In critical components such as aircraft engines, the performance and stability of high-temperature alloys directlyimpact component safety and efficiency. Through long-term thermal exposure experiments conducted at 700 and 1 100 ℃on fully heat-treated DD10 single-crystal superalloys, this study systematically investigated the volume fraction,morphological characteristics, and evolution mechanisms of the γ′ strengthening phase (size, morphology, distribution) andtopologically close-packed (TCP) phases under different aging temperatures and durations. The results indicate that during700 ℃ thermal exposure, only slight coarsening of the γ′ phase occurs along the dendrite trunks and interdendritic regions,with no TCP phase precipitation detected. As the thermal exposure temperature increases to 1 100 ℃, the morphology ofthe γ′ phase in the alloy significantly changes. After 200 h of thermal exposure at 1 100 ℃, the γ′ phase morphologytransforms from a regular cubic configuration to an irregular form, resulting in the formation of a rafted structure. Withprolonged thermal exposure time, the rafted structure gradually coarsens. Additionally, with increasing temperature, thesegregation of refractory elements induces the precipitation of the μ phase. During thermal exposure at 700 and 1 100 ℃,the difference in the lattice constant between the γ and γ′ phases decreases with increasing temperature, and the absolutevalue of the degree of misfit between the two phases also diminishes accordingly. After 200 h of thermal exposure at700 ℃, the degree of misfit is slightly greater than that in the as-heat-treated state, and the cubicity of the γ′ phase reachesits maximum at this point.