Precipitation evolution of Al–Zr–Yb alloys during isochronal aging

Precipitation strengthening in Al–Yb, Al–Zr and Al–Zr–Yb alloys aged isochronally between 100 and 550 °C was investigated. The Al–0.08 at.% Zr–0.03 at.% Yb alloy shows double-peak age strengthening behavior and obtains its second peak hardness of 379 MPa at 475 °C, which illustrates significant precipitation strengthening and thermal stability. The critical coherency transition radius of L12-ordered Al3(Zr,Yb) precipitates is larger than that of Al3Yb. The synergetic effect of Yb and Zr on the precipitation evolution in Al–Zr–Yb is discussed.