抄録
Explosive compaction experiments have been performed on water atomized Fe-25Cr-5Al heat resisting alloy powders and an optimum compaction condition was determined. Compactions were made using cylindrically axi-symmetric direct method. The ratio of explosive mass to powder mass (E/M ratio) was changed from 2.75 to 4.5 to vary the compaction pressure and duration time. At E/M ratio less than 3.0, the center of the cylindrical compact was not consolidated. When E/M ratio was over 4.5, a hole and cracks were formed in the compact because of the convergence of the shock wave and the interference of the reflected waves. An optimum E/M ratio was determined between 3.5 and 4.0, where no cracks were formed in the compacts. The specific density ratio of the compact reached 98% under that conditions. Although the tensile strength of as-compacted material was 12 kgf/mm2, the tensile strength was increased to 80 kgf/mm2 by post sintering treatment. Oxidation behavior of the explosively compacted material was comparable to melted and forged material, and superior to conventionally sintered and hot pressed materials. Hardness of the explosively compacted material in the temperature range from 400°C to 1000°C represented higher value than that of the melted and forged material. This result and the high tensile strength mentioned above suggested that the powder boundaries were strengthened by dispersed oxides crashed from the initial powder surface during explosive compaction.
