The effect of the annealing twin boundary on plastic deformation of fcc metals was investigated by comparing the deformation behaviour of copper crystals containing a twin band with that of single crystals. As deformation proceeds, dislocations pile-up against the twin boundary and the slip mode near the boundary is changed from that in the centre of the grain. Therefore, the flow stress of a crystal containing a twin band is larger than that of a single crystal. The twin boundary acts as a barrier against the dislocation motion and the effect of the annealing twin boundary on plastic deformation of copper crystals is thought to resemble that of the grain boundary. Especially, it is pointed out that the annealing twin boundary must be treated in the same way as the grain boundary with respect to the Hall-Petch relationship.

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Polycrystalline specimens of Cu–30Ni–1Si alloy containing G. P. zones, semicoherent γ′ and the equilibrium γ phases have been subjected to a 2% plastic deformation in tension at ambient temperature. This was followed by a unidirectional compression. The observed Bauschinger effect has been analysed in terms of the current theories of precipitation hardening. The relative importance of the various contributions to precipitation hardening and the Bauschinger effect can be predicted on the basis of the present observation.
It is concluded that most of the Bauschinger effect in specimens containing G. P. zones can be accounted for by normal work-hardening in the matrix. The effect is found to increase with the coarsening of G. P. zones and reaches a maximum in the presence of semicoherent γ′ precipitate phase. This is due to an excessive pile-up of back stresses which assist in the reverse deformation. The Bauschinger effect decreases during the formation and coarsening of the equilibrium precipitate phase, γ, but the effect is still larger than those observed during the formation of G. P. zones in the very early stages of the precipitation process. The present observation matches very well with the data reported for an Al-4 wt%Cu alloy having a similar precipitation sequence. A mathematical equation has been developed to describe the variation of the total strain with the permanent softening.

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By employing the modified capillary-reservoir technique capable of measuring an electrotransport mobility, the differential mobilities in Sn–Bi molten alloys were determined over the entire composition range at three temperatures in the range of 400 to 600°C, in an attempt to correlate with the TIE study exploring ionic species. The significant modifications were the uses of both a salt cover on the molten alloy and a glass cover on the cell.
As a consequence, the differential mobilities in experiments with the salt cover differed markedly from them without it, and minimums of both such mobility difference and the mobility value, occurred at or near the composition of X_Bi=0.60 associated with an inflection point on the liquidus.
The mobilities thus determined and then the effective valences calculated theoretically were discussed in comparison with the reference values.

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The reversion phenomenon of Cu-3.17 wt% Ti alloy was investigated, with special attention to the reversion process of side band structure, by means of electrical resistivity measurements, X-ray diffraction, hardness and tensile tests, and transmission electron microscopy. The temperature ranges of aging and reversion were 300∼500°C and 350∼700°C, respectively.
Analysis of the electrical resistivity change shows the reversion process to be described by a first order rate equation. The activation energy for reversion was about 2.3 eV.
A reversion phenomenon is also observed in the mechanical properties and microstructure.
From the results of X-ray diffraction experiment, the reversion process of side band structure in this alloy is explained with a zone complex model with diffused periodicities.

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In order to establish the conditions for the preparation of pure vanadium trifluoride, VF₃, from ammonium hexafluorovanadate (III), (NH₄)₃VF₆, the preparation of (NH₄)₃VF₆ and its thermal decomposition have been studied by means of thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. Ammonium hexafluorovanadate can be prepared by heating a mixture of V₂O₃ and NH₄HF₂ in the molar ratio of 1:8–1:12 at 185–250°C in an inert atmosphere. Vanadium trifluoride can be prepared by heating (NH₄)₃VF₆ at 600–700°C in an inert atmosphere. The mechanism of thermal decomposition of (NH₄)₃VF₆ is as follows:
(NH₄)₃VF₆ → α → β → γ → VF₃,
in which α is believed to be ammonium pentafluorovanadate (III), (NH₄)₂VF₅, and β has been found to be a nonstoichiometric compound with the chemical formula of (NH₄F)_1−x·VF₃, 0≤x≤∼0.3, which belongs to a tetragonal system. The lattice parameters of ammonium tetrafluorovanadate (III), NH₄VF₄(NH₄F·VF₃), oare a=7.58, c=6.36, c⁄a=0.839. The composition of γ is very near to that of VF₃ and γ contains a small amount of NH₄F (about 0.1–1.5 wt% NH₄).

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The precipitation behavior in Fe–Mn–Cu austenitic alloys was studied by means of the hardness test, electric resistivity measurement, Mössbauer effect measurement, and optical and transmission electron microscopy. The main results obtained are as follows: In Fe–Mn–3Cu, Fe–Mn–5Cu and Fe–Mn–7Cu alloys, an age-hardening phenomenon was observed and the degree of hardening, became remarkable with increase in Cu content. In this alloy system, a two-phase decomposition was expected to occur and it was considered to be based on a miscibility gap in the Fe_0.5 Mn_0.5–Cu quasi-binary system. Namely, it was suggested that these Fe–Mn–Cu alloys were decomposed into a Fe–Mn rich (Cu-poor) phase and a Cu-rich phase. By means of splat-quenching from the liquid state an austenitic single phase of Fe–Mn–40Cu alloy was obtained and the two-phase decomposition was also expected to occur in this alloy.

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Crystal structures and magnetic properties of Rh–Mn–Sb alloys have been investigated by means of X-ray diffraction and magnetic measurements. It has been found that alloys in the composition range of Rh_1.00Mn_0.66Sb_0.34∼Rh_1.00Mn_0.55Sb_0.45 are a solid solution of the face-centered tetragonal L1₀-type with lattice parameters of 4.200∼4.182 Å and axial ratios of 0.806∼0.829. The typical Rh_1.00Mn_0.55Sb_0.45 alloy has a saturation magnetization of 52.3 emu/g at absolute zero, a magnetic moment of 3.20 μ_B per Mn atom, a Curie point of 330°K and a paramagnetic Curie point of 286°K. The observed relationship between reciprocal susceptibility and temperature indicates weak ferrimagnetic behavior of this alloy.

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Measurements of the properties of Ni–Fe–Nb–Cr alloys have been carried out after heating at 1150°C for 3hr in a hydrogen atmosphere and subsequent cooling at 0.75–300°C/hr from a temperature above the order-disorder transformation points. The results show that an alloy containing 79.80% Ni, 11.22% Fe, 8.03% Nb and 0.95% Cr exhibits the highest initial permeability of 105000 and the highest maximum permeability of 420000 when cooled at 30 and 50°C/hr, respectively. The alloy which has been cooled at 30°C/hr shows an electrical resistivity of 80.0 μΩ-cm and 199 Vickers hardness. The high permeability alloys in this quaternary system display very low magnetostriction constants.

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Copper-10 at% aluminum alloy single crystals with tensile axes in the [001], [112], [111], [212], [101], and [102] directions were extended in the temperature range between −195 and 800°C. Yield stresses resolved on the active slip systems were almost independent of crystal orientation below 400°C. Rotation of the tensile axis with deformation was observed by the slip line orientations appeared after an incremental deformation of specimens which were prestrained by various amounts at −195 and at 22°C. In [001], [111], and [112] crystals single slip is observed only in the easy glide region. In the [101] and [212] crystals the rotation direction of the tensile axis changed from the [011] to the [121] axis in the later stage of deformation. The maximum work-hardening rates on the load-elongation curves and the maximum true tensile stresses were compared with similar results obtained on pure copper single crystals (Trans. JIM, 16 (1975), 629); the former was about one-half of those of pure copper, and the latter was about twice larger than them.

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