高融点金属間化合物(Nb<SUB>3</SUB>Al)のプラズマ溶解ガスアトマイズ

概要

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Rapidly solidified niobium aluminides (Nb<SUB>3</SUB>Al) have been studied to understand their ability as structural materials for ultra-high temperature applications. A new gas atomization process combined with plasma-skull-melting without any refractory, refractory metal and ceramic, has been developed to produce ultra-clean powders. In this process, named Plasma-Melt-Gas-Atomization (PMGA), a pouring nozzle for molten metal stream is made of water-cooled copper with a bottom hole. Rapidly solidified powders of Nb3Al have been successfully obtained. Mean diameter of the powders is around 100μm, and oxygen content is 300ppm. PMGAed powders of Nb-22at%Al mostly consists of supersaturated solid solution of Al in Nb (bcc), although cast ingot of same composition wholly consists of ordered A15. Because microstructure of powder is identical to melt-spun ribbon, solidification rate of PMGA can be considered very high.
社団法人粉体粉末冶金協会の論文