This paper deals with the sintering mechanism of iron powder compacts containing nickel. Nickel-coated iron powder by electroless plating and iron powder mixed with carbonyl nickel powder are used. The shrinkage during sintering is examined using the theory of liquid phase sintering. In the case of coated powder, the circumferential diffusion of iron through the nickel layer of constant thickness is the rate controlling step, and the shrinkage is independent of nickel content. In the case of mixed powder, the thickness of diffusion layer is dependent on nickel content, and the shrinkage is also dependent on nickel content. The activation energy for the sintering process is about 48, 000cal/mole.

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In the manufacture of 13 Cr stainless steel powder by atomization using high velocity water jet, the influence of components in the melt upon particle shapes and properties was investigated. The results can be summarized as follows;
1) Increasing the silicon content in the melt reduces the amount of oxygen in the powder and leads to the powder of low apparent density. The optimum amount of silicon to be added is in the range of 0.5 to 0.7% by weight.
2) The oxygen content and apparent density of the powder increase with increasing manganese content, and, therefore, it is desirable that the amount of manganese is no more than 0.15%, for the containing 0.5-0.7% of silicon. The amount of silicon should be increased to the melt with a high manganese content.
3) The addition of carbon and nickel up to 0.15% and 0.5% respectively has little effect on the oxygen content and apparent density of the powder.
4) The high hardness of the as atomized powder leads to poor pressing properties, and so the powder atomized should be annealed before pressing.

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Cemented carbides containing 15 vol.% of Co and 10 wt.% of TaC or TiC in total carbides were vacuum-sintered and two kind of specimens having different carbon content respectively in each alloy were obtained. Some properties of these alloys affected by low temperature annealing at 700°C and 800°C were mainly studied in comparison with those of straight WC-Co alloys to get an information on the influences of TaC or TiC in the cemented carbides. Brief conclusions of this experiment were as follows: (1) Transverse-rupture strength and magnetic saturation of the alloys containing TaC or TiC increase with increasing of carbon content of the alloys, in the phase range corresponding to two phase range of straight alloys, but on the contrary, hardness, specific resistivity and lattice constant of the binder phase decrease. (2) After annealing, rupture strength, specific resistivity, magnetic saturation and lattice constant of the binder decrease and the change of these properties is in general remarkable in low carbon alloys than in high carbon. (3) The phenomena above mentioned are in good agreement with those of WC-Co straight alloys. So the change of properties by annealing is considered also due to the fact that the W atoms highly dissolved in the binder phase of low carbon alloys precipitate during the course of the anealing, as already reported on the WC-Co alloys. (4) The rate of the precipitation, however, will decrease by the addition of TaC or TiC to the WC-Co alloys.

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