The grain boundary relaxation of Al–Fe alloys was studied by internal friction measurement. The relaxation strength of the grain boundary peak increased significantly as grains grow from equiaxial to bamboo-type grains by annealing at high tempetatures. The peak of the bamboo structure (BP) resembles in some respects with the HTP observed in the previous work, though its peak temperature and activation energy are much lower than those of the HTP reported on pure aluminium. This peak is suppressed significantly when a small amount of iron precipitates in the grain boundaries. All of the features of the BP may be accounted for on the basis of the mechanism of grain boundary sliding.

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Heat-treatment in sulfur atmosphere can control the defect concentration in crystals in the Ni–S system. In the composition range of Ni_1−xS, two different phases have been demonstrated, one of which takes a disordered structure and the other an ordered structure.
The disordered phase has been found to have the NiAs-type structure with a partial ordering of vacancies. X-ray diffraction patterns of the ordered phase contain superlattice reflections corresponding to the hexagonal cell with dimensions a′=3a₀ and c′=3c₀ and streaks along the c^* axis. Two superstructures belonging respectively to space groups P3₁21 and P3₂21, have been proposed, where vacancies are ordered corresponding to the composition Ni₁₇S₁₈. Electron diffraction investigation indicates that the domain size of each superstructure is larger than about 0.5 μm.
Electric resistivity and magnetic susceptibility at the metal-semiconductor transition for the disordered phase showed hysteresis with tempetature cycling. The transition occurs only in the disordered Ni_1−xS phase, while in the ordered phase all the samples remain metallic at temperatures down to 4.2 K.

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High resolution electron microscopy and selected area electron diffraction have been applied to investigate an unstable ordered phase formed in iron-carbon martensite tempered around 70°C. This phase can be identified with Izotov-Utevskiy’s Fe₄C, but different from their observation of superstructure spots, the present observation has revealed that they are splitted in two along the [001]_α′ direction in the reciprocal lattice of martensite α′. Electron diffraction structure analysis shows that the ordered phase takes an orthorhombic lattice with parameters a=b=√2a₀ and c=12c₀ (a₀ and c₀ are the lattice parameters of martensite), in which interstital carbon atoms or vacancies make a long period of ordered arrangement. The space group is Pmna. It has also been shown that the carbon content of this phase is not much different from that of matrix martensite. The ordered phase takes a needle-like shape with a size of about (1.5)²×10 nm³ and are randomly distributed in the matrix. The crystal structure and the related diffraction phenomena are discussed.

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The distribution of Cu, Ni, Co and Mn between an aqueous solution of constant ionic strength and Versatic Acid 911 diluted with benzene was investigated. Only one extracted species of Cu was revealed to have a dimeric structure of the composition (CuR₂·RH)₂, while both monomer and dimer were found in the extraction of Ni, Co and Mn. The curve-fitting method was employed to determine these species, from which the composition of the extracted species was found to be NiR₂·4RH and (NiR₂·2RH)₂, CoR₂·4RH and (CoR₂·2RH)₂, and MnR₂·4RH and (MnR₂·2RH)₂, respectively. The apparent equilibrium constants of the above species and those between monomer and dimer were also determined. The curve-fitting method was proved to be a precise method for determining the equilibrium constants and extracted species.

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The surfaces of 65/35 brasses with normal and reddish color have been studied by XPS, EPMA and X-ray diffraction. Both brasses are coverd by very thin surface films (2–3 nm thick) and reveal normal zinc contents at a depth of more than 10 μm. However, the surface region of less than 1 μm is fairly dezincified. The dezincification is most serious in the surface within a depth of 10 nm under the surface film, particularly in the reddened sample. The skin depth of light with a wavelength of 1 μm is about 4 nm for pure metallic copper and the thickness of the surface film is too small to cause the coloration. It was concluded, therefore, that the cause of the reddening is due to the enrichment of copper at the underlying alloy surface by the dezincification.

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The Bauschinger effect was measured by tension-compression tests for single crystals of Al-1.2%Si and Al-0.6% Si alloys containing silicon particles to estimate the contribution of mean internal stress due to Orowan loops to the work-hardening.
The crystals aged to contain silicon particles showed a pronounced Bauschinger effect. The reverse flow curves (compression) after tension showed in general an initial region of rapid work-hardening, subsequently a region of nearly linear and low work-hardening and finally a region of a parabolic work-hardening, as seen in Cu–Al₂O₃ alloy. However, when the crystals with small particles (2R\lesssim30 nm) were deformed by a small amount of strain in pre-straining, the reverse stress-strain curve showed a sharp convex curvature in the region of rapid work-hardening, which was associated with the inhomogeneous deformation in pre-straining by a small amount of strain.
The mean internal stress estimated from the Bauschinger effect increased initially with pre-strain, in reasonable agreement with the theoretical mean internal stress due to Orowan loops until a critical strain, ε_c, and then appeared to saturate with increasing pre-strain. This explained the most part of work-hardening in a region of strains below a critical strain, ε_s. With increasing pre-strain above the ε_s, the contribution of forest hardening became progressively important.
The ε_c and ε_s, which were considered a measure of critical strain for the plastic relaxation and for the forest hardening respectively, increased with decreasing mean particle size. In a range of large particle size (2R\gtrsim30 nm), ε_c=3b⁄R (b: Burgers vector, R: mean particle radius). As the particle radius became smaller than 30 nm, the ε_c, appeared to approach a limit of about 0.06. Such particle size dependence of the ε_c was discussed in terms of the plastic relaxation due to the secondary dislocation generation as well as due to cross-slip of Orowan loops.

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