Minoru Otaguchi

Improvement in elongation of sintered Fe–Cu alloy by chemical reduction of the surface of rapidly solidified powder

Abstract The effect of oxide inclusions on the tensile properties of a Fe–Cu consolidated alloy was investigated. Fe–Cu powders with a copper content in the range of 0.5–5 mass% were prepared by high-pressure water atomization and reduced in a hydrogen atmosphere to remove surface oxides. The as-atomized and reduced powders were consolidated by groove rolling at 973 K. Microstructures were characterized by scanning electron microscopy and tensile properties were determined. The microstructure where recrystallized grains appeared was observed in the samples from both powders; there were fewer and smaller inclusions in the samples from the reduced powder. Reduction of the oxide inclusions contributed to increased elongation of the consolidated samples. Control of the inclusion at the powder surface is necessary in order to obtain plasticity.

Effect of Time of Heat Treatment on the Growth of Superconductive Phase of Bi-System Superconductor

The effect of the heat treating time is investigated to develop the fabrication technique of Bi system superconductor. A temperature just below the softening of the specimen is selected as a sintering temperature. The content of Pb additive is substituted for 20% of Bi. Various heating time and the growth of the superconducting phase are investigated. The measurements of the magnetic susceptibility, X-ray diffraction and SEM observation of the superconducting phase are carried out. From the results of the experiments to investigate the effect of heat treating time, the specimen with 300 hours of heat treatment time has most high Tc phase.