Abstract
In metallographic study of Ni-20Cr-20W alloy specimens creep ruptured at temperatures of 900 and 1000°C in air, it has been observed that a β-Mn type nitride, π-phase, is formed in contact with α2-W phase precipitated on grain boundary in the vicinity of intergranular cracks. The appearance of the π-phase in the nitrogen free Ni-Cr-W alloy is mainly attributed to the nitrogen in air through the intergranular cracks. And no decreases in creep resistance and rupture elongation were observed due to the precipitation of π-phase.
