Abstract The present work describes the solidification behavior of alloys Ni-29Fe-18 W (A1), Ni-29Fe-18W-5Co (A2), Ni-29Fe-18W-10Co (A3) and Ni-10Fe-30W-16Co (A4) and corresponding solidification reactions have been proposed. The alloys A1, A2 and A3 display typical dendritic microstructure while the alloy A4 exhibits the presence of sub-grains within high angle grain boundaries. The segregation coefficient (k′) values of all the alloying elements have been calculated from electron probe micro analyzer data and utilized to explain partitioning behavior of the alloys during solidification. The elements W, Co and Ni, Fe tend to segregate at dendritic and interdendritic regions in alloys A1, A2 and A3, respectively. The alloy A4 exhibits the predominant partitioning of Fe at sub-grain boundaries. Primary solidification product in all the alloys is fcc γ phase. The appearance of W-O particles in interdendritic region of alloys A2 and A3 is due to non-dissolution of the same in liquid while W precipitation occ...