The　impurity　formation　energies　of　the　sigma　and　gamma　phases　of　Ni-based　single　crystal　superalloys　doped　with　W,　Cr　and　Co　in　different　sublattices　have　been　investigated　using　first-principles　based　on　the　density　functional　theory.　The　bonding　characteristics　of　the　doped　a　phase　were　analyzed　with　the　valence　charge　densities　and　the　density　of　the　states.　The　results　of　the　calculations　indicated　that　the　typical　refractory　element　W,　which　has　a　large　atomic　size,　preferentially　partitions　into　the　sigma　phase　due　to　the　nature　of　the　bonding　and　the　unique　crystal　structure　with　close-packed　planes　and　large　interstitial　spaces.　In　addition,　the　site　preference　of　refractory　elements　in　gamma　phase　was　in　the　order　of　W,　Cr　and　Co.　(C)　2014　Elsevier　B.V.　All　rights　reserved.