The effect of elevated temperature exposure on fracture resistance and fracture path in a precipitation strengthened aluminum alloy

The combination of TEM and quantitative electron fractography shows that the increase incidence of ductile intergranular fracture is associated with coarsening of grain boundary precipitates. Changes in the PFZ width, grain boundary precipitate number density and grain boundary precipitate size, coupled with matrix strength changes, govern the fracture resistance and crack path of the test alloy as a function of time and temperature of exposure. The triaxial stress state extant at crack initiation results in lower area fraction of IG failure than does fracture in less constrained stress states, as after 2 mm of crack growth.