We constructed a partial isothermal phase diagram including a decagonal (d-) phase in the Al–Ni–Co system and determined the composition of the liquid in equilibrium with the stoichiometric d-phase. The d-phase is formed through a peritectic reaction between the B2 phase and the liquid phase. A seed d-phase prepared by selecting an optimum composition of the liquid phase was used for growing a large-scale d-quasicrystal by the Czochralski method. As a result, we have product a single decagonal quasicrystal with the size of 60 mm in length and 1 to 7 mm in diameter and the mean composition of Al_72.2Ni_12.1Co_15.7.

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Zener-Smith proposed the original relation R=4r⁄3f_ν in 1948, where R and r are the mean radii of the matrix grains and dispersed particles, and f_ν is the volume fraction of dispersed particles. They derived the relation under the assumption that the configuration of the grain boundary was independent of particle distribution. In the present work a modified relation R=4r⁄3f_ν^2⁄3 has been obtained by assuming that (1) the grain boundary is roughened by particle pinning, and (2) the amplitude of the roughness is λ⁄2, where λ is the inter-particle distance. Experimental data on the radii of austenite grains and the dispersed cementite particles in high C high Mn steels are shown to agree well with the modified relation.

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Zirconium nitride precipitates, ZrN, were produced by internally nitriding single crystals of niobium containing various (small) amounts of zirconium, at 1473 K in nitrogen gas at a partial pressure of about 5×10⁻⁵ Pa. The structural changes that occurred during annealing treatments after nitridation were investigated using transmission electron microscopy. Electron diffraction patterns show that ZrN particles have the Bain type orientation relationship with the matrix.

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Surface relief effect accompanying bainitic transformation in an Fe–C–Si–Mn alloy has been investigated by scanning tunneling microscopy (STM). It was discovered that a lower bainite subunit in an Fe–C–Si–Mn alloy is composed of sub-subunits, whose surface reliefs are tent-shaped, i.e. of a non-invariant plane strain (IPS) type, which is inconsistent with shear mechanism. The sub-subunit is idiomorphic, the height of its relief is 60–140 nm, and its maximum shape deformation is ca. 0.23. Multi-layer structure of bainite and effect of composition in steels on the ultrafine structure of lower bainite can be interpreted by the sympathetic nucleation-ledgewise growth mechanism.

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The introduction of large amounts of hydrogen into low-carbon steel specimens by cathodic polarization produces hydrogen damage such as blisters, microcracks and dislocations. Hydrogen exists in the specimens as atoms dissolved in the iron lattice, as atoms trapped at lattice defects such as dislocations, and as gas precipitated in void defects such as blisters and microcracks. Hydrogen detected by electrochemical permeation in annealed specimens is one dissolved in the lattice, and the majority of hydrogen detected by glycerol displacement is the precipitated molecular hydrogen. In annealed specimens, a single peak is observed in the thermal evolution spectrum. This peak originates from the evolution of precipitated hydrogen, and the peak temperature depends on the specimen thickness, hydrogen concentration and heating rate. In cold-rolled specimens, two peaks are observed. The lower temperature peak originates from the evolution of precipitated hydrogen and the higher temperature peak from the trapped hydrogen.

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An electron microscope technique has been employed to investigate the boundary-dependent intrinsic capability of sliding of [001] symmetric tilt boundaries in Cu below 573 K. The sliding has been detected by measuring a change in the direction of moiré fringes of α–Fe–Co particles on the boundaries in aged Cu–Fe–Co bicrystals. The magnitude of sliding is less than 1 nm. The pre-exponential factor η₀ and activation energy Q of grain-boundary viscosity against misorientation angle curves are similar to the boundary energy against misorientation curve. A higher-energy boundary slides more easily with a lower viscosity and is described by a larger value of η₀ and a smaller value of Q. The misorientation dependence of the diffusivity of Bi along the same boundaries of Cu has also been examined. A close correlation is found between the viscosity and the diffusivity of the boundary. The higher is the boundary diffusivity, the lower is the boundary viscosity. It is suggested that the sliding process is controlled by boundary diffusion.

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The results of experimental investigations of reduction of magnetite pellets with different granulations of added charred coal, under nitrogen atmosphere, in the temperature range of 1273 to 1384 K, are given in this paper. The kinetic parameters, activation energy and preexponential factor have been determined, which enabled defining of the rate constant and charred coal granulation’s dependencies upon temperature and dependence of the reduction course upon time, temperature and charred coal granulation.
Also, the dependence of reduction activation energy on specific surface area and average grain diameter of added solid reducer-charred coal are presented.

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The solubility of carbon in liquid silicon equilibrated with silicon carbide was determined in the temperature range from 1723 to 1873 K. Silicon was melted in a silicon carbide crucible with an Ar-CO mixture gas flowing. Carbon in silicon was analyzed by the combustion-IR absorption method. The temperature dependence of the carbon solubility in liquid silicon can be represented by the following equation:
log(C_C⁄mass%)=3.63−9660⁄T(±0.02) (T: 1723-1873 K)
The carbon solubility at the melting point of silicon was calculated to be 79 ppm (9.1×10¹⁸ atoms·cm⁻³). The level of oxygen impurities in the melt was much lower than that of liquid silicon equilibrated with solid silica. The standard Gibbs free energy change for carbon dissolution in liquid silicon can be represented as:
C(s)=C(1 mass%, in liquid silicon)
ΔG°=7.20×10⁴−11.4TlogT+6.20T (J)

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The coalescence of aluminum and aluminum alloy drops in molten salt flux was observed in different salt fluxes as a function of time. Salts based on equimolar NaCl–KCl with addition of other metal chlorides or metal fluorides were used. All salts showed the ability to coalesce metal drops into one drop, but time taken for complete coalescence was different for different salts. Metal drops are covered with oxide film, which hinders their ability to coalesce into one metal drop. Thus, the coalescence ability of any salt depends on the efficiency of oxide removal by the salt. Removal of oxide layer from aluminum surface by equimolar NaCl–KCl and equimolar NaCl–KCl containing 5 mass%NaF was observed by interference microscopy. It was found that the oxide layer was not removed by equimolar NaCl–KCl, while it was removed by equimolar NaCl–KCl containing 5 mass%NaF. Coalescence ability of salt is related to weight loss of metal in salt and interfacial tension between metal and salt.

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Angle resolved X-ray photoelectron spectroscopy (AR-XPS) has been used for characterizing native oxide layers formed on the surface of ultra high-purity iron and copper by exposure to air at room temperature. Thickness of an oxide layer formed on the surface of ultra high-purity iron is found to be thicker than that for ultra high-purity copper in the initial stage of oxidation and almost unchanged by air exposure time. On the other hand, thickness of an oxide layer formed on ultra high-purity copper is found to increase with increasing air exposure time. These results are consistent with spectral information for ultra high-purity iron and copper exposed to air; the chemical state of Fe in the surface of ultra high-purity iron is almost independent of exposure time, whereas the chemical state varies in the surface of ultra high-purity copper by exposure for a long term.

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Laser surface-alloying method was applied in order to develop functional gradient Inconel/Steel alloy material. Inconel 690 sheet was placed on a steel substrate, and then a series of high power CO₂ laser beams was irradiated in order to make a homogeneous alloyed layer. Simultaneous compositional gradients of two different kinds of alloying elements (Cr and Ni) were investigated in this material, and experimental values were compared with the calculated values. In order to determine the microstructure, phase and composition of each alloyed layer, SEM, XRD and EDS were used. Sequential repetition of laser surface-alloying treatments up to 4 times resulted in about 3 mm layers of fair compositional gradients from 21%, 40% and 39% to 0%, 0% and 99% for Cr, Ni and Fe in this material. Since volume changes were different between the alloyed region and the heat-affected substrate region, oblique cracks were formed at the far side of the boundary region.

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The effect of solidification rate on the solidified structure, solute segregation and microstructures such as carbide, γ′⁄γ eutectic, γ′ phase and dendrite arm spacing was experimentally investigated employing a method of partially directional solidification and subsequent quick quenching. Three types of the solidified structure were identified: cellular, cellular-dendritic and developed dendrite-type, and the width of a mushy zone was narrowed when solidification rate increased from 2.5 μm/s to 125 μm/s. The carbide morphologies were affected by both solidified structure and solidification rate, it formed into bar-type in the cellular structure, and Chinese script-type in the dendrite structure. The increase of solidification rate caused a lot of γ′⁄γ eutectic and the change of γ′ phase from cubic into cubic-round. The dendrite arm spacing decreased and the segregation of Cr, Al, Co, Mo, Ti was alleviated with increasing solidification rate.

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Thermoelectric modules assembled with nickel or copper electrodes and bismuth telluride system semiconductors prepared by mechanical alloying were evaluated for long exposure time dependence.
Modules exposed at temperatures of 400 and 473 K from 1 to 1000 h in air were measured for thermoelectric motive forces and internal resistances. The properties of nickel and copper electrode modules did not change up to 400 K. However, the internal resistance increased with increasing exposure time at 473 K. This was because the tin element in the soldering material was diffused in the bismuth telluride system semiconductors, making many voids in the junction layer. Furthermore, these results showed that the maximum output could be effectively evaluated using the Larson-Miller parameter (C=15.2).

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Hard magnetic Nd₆₀Fe₃₀Si₁₀ amorphous ribbons with large thicknesses up to 107 μm were prepared by melt spinning. The hard magnetic properties of this alloy increase with increasing ribbon thickness to 107 μm, and the largest values of remanence, coercivity (iH_c) and maximum energy product (BH)_max are 0.15 T, 412 kA/m and 3.8 kJ/m³, respectively. The main feature of this amorphous alloy is that the hard magnetic properties with high iH_c are obtained in the melt-spun amorphous state without crystallinity. The combination of the large glass-forming ability and hard magnetic properties is important for the future development of hard magnetic bulk amorphous alloys.

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