High melting point metal based alloy material having high toughness and strength

Abstract

The present invention provides a refractory-metal-based alloy material having a remarkably enhanced toughness and strength, by internally nitriding a nitride-forming metal element incorporated as a solid solution into an alloy worked piece, which has a parent phase consisting of one element selecting from Mo, W and Cr, at a temperature equal to or lower than a recrystallization upper limit temperature of the worked piece to dispersedly yield ultra-fine nitride particles to the worked piece and thereby raise a recrystallization lower limit temperature of the worked piece, and then subjecting the internally nitrided worked piece to a second nitriding treatment at a temperature equal to or more than the raised recrystallization lower limit temperature, wherein at least in the surface region of the worked piece has a structure in which ultra-fine nitride precipitated particles are grown and stabilized with keeping the worked structure of the worked piece.