Precipitation of nanosized DO22 superlattice with high thermal stability in an Ni–Cr–W superalloy

It is demonstrated for the first time that a nanoscale superlattice with a DO22 structure can precipitate in an Ni–Cr–W alloy by means of a simple ageing treatment at 700 °C. The existence of tungsten in the superalloy stabilizes the DO22 superlattices, which are transient metastable phases in Ni–Cr–Mo alloy. Because of the fine, spherical and dispersed precipitates in the Ni–Cr–W matrix, the microhardness of the alloy is improved remarkably.