To create the two phases a β stabilizing element in addition to niobium (Nb), for example molybdenum (Mo), chromium (Cr) or tantalum (Ta) (2), is often present and the alloys also contains around 11 to 18 at.% Nb. The Nb, with retained Al concentration, enhances most of the material properties, but could in too high concentrations increase the creep sensibility. Other alloying elements can be added to improve this performance and tailor the material properties. However, the most important thing is to maintain control of the microstructure (9).