High creep resistance behavior of the cast Al–Cu alloy modified by nano-scale PrxOy

Creep behavior of the unmodified and modified cast Al–Cu alloys was investigated at temperatures from 393 to 483 K in the tension test. The creep resistance ability of the Al–Cu alloy modified by PrxOy is almost 3–5 times as high as that of the unmodified Al–Cu alloy, which is attributed to a large number of nano-scale θ′ precipitates with high thermal stability in the modified Al–Cu alloy restricting and impeding the dislocation movement during the creep. The induction of a threshold stress in the analysis leads to a stress exponent of 5, which suggests that the creep behavior of both the present alloys is associated with the lattice diffusion-controlled dislocation climb (n = 5).