Thermal stability of Al-Mg-Sc-Zr alloy

The thermal stability of Al-3(Sc,Zr) precipitates in the cold worked Al-Mg-Sc-Zr alloy after elevated temperature exposure was investigated. The evaluation was conducted using room temperature tensile, Vicker's hardness, optical metallography and scanning electron microscope (SEM) with the backscatter. The results show that the Al-3(Sc,Zr) precipitates and mechanical properties have no obvious change, and the grains keep elongated along the working direction as that in cold worked sample after exposure at 300 degrees C for 1 000 h. The coarsening of Al-3(Sc,Zr) precipitates occurs and is no longer effective on the recrystallization resistance, and partial recrystallization is observed after 400 degrees C exposure. In particular, after 500 degrees C exposure, the hardness decreases drastically and the alloy has fully recrystallized due to the obvious coarsening of Al-3(Sc,Zr) precipitates.