The effect of three different rolling temperatures on dynamic recovery and recrystallization in an iron-containing copper-aluminium alloy has been evaluated. Rolling at about 980°C in the β phase field results in dynamic recrystallization and fine-grained material is obtained. Iron particles precipitated during rolling inhibit grain growth. By rolling the material at 800 and 650°C, where the structure consists of (α+β) phases, elongated fibrous crystals are obtained. The dynamic recovery at these temperatures is so remarkable that subsequent high temperature annealing does not induce any recrystallization, but annealing for longer periods of time results first in some ‘perfection’ of the sub-structure and later also of the grains, and the fibrous structure disappears.

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The arc on breaking of silver, tungsten and carbon contacts has been observed by means of an oscilloscope in the range of applied voltages from 20 to 110 volts and of testing currents from 0.3 to 50 amperes at both d.c. and a.c. noninductive circuits. Through the observations, length L, voltage e and current i of the arc are given by the following equations:
(Remark: Graphics omitted.)
where E is the applied voltage, I is the testing current, E_m is the minimum arc voltage, I_m is the minimum arc current, υ is the breaking speed, ω is the angular velocity, φ is the breaking phase angle, T is the arc duration, t is the time and K is a constant; in the case of d.c. circuit, the sin(ωt+φ) is equal to unity. These equations are applicable for the materials of both thermionic emission and field emission (T–F mechanism).

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X-ray diffuse scatterings at both small and high angles (111 Bragg angle) were measured with powder samples of Al-6.8 at%Zn base alloys containing 0.06 to 2.0 at%Mg.
In the alloys with low Mg concentrations the diffuse scattering around the 111 Bragg peak shows a size-effect scattering; the intensity becomes weaker with increasing Mg concentration and is scarecely observed beyond a certain Mg concentration. Such changes of scattering profiles with Mg concentration arise from the changes in static distortion around and inside a zone. The G.P. zones of the ternary alloys are discussed in view of this static distortion.

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The thermoelastic martensite transformation from the β₁ phase to the γ′ phase in Cu–Al–Ni alloy has been analyzed by the phenomenological theory, special attention being given to the understanding of the unique morphology. It is shown that there are a pretty good agreement between the theory and experiment with respect to the habit plane and the orientation relationship and a less good agreement with respect to the relative twin width, for δ=1. The unique “spear-like” morphology of the martensite was found to be consistent with the theory when it is applied in the two variants independently with a different lattice correspondence, and the morphology is fully explained from crystallographic aspects. Finally, the reason why the martensites take the spear-like form in the present alloy is explained as a result of the self-accommodation effect so as to minimize the strain energy set up by the formation of martensites, by using the result of the phenomenological calculations.

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The {121}_γ′ and {101}_γ′ twinnings in γ′ Cu–Al–Ni martensite with Cu₃Ti type ordered structure, whose sublattice is HCP, have been analyzed by the theory of deformation twinning and the phenomenological theory of martensitic transformations. As a result the following conclusions have been reached:
(1) The twinning elements of {121}_γ′ twinning consistent with the phenomenological theory are as follows. K₁=(\bar1\bar21)_γ′, η₁=[1,‾0.7954,‾0.5907]_γ′, K₂=(1,‾1.5036,‾0.5036)_γ′, η₂=[\bar1\bar11]_γ′, s=0.261.
(2) In spite of the ordered structure, the original structure can be restored by the above twinning mode and simple and small shuffles, thus providing a theoretical background for experimental evidences such as the mobile nature of twin boundaries and the absence of extra spots in electron diffraction patterns.
(3) {101}_γ′ twins are considered to be variants of martensite rather than a lattice invariant strain in a variant of martensite.
(4) In spite of (3), {101}_γ′ twinning can be treated by the theory of deformation twinning, and no structural change is introduced by the twinning with the required twinning shear and simple and small shuffles. This is consistent with the experimental findings.
(5) No distinction can be made between the mechanism of deformation twinning and that of transformation twinning in the present martensite, although the structure is ordered.
(6) It is suggested that the absence of {10\bar12} twinning as a lattice invariant shear in most hexagonal martensites is due to the fact that no solutions of the phenomenological theory exist for δ nearly equal to unity.

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The coarsening of lamellar eutectic alloys is controlled by faults in the as-grown structure. A model, based on the use of In cosh cylinder co-ordinates, is proposed to calculate the rate of shrinkage of lamellar terminations. It is found that for high volume fractions and diffusion through the continuous phase around the fault, the fault shape remains approximately constant and a value can be obtained for the rate of shrinkage of an isolated fault. For the case of interface diffusion, the shape is not preserved and only the initial shape changes can be calculated. The problem of coarsening of an array of faulted lamellae is considered. The important variables in the coarsening rate are the lamellar spacing and fault density. These results are compared to the experimental observations of Graham and Kraft on unidirectionally solidified Al–CuAl₂ alloys.

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In the presence of oxygen more than an atmospheric pressure, laterite ore containing nickel which is previously reduced dissolves in a NH₃–(NH₄)₂SO₄ solution by the following reaction: Ni·Fe+O₂+(n+m−4)NH₃+4NH₄⁺→Ni(NH₃)_n²⁺+Fe(NH₃)_m²⁺+2H₂O where n and m are the integral numbers between 1 and 6, respectively. In the current investigation, the kinetics of this reaction has been examined by changing the concentrations of NH₃ and NH₄⁺ ion, partial pressure of oxygen, stirring velocity, temperature, and surface area. The leaching reaction of laterite ore in a solution containing both ammonia and ammonium sulfate is shown to be the zero-th order, because of the linearity found in the leaching time curve. The leaching reaction is accelerated by increasing temperature and stirring the leaching solution. The apparent activation energy calculated from the Arrhenius plots is 4690 cal/mol. The leaching rate is also proportional to the surface area and the partial pressure of oxygen. Therefore, the transport process of the dissolved oxygen in the leaching solution is assumed to be the rate-determining step of the leaching reaction and the chemical process may be much faster than the diffusion rate of oxygen. In addition, the leaching reaction of laterite ore is well explained by an electrochemical mechanism, and the cathodic reaction of oxygen is found to be the rate-determining step of the leaching reaction.
According to the experimental results obtained, the leaching rate equation for laterite ore containing nickel in a NH₃–(NH₄)₂SO₄ solution under the presence of pressurized oxygen is as follows:
Leachingrate=K·S·Po₂·V(x)·e^−4690⁄RT
where K is the rate constant, S the surface area of the laterite ore reduced, Po₂ the partial pressure of oxygen, kg/cm², V(x) the stirring velocity, rev/min (x is unknown because the sample is in the pulverized state), R the gas constant, and T the absolute temperature.

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Crystal structure and precipitation mode of the carbide in a martensitic 0.45 wt%C steel tempered at 120 and 200°C have been studied by means of electron microscopy and selected area diffraction. In both plate-like and lath martensites, the precipitated carbide is η-Fe₂C like the previous case of high carbon steel (Acta Met., 20 (1972), 645). The crystal morphology and the orientation relationships between the carbide and the matrix are also the same. In general, the precipitation occurs along dislocations, but it has been found that grain boundary precipitation also takes place in the non-parallel lath region and that in fine grains in this region the carbide precipitation does not occur. Some discussions are given to the crystal structure and the precipitation mode of the carbide.

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Crystal structures and magnetic properties of Pd–Mn–Te alloys have been investigated by means of X-ray diffraction and magnetic balance, respectively. It has been found that the alloys of near-stoichiometric compositions are of Cl_b type structure and form a solid solution having lattice parameters of about 6.269∼6.274 Å at room temperature in the composition range of Pd_1.0125Mn_0.975Te_1.0125∼Pd_0.975Mn_1.05Te_0.975. The compound PdMnTe was assumed to be antiferromagnetic from the temperature dependence of magnetic susceptibility, the Néel temperature being 22°K. The paramagnetic Curie temperature and the effective Bohr magneton number per Mn atom were evaluated to be 25±3°K and 5.28, respectively.

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The strain gauge factor K at room temperature, the electrical resistivity ρ at 20°C, the mean temperature coefficient of electrical resistivity C_f at 0∼40°C and the mean thermoelectromotive force relative to copper E_mf at 0∼40°C have been measured for wire specimens which had been prepared from Fe–Co–Mn alloys of high workability containing 20∼50%Mn and less than 80%Fe by a cold work of about 94% reduction. The value of K attains the highest value of 5.4 in an Fe–Mn binary alloy containing 30%Mn and decreases gradually with the addition of Co, but the value becomes higher than 4 in the nonmagnetic γ phase region. The value of ρ for Co–Fe alloys increases with increasing Mn content, while the E_mf shifts from a negative to a positive value. The value of C_f is high in Fe–Mn and Fe–Co alloys but decreases with the respective addition of Co and Mn. In an Fe-30%Co-45%Mn alloy which shows the lowest C_f value of 2.4×10⁻⁴, the values of K, ρ and E_mf are 4.6, 98 μΩ-cm and +0.2 μV/°C, respectively. The variations of these values by heat treatment below 500°C for 150 hr have also been measured.

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The kinetics of ordering in Fe–Al alloys with about 25 at%Al is investigated both theoretically and experimentally. The kinetic equations which express the time variation of the degrees of order in B2 and DO₃ structures are obtained by taking into account the direct interchange of atoms between the first and the second nearest neighbors. The experimental results of X-ray diffraction for these alloys on isothermal annealing or slow cooling are reproduced satisfactorily by theoretical rate equations, and the characteristics of the ordering in the Fe–Al system is investigated. The ordering in DO₃ type is influenced substantially by the atomic interchange between the second nearest neighbors. The B2 type ordering takes place so rapidly that the quenching from a disordered phase does not prevent the ordering. An oscillatory change of the degree of order in the B2 structure is expected from the calculation in the isothermal annealing.

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In order to clarify the cause of quench-hardening in Ni-rich NiTi, the relation between composition and electrical resistivity, and the change in the electrical resistivity at a constant rate of heating for NiTi have been measured.
On the Ni-rich side of the stoichiometry, the electrical resistivity increases with increasing nickel content for water-quenched specimens and remains constant at non-stoichiometric composition for slowly cooled specimens. The measurements of electrical resistivity at a constant rate of heating for water-quenched Ni-rich NiTi show a significant decrease in the electrical resistivity around 300 and 700°C. Above 700°C the electrical resistivity changes in the same manner as slowly cooled specimens. Activation energies were 1.1 eV for the low temperature reaction and 3.7 eV for the high temperature reaction. The electrical resistivity for the specimens of stoichiometric composition and those containing 55 at%Ni after being ordered just below the critical temperature increases with increasing temperature. No significant change in the electrical resistivity due to the order-disorder transformation or the eutectoid reaction was observed.
The analysis of the results of the electrical resistivity measurement indicates that the ordered NiTi phase is stable but has a restricted homogeneity range at low temperatures, the precipitation of Ni₃Ti in the water-quenched state is hardly conceivable and the existence of the order-disorder transformation and the eutectoid reaction is improbable. Therefore, it can be concluded that the quench-hardening in non-stoichiometric NiTi is due to the existence of structure defects.

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