Partition behavior of alloying elements and phase transformation temperatures in Co-Al-W-base quaternary systems

► The phase equilibria between γ, γ′, χ, β and μ were determined in Co-Al-W-X systems. ► Ta, Nb, Ti are strong γ′ former elements rather than a γ former. ► The γ′ solvus temperature increases by the addition of the γ′ former elements. ► The ab initio formation energy of γ′, χ and β phases was calculated.