Attention is directed to the uncertain state-of-affairs surrounding the influence of plastic deformation on concommitant tracer-diffusivity in metals. We now offer some clarification of this elusive solid-state transport problem.
It is concluded that strain-enhanced diffusion is a real phenomenon, and in fact, it can be of substantial magnitude if the strain-rate is high enough and/or the temperature low enough. However, the dynamic-diffusivity measurements can be obscured by spurious mass movements in the diffusion zone arising from inadvertent specimen roughening or nonuniform bulk flow. The diffusivity enhancement per se occurs during compressive or tensile plastic deformation in poly- or mono-crystals, and in face-centered or body-centered cubic metals.
Arguments are presented against the vacancy model as an explanation of the observed deformation/diffusion effects; instead, the dynamic diffusivity is accounted for by the presence of moving dislocation which provide high-diffusivity paths for the tracer atoms. The concentration profile remains Gaussian, indicating that the overall process is essentially one of random-walk under the prevailing conditions. Then, the temperature-dependence of the strain-enhanced diffusivity simply becomes the activation enthalpy for normal lattice diffusion minus that for dislocation-pipe diffusion. This interpretation can be checked by independent diffusion measurements under static conditions.
The “window” on the experimental determinations of strain-enhanced diffusivities is limited by (a) the requirement for a steady-state structure during the deformation/diffusion run, in order to achieve a constant dynamic diffusivity, (b) the selection of strain-rate/temperature combinations which will permit the dynamic diffusivity to be significantly larger than the static diffusivity, and (c) the avoidance of recrystallization which serves to eliminate the operative dislocation substructure.

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Transmission electron microscope observation has been made on the martensite of Fe-10.3% Al-1.50% C steel, with the following results: (1) the martensite gives the diffraction pattern of a body-centred tetragonal lattice with extra spots. These spots are coincident in position with those of the superlattice produced by the Bain distortion from the parent lattice which was assumed to be of the Cu₃Au type; (2) it has fine twin faults and stacking faults of the {112} type and not of the {121} type; and (3) the martensite crystals are generally wedge-shaped but some of them have a lamellar structure which consists of two variants having the c-axes approximately perpendicular to each other.

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Activation energies for high temperature creep determined under constant normalized stress, σ_c⁄E_T, agreed with activation energies for self-diffusion both in paramagnetic and ferromagnetic temperature regions of alpha iron. Activation volumes for creep deformation determined by stress relaxation tests during creep ranged from 5×10² b³ to 1.4×10³ b³. An analysis of the obtained results suggests that creep deformation of alpha iron is determined by the diffusion-controlled motion of screw dislocations which contain super-jogs. The height of the jogs was estimated at about 10b to 20b under different creep conditions. The super-jogs are supposed to be formed by the accumulation of elementary jogs produced on dislocations when the dislocations are pulled out from sub-boundaries. The dislocation densities and their stress dependence obtained on the basis of the motion of super-jogs were in good agreement with the results reported so far.

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Since the discovery of new high permeability alloys “Nimalloy”, the present authors have investigated the effects of additions of other elements on its properties. From a series of experiments, the highest initial permeability of 76000 and the highest maximum permeability of 441000 have been obtained. In Ni–Mn alloys containing Mo, the cooling rate by which the highest permeability is obtained decreases gradually with increasing Mo content. Therefore, in nearly all cases the alloys have been baked at temperatures below the order-disorder transformation point for a prolonged time after slow cooling from 900°C. With increasing Mo addition, both the initial permeability and the maximum permeability of Ni–Mn alloys increase gradually before reaching their peaks and then decrease monotonically. The composition of 77.67% Ni, 18.63% Mn and 3.70% Mo shows the highest initial permeability of 13720 when baked at 400°C for 340 hr after cooling from 900°C at 5°C/hr and the highest maximum permeability of 113400 when reheated at 400°C for 210 hr after cooling at the same slow rate. The coercive force and the magnetic hysteresis loss of the alloy are as small as 0.0240 Oe and 36.24 erg/cm³/cycle, respectively, for a maximum magnetic induction of 5000 G . The intrinsic magnetic induction and electrical resistivity are 8010 G (H=900 Oe) and 58.8 μ Ω-cm (20°C), respectively.

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Measurements of the thermal expansion, natural frequency of vibrations and magnetization in ferromagnetic cobalt-manganese alloys were carried out at various temperatures, and an equilibrium diagram was proposed. The equilibrium diagram shows that the ε-α transformation continues up to a composition range of 19.30% Mn and the magnetic transformation point in the α phase is 0°C at a composition of 28.20% Mn. Further, the thermal expansion coefficient and the temperature coefficient of Young’s modulus at room temperature were determined, from which it has been ascertained that a Co–23.85% Mn alloy in the ferromagnetic region of the α phase shows a minimum value of 14.04×10⁻⁶ in thermal expansion coefficient and a maximum value of 2.52×10⁻⁵ in temperature coefficient of Young’s modulus. The cause of such anomalous properties of the alloy can be explained by Masumoto’s rule in regard to Invar.

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Temperature dependences of thermal expansion and Young’s modulus in single crystals of 63% Fe-32% Ni-5% Co alloy were measured over a temperature range −30° to 600°C. The single crystal rods with several crystal directions were prepared to have a length of about 12 cm and a diameter of about 3 mm. The principal elastic parameters and Young’s moduli for the three principal directions calculated from the measured values of thermal expansion and Young’s modulus for the single crystals. The results showed that the temperature dependences of Young’s moduli for the three principal directions were similar to each other, and that the Young’s moduli at 20°C in the ⟨100⟩, ⟨110⟩ and ⟨111⟩ directions were 5.8×10⁵, 12.53×10⁵ and 20.42×10⁵ kg/cm², respectively.
The crystal anisotropy of Young’s modulus, E_⟨111⟩⁄E_⟨100⟩ of the alloy was estimated to be 3.52 at 20°C.

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The present study was made in an attempt to give a satisfactory answer to the question concerning abnormally large surface-activities in Pb–Sn alloys measured by the TIE method.
The surface- and the body-activities in the Pb–X systems, i.e. Pb–Sn, Pb–Bi, Pb–Sb, Pb–Ag, were measured simultaneously at 550°C by using a modified TIE method.
The difference between the two activities in the system Pb–Sn are remarkably large, while the others are not.
It was made clear that the measured surface- and the body-activities were reasonable compared with the body-activities calculated from the heats of mixing and also with the surface-activities measured by the usual e.m.f. methods.

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Precipitation of copper in iron alloy containing 1 wt% copper was measured from the changes in electrical resistivity at liquid nitrogen temperature and in tensile strength. In the specimens quenched from 800°C, rapid precipitation was observed at 525°C when subjected to isochronal aging, in which the temperature interval and the time were taken as 50°C and 30 min, respectively. The activation energy for the precipitation is determined as 53±6 kcal per mol. Meanwhile, in the specimens cold-worked after quenching from 800°C, copper was precipitated in a considerable amount at about 250°C under the same conditions of isochronal aging. The activation energy for the precipitation is calculated as 32±1 kcal per mol. Excess vacancies introduced into specimens by cold-working are considered to be effective in the diffusion mechanism for the precipitation at about 250°C.

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The activity-composition relationships for Fe–S melts have been established between 1100° and 1300°C using gaseous mixtures of H₂S–H₂. The activities of Fe(γ) and FeS(l), ΔG° for the formation of FeS(l), and the heat and entropy of solution were calculated from the experimental results.

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In order to study the solution rate of solid iron in the copper-iron system which exhibits a positive great departure from ideality, a cylindrical iron was rotated in liquid copper or liquid Cu–Fe alloys for 60 to 240 sec at 240 revolutions per minute at 1220°, 1310° and 1385°C. The results are:
(1) The dependence of the solution rate on the iron concentration cannot be explained by the conventional rate equations in which the driving force is given by the difference between the concentrations of iron at the saturation and in the bulk liquid. A rate equation which expresses the driving force by the difference between the activities of iron at the saturation and in the bulk liquid, can approximately explain the solution rates.
(2) The rate constant K_c defined by the Berthoud equation has a tendency to decrease with an increase in iron concentration, but the rate constant K_a defined by the new equation has no clear dependence on the iron concentration except the case of 3.4% Fe at 1385°C.
(3) There is no significant difference between the values of K_c at 1310° and 1385°C. A linear relationship is established between the logarithm of K_a and the reciprocal of absolute temperature, giving the activation energy of 42 kcal·mol⁻¹.

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An attempt has been made in order to investigate the effect of Cd atoms on the precipitation in Al–Cu alloys by means of a differential calorimeter.
A heat evolution was found over a temperature range between 190° and 280°C in the curve of power difference versus temperature of the quenched Al–Cu–Cd alloy and this heat evolution could be divided into two parts : the first of the two heat evolutions was attributed to the formation of the intermediate θ′ phase whose nucleation was stimulated by Cd atoms, and the second small heat evolution following the first one was due to the formation of the θ′ phase which was not related to Cd atoms.
The activation energies for the first and second heat evolutions were determined to be 0.6 eV and 1.7 eV respectively. The transformation θ′-θ in the quenched ternary alloy was delayed as compared with that in the quenched binary alloy. The effects of thermal histories of specimens, quenching temperature, Cd concentration and cold work were also examined.

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