The aging characteristics of a magnesium-4wt% zinc alloy were studied over a temperature range of 0°∼200°C by means of electrical resistivity and hardness measurements, the X-ray Debye-Scherrer method and electron-microscopic observations.
From the kinematic point of view the aging sequences were analyzed using the C-curve obtained by plotting the logarithm of the incubation time as a function of the reciprocal of the absolute aging temperature. The results showed that the aging sequences varied with the three different temperature ranges, viz., above 110°, 110°∼60°C and below 60°C. The presence of the following three stages in the aging sequences above 110°C were also confirmed by X-ray analysis and electron microscopic observations; supersaturated solid solution→pre-β′→β′→β(MgZn). The apparent activation energy calculated from the slope of the linear part of the C-curve was about 29 kcal/mol for β′ precipitates and about 24 kcal/mol for pre-β′ precipitates. The aging sequences in the temperature ranges of 110°∼60°C and below 60°C may be characterized by the formation of G. P. zones.

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Hardness measurements and electron microscopic observations were made to study factors affecting the aging of Mg–Zn alloy and Mg–Zn–(Ag) alloys. In regard to the homogeneous and heterogeneous nucleation in these alloys, direct aging, two-step aging and strain aging were carried out, with the results summarized as follows:
(1) The aging sequences are distinguished by the intersection temperature in the C-curve diagram. Below about 100°C, the nucleation rate largely depends on the quenching rate, the concentration of zinc and the small amount of silver (0.04wt%).
(2) In the C-curves which were obtained by plotting the incubation time against the reciprocal of the absolute aging temperature, the nose or the lower part of it gives an optimum condition for the pre-aging. As regards the direct aging and the two-step aging, silver atoms positively act on the nucleation of the pre-β′ or the β′ phase.
(3) The rates of precipitation of the β′ and β phases are accelerated by cold working before aging. Electron microscopic observations show that these phases preferentially precipitate on dislocations and fine structures such as twin boundary and sub-boundary.

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Magnetic properties of Ag–Mn–Sb alloys containing 2.49∼69.95% Mn and 4.58∼70.02% Sb have been measured. It has been found that the alloys consisting of about 13∼34% Mn, 23∼42% Sb and 26∼64% Ag show high coercive forces when tempered at 50°∼200°C after chill casting, and also that the alloy consisting of 24.08% Mn, 35.10% Sb and the balance Ag exhibits the highest coercive force of 1600 Oe and a residual intensity of magnetization of 27 e. m. u. Further, it has been determined by means of electron microscopic observation and X-ray analysis that these alloys of high coercivity consist of many fine particles of the ferrimagnetic compound Mn₂Sb which are dispersed in the matrix of the nonmagnetic α_Ag phase. The high coercivity of these alloys is probably caused by the crystal- and shape-magnetic anisotropy energies in those fine particles of a single magnetic domain.

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Thermal expansion within a temperature range of −150°∼900°C and Young’s modulus within a temperature range of −150°∼700°C and the rigidity modulus at room temperature of Fe–Cr alloys containing 0∼59.10% chromium have been measured. It has been found that the mean linear coefficient of thermal expansion at 0°∼40°C show minimum values of 9.94×10⁻⁶ and 10.60×10⁻⁶ in the annealed alloys containing 19.90% and 54.10% chromium, respectively, thereby revealing the Invar property. Fe–Cr alloys with a concentration range of about 17∼39% chromium exhibit the Elinvar property, the highest transition temperature being 230°C in an alloy containing nearly 25% chromium. The negative minimum value of the temperature coefficient of Young’s modulus at 0°∼40°C is −6.81×10⁻⁵ in an alloy containing 19.43% chromium. The Elinvar property is also observed in the Fe-54.10% Cr alloy with a negative minimum value of −9.60×10⁻⁵ at 0°∼40°C.

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Rod-form single crystals of Fe-19.43% Cr alloy of the bcc type about 3 mm in diameter and 12 cm in length were prepared. The thermal expansion and Young’s modulus in the temperature range −150°C to 250°C and the rigidity modulus at 20°C of the alloy were measured by means of a dilatometer, a vibrator-controlled oscillator system and the torsion pendulum method, respectively. The results of calculations based on the measured values have shown that the Young’s moduli of the single crystals at 20°C in the ⟨100⟩, ⟨110⟩ and ⟨111⟩ directions are 14.22×10⁵, 22.23×10⁵ and 27.37×10⁵ kg/cm², and the rigidity moduli at 20°C are 11.36×10⁵, 7.21×10⁵ and 6.43×10⁵ kg/cm², respectively ; the elastic anisotropy is not very large in all cases. The Young’s modulus in the ⟨111⟩ shows a small minimum at 10°C and a small maximum at about 110°C with increasing temperature, while the Young’s moduli in the ⟨100⟩ and ⟨110⟩ directions monotonously decrease. The mean temperature coefficients of Young’s modulus at 10°∼110°C are −32.77×10⁻⁵, −9.85×10⁻⁵ and +4.71×10⁻⁵ in the ⟨100⟩, ⟨110⟩ and ⟨111⟩ directions, respectively. The calculated value of Young’s modulus for the polycrystal agrees fairly well with the measured value for the polycrystal specimen prepared by melting.

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Since the original discovery by Masumoto et al. of “Nimalloy” in the Ni–Mn system which exhibits high permeability in a properly ordered state, much work has been done so as to investigate the effects of additions of various elements on the characteristics of Nimalloy. For developing excellent magnetic properties, the cooling rate should be as rapid as possible for Ni–Mn–Fe alloys and as slow as possible for Ni–Mn–Cr alloys. Therefore, an investigation has been carried out on the magnetic properties of Ni–Mn–Fe–Cr alloys in order to obtain the alloys which exhibit high permeability at a moderate cooling rate. As a result, the highest initial permeability of 53950 has been obtained with the alloy composed of 78.59% Ni, 14.01% Mn, 4.05% Fe and 3.35% Cr when cooled from 900°C at a rate of 240°C/hr, and the highest maximum permeability of 231000 with the alloy of 78.64% Ni, 14.46% Mn, 4.02% Fe and 2.88% Cr when cooled from 900°C at 100°C/hr. The latter alloy shows a coercive force of 0.0043 Oe and a hysteresis loss of 11.42 erg/cm³/cycle for a maximum magnetic induction of 2000 G, and its electrical resistivity being 75.0 μΩcm.

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The effect of Ag on the precipitation processes in Al–Mg–Si alloys has been investigated by the specific heat measurement.
In the specific heat versus temperature curve of the quenched Al-1.0wt% Mg₂Si alloy, the heat evolutions due to the formation of the ordered G. P. zones (β″) and the intermediate phase β′, the heat evolution due to the transformation β′- the stable phase β and the heat absorption due to the dissolution of β into the matrix were found respectively. The addition of 0.1wt% Ag increased the temperature for the dissolution of β into the matrix, suggesting that the degree of the supersaturation of solute atoms in the matrix is increased. It was also shown that the specific heat curves of specimens with Ag aged at 100° and 200°C immediately after quenching and after pre-aging at room temperature were different from those without Ag. A large shift of the peak temperature of the heat evolution due to the transformation β′–β occurred in the specific heat curves of specimens with Ag pre-aged at room temperature and aged at 100°C after pre-aging. The activation energies of the heat evolutions due to the formation β″ and β′ in the quenched specimens with and without Ag were determined to be 0.92 eV, 1.40 eV, 1.65 eV and 1.70 eV, respectively. From the above considerations, it is concluded that the addition of Ag accelerates the rate of the formation of β″ and stabilizes them.
Pre-aging at room temperature for 75 hr delayed the rate of the formation of β′ from the matrix following by aging at 100°C for 30 min and at 200°C for 45 min.

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High-purity aluminium bicrystals which have grain boundaries making an angle of 45° with the tensile axis were prepared by the recrystallization method. During the creep and the constant-rate heating tests under constant tensile load in argon atmosphere at high temperatures, the grain boundary sliding and the shear deformation were observed near the boundary. The grain boundary sliding increased stepwise against the time in the tensile creep test. The grain boundary sliding was accompanied by the shear deformation of the crystals near the boundary, and the grain boundary displacement had no relation with the boundary misorientation angle θ, but depended upon the angles, α_A or α_B, between the slip traces and the boundary trace on the observed surface. The contribution of grain boundary sliding to the total deformation of the specimen became larger with the increase of the testing time at 300° and 350°C, and showed the maximum value of about 36% at 400°C for 300 min. Grain boundary migration took place in the direction to release the strain energy of plastic deformation that occurred locally at the boundary irregulalities. The initial grain boundary displacement was proportional to the heating temperature, and the obtained activation energy for the boundary sliding of the specimens with α_A+α_B\simeq18°∼71° was 11600∼26400 cal/mol.

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Polycrystalline copper and silver films, about 2 to 10 μ thick, were vacuum-deposited on glass substrates using tungsten baskets. The variations of 0.2% offset yield stresses and microstructures of the films by annealing at various temperatures ranging from 100° to 1000°C were investigated. The grain size, which was about 2000 Å in diameter in an as-deposited state, increased to several microns in diameter after annealing. The grain size and recrystallization temperature were extremely affected by the deposition condition. The recrystallization temperature of copper films of 10⁻⁴ Torr rose above 800°C when the deposition was done in a high residual gas pressure. It is inferred that the fine dispersion of oxide in the films is responsible for the rise of the recrystallization temperature. The strength of the fine-grained films was agreed well with that expected from the Hall-Petch relation.

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The growth of the modulated structure during isothermal aging and the influence of the growth on the yield stress of aged Cu-5 at%Ti alloy was investigated. The wave lengths and amplitudes of the modulated structure were obtained from angular distances between the side band and the matrix reflections and from the ratio of reflection intensities of the side band to the main reflection, respectively. The results obtained are as follows: (1) In the early stages of aging, Cu-5 at% Ti alloys have a modulated structure, the wave length and the amplitude of which increase continuously with aging. (2) Experimental results of the yield stresses of the alloys in the early stages of aging seem to support Cahn’s theory based on an interaction between a dislocation and the sinusoidal internal stress fields due to the compositional modulation. In the later stages of the structural modulation, the yield stress is smaller than Cahn’s theoretical values. This disagreement is considered to be caused by the change of the structure from the sinusoidal to rectangular distributions.

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An infrared spectroscopic method was developed for a rapid identification of trace amounts of boron nitride (BN, less than 0.0001% of boron as BN in steel) in the residues extracted with sulphuric acid from steel samples. From the studies on commercial boron nitride (BN) and the residues which were found to contain boron nitride by elementary analysis and electron diffraction, boron nitride was newly found to have strong characteristic absorption bands at 819 and 1383 cm⁻¹ and to be readily identified by these bands without interference from compounds usually contained in the residues. A recommendable procedure is as follows : The residues by the acid extraction from 2∼5 g of the chipped sample is collected through the Millipore filter (100 mμ) and dried at room temperature. The residue is transfered into 300 mg of potassium bromide powder with Johnson’s method and ground well in an agate mortar with potassium bromide for about 20 min. Infrared spectrum is measured over the frequency region between 600 and 1600 cm⁻¹, using the disk-like pressed powder (13 mm in diameter and 1 mm in thickness). Boron nitride is identified by the characteristic bands at 819 and 1383 cm⁻¹. This method may be developed for a quantitative analysis of trace amounts of boron nitride in the residues extracted from steel.

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In order to get more information about the Zener relaxation than ever reported and, furthermore, to elucidate the interrelation between the relaxation effect and diffusion phenomena, the Zener peak which appears around 500°C has been investigated in the range of 11.1 to 30.0 at% Al by means of the internal friction technique. The activation energy, H, and the term D₀ of the diffusion coefficient deduced from the relaxation time are roughly given by
H=73.4−71.8c(kcal/mol),
and lnD₀=5.35×10⁻⁴H−27.8(cm²⁄sec)
where c is the atomic fraction of Al, respectively. Referring to the result of inter-diffusion, it has been argued that the diffusion of Al atom is possibly responsible for the relaxation effect in Fe–Al system. A definite correspondence has been found to exist between the changes of the half-width and of the relaxation strength of the Zener peak against Al concentration.

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