Effect of Er and Si co-microalloying on mechanical properties and microstructures of AlCuMg alloys

The effect of Er and Si on the evolution of precipitates in Al–Cu–Mg alloys during elevated temperature exposure was investigated. The Er segregation in θ′-Al2Cu precipitates and Si/Mg co-segregation at the interfaces of θ'/Al matrix are experimentally observed in Al–Cu–Mg–Si–Er alloy, which finally contributes to the heat resistance of the Al–Cu–Mg–Si–Er alloy. Si enhances formation of the Q″ phases as nucleation sites for the θ′ phases, resulting in a refined distribution of θ′ phases. Al–Cu–Mg alloy with high strength as well as high thermal stability is obtained by co-adding Er and Si. The high-temperature yield strength (YS) of Al–Cu–Mg–Si–Er alloy at 225 °C are increased by 37 MPa compared with that of Al–Cu–Mg alloy. Simultaneously, the addition of Er significantly increases the elongation of Al–Cu–Mg–Si–Er alloy.