A kinematically admissible velocity field was proposed to describe the flow in axisymmetric indirect extrusion. The deformation zone is bounded by two spherical surfaces of velocity discontinuities, having radius R₁ and R₂ with their centers at a.R₁ and a.R₂ from the apex of a conical die. The coefficient a varies depending on the process variables including the friction factor. The flow in the deformation zone is directed along radial lines toward the apex of the cone. An upper bound approach was applied in order to obtain information about the deformation process, and the analytical results were compared with various experimental data. There was good agreement between the experimental and analytical results in relation to the flow characteristics. From the present work, it was suggested that, for extrusion through large angle dies, redundant shear in the outer surface of the indirectly extruded bar exceeds that of the directly extruded one.

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Magnetic properties, electrical resistivity, hardness and microstructure have been studied on Fe–Nb alloys “Recalloy” containing less than 4%Nb. The alloys are water-quenched from various temperatures over the α-γ transformation point, cold-drawn by more than 50% reduction, and then reheated at 400–1000°C for less than 5 h.
The magnetic properties of these alloys depend remarkably on the reduction rate, reheating temperature and time. An Fe-3.1%Nb alloy reheated at 650°C for 30 min after water-quenching from 1050°C and subsequent cold-drawing by 97.2% reduction exhibits very superior properties as follows: magnetic induction at 8 kA/m B₈=1.74 T, residual induction B_r=1.62 T, coercive force H_c=1.62 kA/m, squareness ratio B_r⁄B₈=0.93 and squareness \sqrt(BH)_max⁄B_rH_c=0.90. The electrical resistivity and Vickers hardness of this alloy are 0.126 μΩm and 353, respectively.

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The general structure of the kinetic equation describing the short range ordering in binary substitutional alloys is discussed, by assuming that the ordering takes place by the migration of vacancies, which are created or annihilated at dislocations and grain boundaries. The basic equation is applied for an analysis of the observed variation in electrical resistivity of αCu–Al in the course of annealing at the same temperature, after the specimen is quenched from various temperatures.It is shown that by a suitable choice of the value for vacancy formation energy those data fit on a single master curve, if an appropriate transformation of the time scale is performed. The basic equation is not strictly linear, but can be linearized under certain limited circumstances. The approximate rate equation can account for the change of resistivity, specific heat and lattice constant of αCu–Al under various heat treatments.

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Compressive and tensile tests were performed using both single and polycrystal specimens of an intermetallic compound Ni₃Al which is usually believed to be brittle, and especially the ductility was examined by comparing the elongation of specimens with fracture surface observations. Main results obtained are summarized as follows.
(1) Polycrystalline specimens homogenized after casting do not show any elongation by tension at every temperature, and the fracture surfaces exhibit an intergranular fracture mode. On the other hand, compressive plastic deformation is possible to some extent, though intergranular fracture is also accompanied.
(2) Single crystal specimens show about 100% elongation at and below room temperature. At higher temperatures, the elongations markedly decrease with increasing temperature and attain minimum values at the peak temperature of yield stress. Fracture modes are all ductile ones, showing a dimple pattern observable at a large magnification.
(3) Polycrystal specimens, which were obtained by recrystallization annealing of the cold rolled single crystals, show about 15% elongation even at room temperature. Fractography shows transgranular as well as intergranular fracture. Thus, the lack of ductility in Ni₃Al polycrystals seems to be caused mainly by segregation of impurity atoms to the grain boundary.

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Kinetic behavior of the 550°C-change in ordered FeCo alloy has been investigated by the measurement of specific heat C_P and temperature derivative of electrical resistivity α_R. Since α_R has been found to be nearly proportional to C_P in FeCo, just as in βCuZn alloy, α_R has been compared with the corresponding theoretical value calculated with the kinetic equation of ordering which was derived in our previous papers on the basis of the Bragg-Williams approximation. The measured value for α_R and the calculated one as a function of temperature are in good agreement with each other in regard to the shape of the curves and the dependence of the temperature of the change on the rate of increasing temperature. This fact shows the validity of the kinetic interpretation of the 550°C-change.

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Heat-treatment in selenium atmospheres was used to control defect concentration in the Co–Se system. In the composition range of hitherto reported γ-CoSe, three different regions were demonstrated in discontinuous vapor pressure-composition relationships. Each region may be expressed in the following representative compositions: (CoSe_1.03), (CoSe_1.13) and (CoSe_1.30). A solid solution range was not detected in any of the three regions within the limit of error of chemical analysis.The stable region of each phase is shown in the P-T phase diagram.
X-ray and electron diffraction patterns were obtained for single crystals grown by the Bridgman method or by chemical transport reaction. The (CoSe_1.03) phase has the NiAs type structure. The (CoSe_1.13) phase is consistent with a superlattice of the 3c-type Fe₇Se₈ structure, which is closely related to the NiAs structure by ordering of metal vacancies. The magnitude of splitting and the intensities of superlattice reflections change depending upon the controlled selenium pressure. (CoSe_1.30) is a monoclinic phase of the 2c-type Fe₃Se₄ structure, which can be regarded as a slight distortion of the NiAs structure. The precession X-ray patterns were explained in terms of multiple twinning around an axis perpendicular to the basal plane.
All specimens in these three phases show metallic conductivity, the order of 10⁴ mho/cm at room temperature. The magnetic susceptibility is weakly paramagnetic and nearly independent of temperature.

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