Ostwald ripening in solid matrices is studied theoretically considering the stress around dispersed particles induced by the volume gap.
Under the condition that the diffusion in the matrix compensates the volume gap, a ripening rate equation is derived as follows:
(Remark: Graphics omitted.)
The equation is a generalized one for multi-component system and covers all conventional formulas. Under the condition that the creep deformation takes place to compensate the volume gap, the equation is given as follows:
(Remark: Graphics omitted.)
The results of calculation have revealed that the creep deformation is more dominant than the iron diffusion to compensate the volume gap for cementite coarsening in ferrite below 973 K.

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Interdiffusion coefficients in Ag–Zn α phase in the temperature range between 823 and 1023 K have been determined by Sauer and Freise analysis using solid-solid diffusion couples consisting of pure silver and a 20 at%Zn–Ag alloy. From the Sauer and Freise’s and the Darkens’s equations, a simple expression for the ratio of the intrinsic diffusivities with respect to the mole-fixed frame of reference can be derived. Using the expression, the ratio D_Zn^N⁄D_Ag^N at 1023 K has been determined. With the aid of the ratios D_Zn^N⁄D_Ag^N determined in this investigation and the ones previously determined by the vapor-thin plate diffusion couples, the vacancy flow factor, G, in the infinitely dilute state has been estimated to be −0.55 at 1023 K. By combining the value for G with the known solute enhancement factor for solvent diffusion the correlation factor for impurity diffusion of Zn in Ag has been evaluated.

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From the viewpoint of fundamental study of steelmaking, the direct determination of the structure and composition of niobium nitride in equilibrium with liquid Fe–Nb–N alloy has been attempted by means of high temperature X-ray diffraction technique. X-ray analysis has also been carried out at room temperature for niobium nitride powder extracted from the solidified alloy ingot.
It was found from a high temperature X-ray diffraction pattern that the niobium nitride equilibrating with liquid Fe-(11.5–14.3) mass%Nb–N alloy at 1813 K under an atmospheric pressure of nitrogen belonged to δ phase with fcc structure. The phase of niobium nitride precipitated in liquid Fe-(11.5–14.3) mass%Nb–N alloy seemed to be morphologically invariant during the cooling and solidification at the rate of 3–5 K/s or 0.2–0.5 K/s.
The lattice parameter of niobium nitride was determined to be 0.4385 nm at room temperature, and its composition was estimated to be Nb_1.1N from the relation between the lattice parameter and the ratio N/Nb. Provided that the composition of niobium nitride does not change in the course of cooling and solidification, the niobium nitride forming reaction in liquid Fe-(11.5–14.3) mass%Nb–N alloy at 1813 K under an atmospheric pressure of nitrogen is expressed as follows:
1.1Nb+N=Nb_1.1N(s).

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The phase equilibria in the Ni–Fe–O system were established at several temperatures between 1153 and 1213 K by varying the oxygen partial pressures. Besides thermogravimetric and quenching methods, electromotive force (EMF) measurements composed of calcia-stabilized zirconia were adopted in order to determine the oxygen partial pressures in an atmosphere of a CO₂–H₂ mixture.
A nonstoichiometric spinel and metallic phases are observed in the oxygen partial pressures between 10^−11.46 and 10^−12.45 Pa at 1153 K. The spinel-type solid solution is converted into FeO phase at much lower oxygen pressures.

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The undercooling attainable by the rapid quenching of Al–CuAl₂, eutectic alloy melt under different cooling conditions has been investigated. A solidification model considering the kinetics of eutectic growth is also presented. The experimental results is discussed in comparison with the results of calculation based on the present solidification model.

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The rotating-water-atomization process developed by the authors was applied to production of rapidly solidified powder containing Si between 7.1% and 23.7%. The particle shape was not spherical but tear-drop-like. The size distribution and the mean particle diameter were independent of Si content. The structure of an as-atomized particle was composed of finely dispersed Al and/or Si primary crystals in the eutectic matrix, and primary Si was hardly observed for Si contents less than 16%Si. The number of primary Si increased with increasing Si content. The variation, with Si content, of the lattice parameter of as-atomized particles showed a minimm at 16.3%Si. Two exothermic reactions were observed at about 500 K and 650 K, respectively, by DSC thermal analysis. Heat generatd at about 500 K was maximum at 16.3%Si and it was consistent with the lattice parameter variation. Coarsening of Si crystals at 723 K was very fast at the initial stage of annealing, and afterwards it was proportional to t^1⁄3.

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Rapidly solidified Al–Si alloy powders containing Si from 7.1% to 23.7% produced by the Rotating-Water-Atomization Process were hot extruded, and the mechanical properties were examined. The results are summarized as follows:
(1) Rapidly solidified powder was easily extruded at 593 K and 673 K without blister, and its surface quality was smoother, especially for higher Si alloys, than that of the cast material similarly extruded.
(2) Si crystals were precipitated and grew during the hot extrusion, and their size depended on the extrusion temperature.
(3) The tensile strength and hardness were much higher than the cast and extruded material without much loss of elongation. Finely dispersed Si crystals were evidently very effective in improving the tensile strength of the extruded Al–Si powder alloy. The tensile strength of Al-23.7%Si extruded at 593 K was about 360 MPa and its elongation was about 5%. The strength increased with decreasing extrusion temperature.

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Effects of titanium addition to the niobium core on the composite-processed Nb₃Sn superconductor have been investigated. Composites consisting of a Nb-0,0.5,1,2,3,4 at%Ti alloy core and a Cu-7 at%Sn alloy matrix were fabricated into single-core and 16–core multifilamentary wires, and then heat treated to form Nb₃Sn layers. An enhanced formation rate of Nb₃Sn layer with increasing titanium content has been observed, while the Nb₃Sn grain size slightly increases with the titanium addition. The titanium addition of 1–2 at% to the niobium core produces a small increase in T_c, and further titanium addition decreases it. The addition of titanium to the core increases H_c2 by 4 T in accordance with the increase in the normal state resistivity. H_c2 of about 25 T has been obtained at 4.2 K by the titanium addition. J_c’s of Nb₃Sn at high fields (H>13 T) are remarkably increased by the titanium addition, which is mainly attributed to the enhancement in H_c2. J_c of 1.1×10⁹ A/m² and overall J_c of 2.0×10⁸ A/m² have been obtained at 4.2 K and 16 T for a single core wire and a 160-core multifilamentary wire, respectively. The Nb–Ti/Cu–Sn composite wire seems to be quite promising for applications in high magnetic fields ranging from 12 to 16 T.

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The characteristics of Ag–Al₂O₃ films electrodeposited from silver thiocyanate solutions containing Al₂O₃ particles were investigated. The following results were obtained. As the amount of added Al₂O₃ particles was increased, the amount of Al₂O₃ codeposition in the Ag electrodeposited film increased, with a subsequent increase in the wear resistance of the electrodeposited film. The Al₂O₃ particles codeposited in the films suppressed recrystallization of the Ag film. Dislocations in the annealed films moved in accordance with Orowan’s theory in the region where the effect of concentration of Al₂O₃ particles on the yield stress of the film can be disregarded. As more Al₂O₃ particles codeposited in the films, the tensile stress of the films became lower. This was proposed as due to the compressive stress occurring at the interface between the Ag crystals and the Al₂O₃ particles. The electrical contact resistance of Ag–Al₂O₃ electrodeposited film was higher than that of Ag electrodeposited films.

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