*Gamma (γ): This is the matrix phase. While Co-based superalloys are less-used commercially, alloying elements include C, Cr, W, Ni, Ti, Al, Ir, and Ta. As in stainless steels, Chromium is used (occasionally up to 20 wt.%) to improve resistance to oxidation and corrosion via the formation of a CrO passive layer, which is critical for use in gas turbines, but also provides solid-solution strengthening due to the mismatch in the atomic radii of Co and Cr, and precipitation hardening due to the formation of MC-type carbides.
* Gamma Prime (γ): Constitutes the precipitate used to strengthen the alloy. It is usually close-packed with a L1 structure of CoTi or FCC CoTa, though both W and Al integrate into these cuboidal precipitates. Ta, Nb, and Ti integrate into the γ phase and are stabilize it at high temperatures. 
* Carbide Phases: Carbides strengthen the alloy through precipitation hardening but decrease low-temperature ductility.
* Topologically Close-Packed (TCP) phases may appear in some Co-based superalloys, but embrittle the alloy and are thus undesirable.