Method for reducing thermally induced porosity in a polycrystalline nickel-base superalloy article

摘要

A method is provided for reducing the tendency for thermally induced porosity within a &ggr;' precipitation strengthened nickel-base superalloy which has been processed to obtain a uniform and coarse grain microstructure. This method is particularly useful for forming components such as gas turbine compressor and turbine disk assemblies in which optimal mechanical properties, such as low cycle fatigue and creep resistance, are necessary for operating at elevated temperatures within a gas turbine engine. The method generally entails alloying a &ggr;' precipitation strengthened nickel-base superalloy to have a boron content of not more than about 0.02 weight percent, and then forming a billet by melting an ingot of the superalloy in an argon gas atmosphere and atomizing the molten superalloy using argon gas. The above atomizing technique encompasses both powder metallurgy and spray forming processes.