Aged martensites in a Cu-12.9 mass%Al-2.5 mass%Mn shape memory alloy have been studied by means of electron microscopy and diffraction and X-ray microanalysis. On ageing an 18R type martensite at 573 K, very small coherent and spherical precipitates are homogeneously formed throughout the martensite. These very small precipitates are evolved by banishing Cu atoms into the martensite matrix. In accordance with such composition variance in the martensite matrix, M_s and A_s temperatures increase on ageing. In connection to the formation of very small precipitates, the 18R martensite gradually varies the crystal structure to a 2H one. Plate-like precipitates are also observed in the martensite matrix at early stages of ageing, which are of a DO₃ structure and rich in Al content. Orientation relationship and habit plane of the plate-like precipitates to the martensite matrix are similar to those of thermoelastic martensites to the β₁ matrix in Cu–Al alloys. At late stages of ageing, equilibrium γ phase appears in a block shape, and the plate-like precipitates with a DO₃ structure are observed in contact with the γ phase.

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The oxidation mechanism of molten Al–Mg alloys was studied by means of a thermal balance, X-ray diffraction and EPMA. Oxides produced in the Al–Mg (2–12%) alloys oxidized at 923 K to 1173 K for 10.8 ks (3 h) were MgO or/and MgAl₂O₄. MgO was produced in an early stage of oxidation, and its amount increased temporarily and then decreased gradually. MgAl₂O₄ increased gradually in amount with decreasing amount of MgO. The oxidation reactions were indicated by the equations, Mg+1/2O₂→MgO and MgO+2Al+3/2O₂→MgAl₂O₄, which were the consecutive reaction. MgO was produced in the form of granules around pores opened to the alloy surface and was irregularly distributed near the surface of the molten alloy. MgAl₂O₄ crystallized into a spinel structure from amorphous oxide and formed a homogeneously mixed layer composed of the fine oxide particles and metal.

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The determination of sulfur in ferroalloys, iron ores and pig irons by the isotope dilution method using ³⁴S enriched sulfur, combined with spark source mass spectrometry, was studied. This method is based on a conventional gravimetric method. Samples were dissolved in nitric and hydrochloric axid containing potassium chlorate and the spike solution which was prepared by dissolving elemental ⁴³S in nitric acid, and potassium chlorate was added to the solution. For ferrosilicon and high-carbon ferrochrome samples, they were fused with sodium carbonate or sodium carbonate and sodium peroxide. The resulting solution was evaporated to dryness. These salts were dissolved in hydrochloric acid, and metallic zinc was added to reduce ferric ions to ferrous ions. Barium chloride was added to the solution to precipitate sulfur as barium sulfate, and then the precipitate was filtered and ignited. The ignited residue was mixed with graphite powder and pressed into electrodes.
The method was applied to the determination of sulfur in the JSS, NBS and BCS standard samples, and the results with satisfactory precision and accuracy were obtained for the analyzed samples except for ferrosilicon samples. The poor precision for ferrosilicon seems to be due to the blank of sulfur from reagents (Na₂O₂, etc.) used.

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The permanent magnetic properties of Fe-34–67.5 at%Pt alloys have been investigated. It is found that the magnetic properties of an Fe-38.5 at%Pt alloy quenched from the disorder phase γ (fcc) region and subsequently aged at 773 K (500°C) for 360 ks (100 h) in the ordered phase γ₁ (fct, L1₀-type) region, are B_r=1.08 T (10.8 kG), H_c=340 kA·m⁻¹ (4.3 kOe) and (BH)_max=159 kJ·m⁻³ (20 MG·Oe).
X-ray analysis and microstructural observations indicate that the magnetic hardening is due to the ordering stage from the γ phase to the γ₁ phase having a high crystal magnetic anisotropy.

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Microstructural changes near the coherent spinodal line during ageing in Fe–18.5 and 19.2 at%Mo alloys were investigated by means of transmission electron microscopy. A mixed microstructure of the ⟨100⟩ modulated structure and the plate-shaped Mo-rich zones was observed in the alloys aged at a temperature just above the coherent spinodal temperature, T_s. With further ageing this morphological distinction became obscure, and consequently the modulated structure appeared. When the alloy was aged at a higher temperature, the plate-shaped zones were only nucleated on the {100} matrix planes, while the ageing at a temperature just below T_s only produced a typical ⟨100⟩ modulated structure. A series of results implies that the microstructures produced near T_s become continuously inhomogeneous with increasing ageing temperature, which has been proposed by Binder.

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The present paper deals with the reaction of the potassium titanate fiber on four kinds of pure metals (aluminum, nickel, titanium and copper) in air and vacuum at elevated temperatures, in order to find the applicability of the fiber to MMC. Results obtained are summarized as follows: (1) The fiber does not react on the aluminum matrix up to the melting point of the matrix. Beyond the point, however, it is found by EPMA line analysis that potassium in the fiber disappears. (2) Up to 1123 K, there is no detectable reaction between the fiber and the nickel matrix. (3) The fiber dose not react in vacuum on both titanium and copper matrices below the melting point of them, while a violent reaction between the fiber and the matrices occurs in the atmosphere at temperatures higher than 1023 K. The above mentioned results suggest that the potassium titanate fiber can be applied as a reinforcement in the aluminum and nickel matrices when the MMC is fabricated in air, as well as in the titanium and copper matrices when fabricated in vacuum.

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