The influence of phosphorus on the microstructure and stress-rupture properties in a low thermal expansion superalloy

The influence of phosphorus on the microstructure and stress-rupture properties of IN783 alloy, the newly developed low thermal expansion superalloy, was investigated. Addition of phosphorus markedly promotes the precipitation of β-NiAl phase which improves the intergranular oxidation resistance of high P-doped alloys. However, phosphorus segregation deteriorates the interfacial cohesion of intergranular β/γ matrix and induces many intergranular cracks. Consequently, the stress-rupture life is reduced in high P-doped alloys.