NITRIDED Mo ALLOY WORKED MATERIAL HAVING HIGH CORROSION RESISTANCE, HIGH STRENGTH AND HIGH TOUGHNESS AND METHOD FOR PRODUCTION THEREOF

摘要

A nitrided Mo alloy worked material having high corrosion resistance, high strength and high toughness, characterized in that it comprises a base Mo alloy worked material and, dispersed in the inside thereof, fine nitride particles having been formed by the nitriding of a metal element capable of forming a nitride present in the inside of the Mo alloy worked material and, formed on the surface thereof, a Mo nitride layer having been formed by the nitriding of a worked structure or a recovered structure on the surface; and a method for producing the nitrided Mo alloy worked material which comprises subjecting an alloy worked material containing Mo as a base phase and at least one of Ti, Zr, Hf, V, Nb and Ta as a solute of a solid solution to an internal nitriding with gradually elevating temperatures, and then subjecting the resultant product to an external nitriding. The nitrided Mo alloy worked material is novel and exhibits satisfactorily high corrosion resistance and a high strength under an ultra-severe conditions, such as in a boiled conc. sulfuric acid solution (for example, an aqueous 75 % H2SO4 solution at 180°C), and further, has a high strength at an elevated temperature and also a high toughness at a low temperature, which properties have never seen in the conventional materials.