Age hardening and creep resistance of cast Al–Cu alloy modified by praseodymium

• Pr addition enhances the hardness and creep resistance of the Al–Cu alloy.
• Pr addition facilitates the formation of the θ′ precipitates.
• Pr addition results in the formation of the Al11Pr3 phase in the Al–Cu alloy.

The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al11Pr3 phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al11Pr3 phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modified alloy at elevated temperatures.