Re-oxidation behaviour of a porous metallised iron pellet and morphologies of oxides formed at temperatures between 973 and 1173 K were studied. The increase in oxygen concentration resulted in not only an enhanced rate of re-oxidation but also a higher temperature rise in the pellet.
The re-oxidation proceeded usually with two stages; i.e. the initial stage of a high rate and the latter stage of a low rate. The physical nature of the oxide formed during the initial stage has a decisive influence upon the subsequent oxidation behaviour.
The oxide layers were associated with various deffects such as remaining pores, cracks and blisters. Furthermore, needle-like hematite crystals grew as a general occurrence for the re-oxidation of several metallised iron pellets. The compressive stresses developed by the rapid re-oxidation was considered to be a possible reason for the growth.

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Discontinuous precipitation in Cu-2.1 mass%Be alloy has been investigated by means of metallographic observations and microhardness measurements. The variation in volume fraction of discontinuous precipitation cells and cell radius with ageing time, and number of cells per unit volume have been determined by quantitative metallographic measurements of the specimens aged at temperatures from 473 to 773 K.
Upon ageing above 623 K, the growth rate (G) of cells decreases and the interlamellar spacing (l) in cells increases with ageing time progressively after the linear growth rate of cells. These phenomena may be attributed to the influence of continuous precipitates (plate-like γ′ precipitates), which take place in grain center regions where cells have not developed, on the cell growth. Below 573 K, continuous precipitates (fine γ′ precipitates) form prior to the discontinuous precipitation but the variation in G and l with ageing time is not observed.
The volume fraction of discontinuous precipitation cells, f, can be represented by Johnson-Mehl’s equation: f=1−exp(−btⁿ), where t is the ageing time and b and n are constants, and 2.2 above 623 K and 1.4 below 573 K are obtained as n’s values in the range of ageing times that G’s are linear. Above 623 K, the nucleation sites of cells are considered to be grain boundary edges according to Cahn’s theory. The number of cells in the n=1.4 regions is several times larger than that in the 2.2 regions. These phenomena may be attributed to the influence of the elastic strain resulting from the formation of G.P. zones and fine γ′ precipitates prior to the discontinuous precipitation upon cell nucleation.
From the dependence of the linear growth rate of cells on the ageing temperature, 115 kJ/mol is obtained as the apparent activation energy for cell growth.

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Compression tests have been made on well characterized Ni₃Fe single crystals over the temperature range 77 to 830 K in order to obtain systematic yield stress data comparable with well established data on Cu₃Au single crystals. Below room temperature the fully ordered Ni₃Fe has a lower yield stress than the disordered Ni₃Fe, as has been generally observed in various ordered alloys. It is demonstrated that strength peaks in ordered Ni₃Fe appear both at an intermediate temperature below T_c and just below T_c. The strengthening mechanism in the former is compatible with the Brown mechanism, and that in the latter is due to disordering as is the case with Cu₃Au. In contrast, the increase in flow stress with increasing temperature of ordered Cu₃Au at lower temperatures reported in literature is attributable to the thermally activated cross slip from {111} to {100} planes. Based on the phase stability concept, the differences in strength behavior between Ni₃Fe and Cu₃Au can be interpreted in terms of the differeces in APB morphology, i.e., the anisotropy of APB energy.

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Surface damage of stainless steels caused by bombardment of 20 keV helium ions was investigated by examining surface topography of irradiated samples by scanning electron and optical microscopy. Blister formation was observed in all samples of Cr, Fe, Ni, Fe-12%Ni alloy, type 316 stainless steel and double phase stainless steel DP 3 by irradiation with a fluence of about 1×10²² ions/m² at 373 K, though the blister radius and the blister density were somewhat different among the sample metals and the grain orientations.
The radiation effect was most pronounced in stainless steels, and the surface structure changed in the following stages with increasing fluence: 1. Blister formation, 2. blister rupture, 3. disappearence of blister covers and exfoliation of the surface layer, and 4. sponge-like structure without any traces of blister formation.
High temperature irradiation accelerated the surface changes and finally produced a very rough sponge-like structure which is considered to be the equilibrium structure upon further irradiation. Although general behavior of blister formation of the two stainless steels (316 SS and DP 3) is found to be almost independent of their microstructure, the surface unevenness was more clearly seen in DP 3. This was attributed to the difference in erosion yield (due to sputtering) between the ferrite phase and the austenite phase.

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The magnetic properties of the whole ternary alloy system of V–Cr–Mn with disordered bcc structure were investigated by means of X-ray diffraction, thermalexpansion, electrical resistivity and magnetic measurements. The concentration dependence of Néel point on antiferromagnetism and of Curie point and the saturation moment on weak ferromagnetism discovered in Cr–Mn alloys were examined. The magnetic phase diagram was established together with the boundary of the occurrence of localized moment in the Mn atom. From the standpoint of itinerant antiferromagnetism, taking account of the volume effect and the localized electrons, we found a linear relation between the effective itinerant electron concentration and the corrected Néel point. Some discussions about the appearance of the magnetic phases are given in connection with the relation between the local electronic states of the Mn atom and the band structure.

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The orthogonal dry cutting of commercial pure aluminium plates was made to study the effect of cutting conditions on residual stress distributions in the cut surface, and the plastic strain in the cut surface was measured by the Moiré method for the specimens with different cutting conditions and with sudden stop of cutting. As the results: the residual stresses by cutting are apt to be tensile in the surface and to be compressive in the inner part, and the Moiré strain in the cut surface is tensile in the cutting direction and compressive in the depth direction. On the other hand, at the cutting, the large strain of plastic tension is produced in the portions in front of the cutting edge of the tool. This primary strain and the secondary plastic deformation due to the progression of cutting edge strongly influence the residual stress.

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Nonequilibrium phases such as amorphous, chi (χ), epsilon (ε) and austenite have been found in Fe–X–C (X=Cr, Mo or W) ternary alloys quenched rapidly from the melts. The completely amorphous phase is formed in the composition ranges of 27–50 at%Cr and 14–20 at%C for Fe–Cr–C, of 6–27 at%Mo and 13–22 at%C for Fe–Mo–C, and of 10–14 at%W and 18–20 at%C for Fe–W–C. The high amorphous-forming tendency of these alloy systems seems to be due mainly to a remarkable increase of the glass transition temperature by the addition of chromium, molybdenum or tungsten, reflecting in strong-attractive interactions between carbon and alloy elements. The χ and ε phases are solid solutions containing large amounts of carbon and alloy elements, and their formation regions are located near the alloy compositions where the average group number of metallic atoms is in the vicinity of 7 and 7.7, respectively. The χ phase has a complicated bcc structure and its lattice parameter increases from 0.892 to 0.905 nm with increasing carbon and alloy contents. The ε-phase is a hcp structure with a lattice parameter of about a=0.27 nm and c=0.43 nm. The austenite phase has an ultra-fine grain size of about 0.2 μm and appears in the composition ranges of about 5–10 at%C and 4–30 at%Cr, 4–13 at%Mo or 2–8 at%W. The formation of this phase seems to become easy by the combination of three factors of the suppression of phase transformations in the solid state, the increase in solid solubility of carbon and alloy elements and the lowering of the MS point by dissolution of these elements.

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