In order to clarify the effects of neutron irradiation on the ageing characteristics of copper-beryllium alloys with or without small amounts of additional elements, the changes in electrical resistivities, micro-Vickers hardness, tensile properties, electron microstructures and selected area diffraction patterns were measured during ageing after irradiation with about 1∼4×10¹⁷ nvt at reactor ambient temperature. It was found that the enhancement of G. P. zone formation during irradiation occurred in supersaturated alloys, and the dissolution of G. P. zones formed and the enhancement of γ′ precipitation occurred during subsequent ageing. On the basis of the experimental results, the mechanism of these effects are discussed relating the interaction with the atoms of the third elements.

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The influence of high hydrostatic pressure on the flow stress of polycrystals of high-purity copper (OFHC) and of tough pitch copper (TPC) has been studied at room temperature and compared with that obtained with pure aluminium polycrystals which has already been reported by the authors. Pressurizing under pressures up to 15000 kg/cm², tensile tests at atmospheric pressure and under 12000 kg/cm² using the differential pressure method, and tensile tests under a constant hydrostatic pressure of 12000 kg/cm² have been carried out. Results obtained are as follows: (1) Pressurizing up to 15000 kg/cm² gives no effect on the flow stress of OFHC copper at atmospheric pressure. As for TPC, a remarkable increase of flow stress at atmospheric pressure is observed at the beginning of deformation after pressurizing under 12000 kg/cm². The increase of the flow stress falls rapidly with increasing strain and becomes almost zero at about 40% strain. The repeated pressurizing during tensile testing has the same effect as that due to the pressurizing applied only once before deformation. (2) The change of flow stress observed by the differential pressure method with the pressure difference between atmospheric pressure and 12000 kg/cm² is about 2.2% for OFHC copper and about 2.6% for TPC. The change in OFHC copper agrees with that in the shear modulus of copper measured by Lazarus. (3) Tensile tests under a constant pressure of 12000 kg/cm² show that the flow stress of OFHC copper increases by about 2% at the beginning of the deformation and by about 5.5% under about 15% strain or more as compared with that at atmospheric pressure. As for TPC, the change in the flow stress is approximately expressed as a sum of the amount measured for OFHC copper and that due to the effect of pressurizing for TPC.

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Corrosion cracking occurs in the commercial grades of austenitic stainless steel (18 Cr–10 Ni) when exposed to tensile stress and certain environments. An extensive study was undertaken to develope a steel resistant to stress corrosion cracking. The influence of phosphorus and nitrogen in austenitic stainless steels on stress corrosion cracking has been investigated in boiling MgCl₂ at 154°C by the U-bend and tensile methods. The results of the study showed the detrimental effects of phosphorus and nitrogen and the interaction of these elements on the sensitivity of the steels to stress corrosion cracking. A new stainless steel resistant to stress corrosion cracking can be developed by controlling the contents of phosphorus and nitrogen in 18 Cr–10 Ni stainles steel.
The results have been elucidated by observing the dislocation structures of these steels by measuring the general corrosion rates and potential-time relations in boiling MgCl₂ solution at 154°C.

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Aging behaviors of both isothermal and continuous heating of maraging stainless steels containing cobalt and molybdenum were investigated by resistivity measurements at liquid nitrogen temperature. The resistivity change during aging, which is in good agreement with that of the specific heat previously measured by the authors, may be due to the appearance and redissolution of the solute rich-zones. In addition, these behaviors are scarcely affected by the presence of molybdenum, which is considered to be a hardening element. Isothermal resistivity decreases rapidly in the earliest stage of the rich-zone formation. After this stage there is a much slower reaction which proceeds over a period of time corresponding to the precipitation hardening stage. The reversion curve experimentally obtained can be considered as a resultant combination of two component curves: one giving an initial increase in resistivity due to the true reversion, and the other of decreasing resistivity due to the rich-zone formation of solute remaining in the solid solution even after the preaging treatment. Only in the earliest stage, the low-temperature aging is steadily suppressed by cold work prior to aging.

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Crystal structures and magnetic properties of Au–Mn–Sb alloys have been investigated by means of X-ray and magnetic analyses. It has been found that an intermetallic AuMnSb compound of the Cl_b type exists in the Au–Mn–Sb system and forms a solid solution in the narrow compositional range which has lattice parameters of about 6.368∼6.377₅ Å at room temperature. The AuMnSb compound has a lattice parameter of 6.373Å at room temperature, and its reciprocal susceptibility satisfies the Curie-Weiss law. From this relationship, the paramagnetic effective Bohr magneton number per Mn atom and the paramagnetic Curie temperature have been determined to be 5.98 and 98°K, respectively.

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The relation between the casting structure and sliding wear properties of lead and tin as the major components of lead-bronze was investigated. The test pieces were cut out from the chilled, columnar and equi-axial structures of lead-bronze ingots of different composition and were slid on a hardened steel ring in air without any lubricant.
The results obtained are as follows:
(1) The equi-axial crystal part in the casting structure shows the best wear resistance properties, followed by the columnar crystal, and the chilled crystal is the worst generally. These trends are remarkable in the high lead and high tin alloy.
(2) The worn surfaces of the chilled structure are always metallic and the wear phenomenon is severe. The surfaces of columnar crystals are metallic or oxidized. The degree of oxidation depends on the compositions and sliding conditions, and is not satisfactory as compared with the equi-axial crystals. The surfaces of the equi-axial crystals are easily oxidized and the amount of wear is very small, while the wear of the steel ring is often severe.
(3) It is considered that the wear of lead-bronze is influenced by the distribution and shape of lead and the contents of lead and tin. The size of lead in the equi-axial crystal structure is relatively large and its distribution is relatively continuous each other. This form of lead is more preferable for wear resistance than the fine and isolated form of lead in the chilled structure.
(4) The materials with stable oxidizing wear seize the mating steel and show a high coefficient of friction, and these phenomena are relaxed by a suitable addition of lead.

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Drawability of metal sheets is indicated by Swift’s L. D. R., C. C. V. of Fukui’s test, and the plastic strain ratio r. Swift’s L. D. R. and C. C. V. of Fukui’s test are based on the deep drawing test, while the plastic strain ratio r is determined simply by the tensile test. It has been reported by many investigators that these values are excellent indicators of drawability. But it is difficult in practice to indicate the drawability of thin sheets by Fukui’s test and the plastic strain ratio r. On the other hand, Swift’s test is favorable for thin sheets, but in addition to the complexity to determine the L. D. R. of metal sheets, the reproducibility of the value obtained is doubtful.
So in this paper the validity of the load deep drawing method was discussed, where the value is indicated by the ratio of fracture load in the cup wall to the maximum load to deform the flange. Although the fracture load must be kept constant irrespective of the drawing ratio, the observed values are at variance, and therefore L. D. R. of metal sheets cannot be determined by this so-called T. Z. P. method. But it has been found that the fracture loads of the cup wall in various drawing ratios can be kept constant by a suitable lubricating operation, thus enabling the load deep drawing method to determine the drawability of thin metal sheets.

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Transmission electron microscopy and electron diffraction studies were carried out in order to make clear the crystallograsphic properties of strengthening precipitates in an 18% Ni maraging steel. The primary precipitates observed in specimens in the maximum hardness state were rod in shape, the size being about 25 Å in width and 500 Å in length. The length directions of the rod precipitates were parallel to the ⟨111⟩ direction of the matrix, and the crystal structure was identified as the orthorhombic Ni₃Mo intermetallic compound. The orientation relationship between the Ni₃Mo precipitate and matrix was proposed possibly to be
(010)_Ni3Mo⁄⁄(011)_α′, [100]_Ni3Mo⁄⁄[1\bar11]_α′,
that is, the closest packed plane and direction in precipitates were parallel to those in the matrix, as observed in many other precipitation phenomena. When the ordering of atoms in the Ni₃Mo crystal was disregarded, the crystal could be described in terms of the hcp lattice and the relationship was represented by the Burgers relationship which is well known in the bcc to hcp phase transformation. The length direction of Ni₃Mo precipitates, ⟨111⟩_α′, was verified to be the [1\bar11]_α′ direction involved in the above orientation relationship.
The interfacial coherency between the Ni₃Mo precipitate and the matrix was examined referring to the orientation relationship and the length direction. The hexagonal Ni₃Ti phase was also detected as the secondary precipitates.

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Effects of supercooling and cooling rate on the solidified structures of Al–Mn, Al–Cr and Al–Zr alloys, which had a strong tendency to form metastable solid solution by rapid cooling of the molten alloys, were investigated by means of thermal analysis and microscopic observation. The results obtained were as follows:
(1) The square of the degree of supercooling was proportional to the cooling rate on the solidification of the alloys having a solute concentration up to the maximum solid solubility limit at equilibrium (Ce). At solute concentrations higher than Ce, this relation was satisfied under the conditions that the primary crystals were a super-saturated solid solution.
(2) The minimum cooling rate to form the super-saturated solid solutions containing more solute atoms than Ce was 115, 175 and 190°C/sec for Al–Mn, Al–Cr and Al–Zr respectively.
(3) Metastable phase diagrams were proposed under varying conditions of composition, temperature and cooling rate in the Al–Mn, Al–Cr and Al–Zr systems.

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The interfacial transition from the plane to the cellular structure and the segregation pattern of Al–Cu alloys were investigated by means of a quenching method during unidirectional solidification.
The following results were obtained: (1) The preferred grain boundary segregation occurred prior to the breakdown of the planar interface. (2) Small holes appeared at random on the solid-liquid interface at the biginning of the transition. (3) The holes were aligned or distributed regularly to form an elongated cell. (4) The solidification proceeded entrapping the liquid phase at the bottom of the holes and resulted in the “rosary-like segregation”. (5) The “rosary-like segregation” was also observed in hexagonal cell nodes.
These phenomena can hardly be explained by the constitutional supercooling or by the M–S theory. In the current paper these were discussed in terms of the stability of the small pits on the solid-liquid interface.

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