The effect of tungsten content on the properties of L1₂-hardened Co–Al–W alloys

Highlights: • Microstructure and properties of Co-base superalloys can be changed significantly by changing the W content. • W partitions to the γ′ phase but to a lesser extent than Nb, Ti and Ta. • Co-base superalloys exhibit a positive mismatch between Co matrix and γ′ precipitates up to 900 °C. • W additions increase the γ′ phase fraction and solvus temperature. • The rafting direction of γ′ particles after creep is in accordance with the positive lattice mismatch. - Abstract: Ternary Co–Al–W alloys with W contents between 8 and 11 at.% were investigated with respect to element partitioning, γ′ solvus, γ′ volume fraction, lattice mismatch and creep properties. W is enriched in the γ′ precipitates and an increasing W content stabilizes this phase. The lattice mismatch is positive up to 900 °C and rafting occurs during creep with a preferred direction in accordance with this positive lattice mismatch