Relationships between magnetic properties and composition, raw materials, additives, sintering profiles and production process for Mn-Zn ferrite were investigated. The adequate selection of raw materials and processing parameters is a key of the control of microstructure and electromagnetic property. A new production method of ferrite raw material by spray roasting was developed. This method has some advantages such as high purity, low cost and simple process.
Mn-Zn ferrite with superior performance for power applications was obtained by this method.

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The swelling of cylindrical compacts, 10 mm(d)×10 mm (h) in size, was measured with a micrometer during each production process; after pressing at 2-8 t/cm² (196-784 MPa), after dewaxing at 500°C (773K) for 30 min, and after sintering at 900°C (1173 K) for 5-180 min.
Compacts pressed under higher pressures (588-784 MPa) swelled during sintering, while those pressed under lower pressures (196-392 MPa) shrank. Both the swelling and the shrinkage of compacts pressed with die-wall lubrication and sintered in cracked ammonia gas were larger than those of compacts pressed with powder lubrication or sintered in argon gas. Dimensional change during sintering was larger in swelling or smaller in shrinkage, in the pressing direction than in the lateral direction.
The sintering time for the swelling of electrolytic copper powder compacts in argon gas was longer than that of the compacts sintered in cracked ammonia gas or of the compacts made from atomized copper powder.

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The effect of eutectoid β stabilizing elements of Cr, Mn, Fe, Ni, Cu, and Si on the sintering characteristics and tensile properties of Ti powder compacts was investigated, and compared with the case of Co addition carried out in a previous paper.
The additional elements of Fe and Ni had the similar good effect on the densification of Ti powder compacts to the Co addition, where the sintered density ratios increased with additional amount of Fe and Ni. In the case of Si addition, the extremely high sintered density ratio of 99% was obtained for the 2 wt%Si specimen, while it decreased abruptly with increasing amount of Si for the specimens containing more than 4 wt%Si. The other specimens of Ti-X (X=Cr, Mn, Cu) also showed the decreasing tendency of sintered density ratios with increasing amount of additional elements.
As the results of the tensile test concerning about Ti-2%Fe, Ti-2%Ni, Ti-2%Si and Ti-2%Co whose density ratios were more than 98%, it was confirmed that Ti-2%Fe specimen showed the highest value of tensile strength. Though the elongation value of 8% obtained for the (α+β)-quenched Ti-2%Fe specimen was much lower than 14% of the (α+β)-quenched Ti-2%Co specimen, it could be possibly improved by changing the heat treatment in (α+β)-region.

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Static tensile properties of HIP'ed Ti-6A1-4V alloys after sintering at 1473 K for 3.6 ks by blended elemental powder metallurgy process were studied, and compared with those of HIP'ed Ti-6A1-4V powder compacts, made by Rotating Electrode Process (REP).
Metallographic and fractographic observations were also carried out by light and scanning electron microscopy, and X-ray energy dispersion analysis.
The tensile strength and ductility of HIP'ed Ti-6A1-4V alloy after sintering by blended elemental process using hydride-dehydride Kroll process sponge fines as the titanium source were clarified to be nearly the same as those of HIP'ed REP Ti-6A1-4V alloy. On the other hand, amarked ductility degradation was observed in the case of using Hunter process sponge fines as the titanium source, and it was confirmed that this behavior is closely related to the existing NaCI in the sintered compacts.

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Mechanical properties, cutting performance, etc., of WC-β(WC/TiC=70/30)-TaC-TiN-Co alloy (cobalt contents, 8-8.5%) sintered in vacuum and nitrogen (PN₂=2.7 kPa) were studied as a function of TiN/(TaC+TiN) ratios (named TiN ratios).
The grain size of βt(WC-TiC-TaC-TiN solid solution) decreased with increasing TiN ratios and it naturally more decreased in sintering in N₂, without change in the grain size of WC. The transverserupture strength, in particular, of HIP-treated alloy sharply increased with TiN ratios of more than 0.2. It was found that the resistance to oxidation of alloys was markedly improved with increasing TiN ratios.
The results of cutting tests showed that the fracturing and flank wear resistances were scarcely affected by TiN ratios, but the cutting performance of the alloy sintered in vacuum was always superior to that of the alloy sintered in N₂.

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The effects of dispersion and superficial application of various rare earth oxides (Y₂O₃, La₂O₃, CeO₂, Eu₂O₃, Gd₂O₃) on the isothermal oxidation of Fe-20Cr sintered alloy have been studied at 1373 K in air. The dispersion of these rare earth oxides reduced the oxidation rate but the effect on the oxidation rate was dependent on the kind of the dispersoid. That is, the dispersion of La₂O₃, Y₂O₃ and Gd₂O₃ greatly reduced the oxidation rate, while the effect of Eu₂O₃ dispersion was far less than that of the other rare earth oxides. The dispersion of rare earth oxides except for CeO₂ suppressed the spalling of the scale. The superficial application of rare earth oxides except for Gd₂O₃ also markedly reduced the oxidation rate. The superficial application of Gd₂O₃ as well as Al₂O₃ had a negligible effect on the oxidation rate.
In the case of alloys which showed lower oxidation rate single layered Cr₂O₃ scale was maintained stably and the formation of Fe₂O₃ scale outside the Cr₂O₃ scale was suppressed; whereas thick Fe₂O₃ scale grew outside the Cr₂O₃ scale on the alloys which showed larger mass gain. The results suggested that the rare earth oxides which induced into the Cr₂O₃ scale suppressed outward migration of Fe ions through the Cr₂O₃ scale.

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