Microstructural investigation of IN 939 superalloy

Abstract The vacuum cast nickel base IN 939 superalloy was investigated in the as-cast condition, as well as in the fully heat treated condition, i.e. after solution treatment followed by ageing. The alloy was characterized by optical microscopy, electron probe microanalysis and X-ray diffraction analysis. Volume fraction of the γ'-strengthening phase was determined by electrolytic phase extraction. The room and high temperature tensile properties and the Vickers hardness were determined for the as-cast and heat treated condition of the alloy. It was determined that the structure of the alloy consists of the γ-solid solution matrix, the γ'-intermetallic precipitate and various carbide phases. The simple heat treatment employed was shown to be effective in raising the γ' volume fraction and the yield and tensile stress.