature (T_g) for the bulk glassy alloy is about 60 K, being in agreement with that of the corresponding amorphous alloy ribbon. Saturation magnetization (σ_s) and Curie temperature (T_c) for the bulk sample are about 1.2 T and 620 K, respectively, both of which agree with those of the melt-spun ribbon. Furthermore, the maximum permeability (μ_max) and the coercivity (H_c) for the bulk glassy sample in as cast state are about 110000 and 2.2 A/m, respectively. These excellent soft magnetic properties are presumably due to a higher degree of structural homogeneity resulting from its high glass-forming ability. It is concluded that the good soft magnetic properties combined with high glass-forming-ability and castability of the Fe–Al–Ga–P–C–B–Si glassy alloy hold promise for its development as a future engineering magnetic material.

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