The optimization of heat treatment and chemical composition for Inconel 718 alloy has been investigated uninterruptedly because of its excellent mechanical properties and metallurgical workability.The species , chemical compositions and content of equilibrium phases of Inconel 718alloy in the temperature range of 600-1 100℃ were calculated by using thermodynamic software " Thermo-Calc " and the latest relevant datebase of Ni-base superalloys.A concept of elemental partitioning fraction was used to study the partitioning characteristics of alloying elements in each equilibrium phase at different temperatures , such as Ni , Cr , Fe , Nb , Mo , Al , Ti and C , and some calculation results were confirmed under a scanning transmission electron microscope ( STEM ) .The results showed that the elemental partitioning characteristics with the change of temperature revealed the selective partitioning characteristic of alloying elements in equilibrium phases at different temperatures , such as Nb was mainly distributed in δ and γ′phase , C in carbides , Al and Ti in γ′phase and Cr , Mo in Laves phase.At the same time , the effect of the change of component and quantity for each precipitated phase on matrix phase can be helpfully understood , which provided a theoretic foundation to optimize the chemical composition and heat treatment in different environments for Inconel 718alloy.
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