The　effect　of　elemental　interactions　between　solute　elements　on　diffusion　in　Ni-X-Y　(X,　Y:　Al,　Ti,　Nb,　Ta,　Cr,　Co,　Mo,　W,　Re,　Ru)　systems　and　gamma＇-coarsening　in　model　Ni-based　superalloys　are　investigated　by　performing　first　principles　calculations　and　high-temperature　thermal　exposure　experiments.　The　ternary　interactions　are　important　for　the　diffusion　barrier　of　a　solute　in　Ni-X-Y　and　the　coarsening　rate　of　precipitates.　These　results　are　related　not　only　to　the　electronic　structure　but　also　to　chemical　bonding.　(C)　2017　Acta　Materialia　Inc　Published　by　Elsevier　Ltd.　All　rights　reserved.