The　temporal　evolution　of　microhardness　and　Al-3(Er,Zr/Hf)　precipitates　are　investigated　in　Al-Er-Zr/Hf　alloys　during　annealing　at　450　degrees　C　and　500　degrees　C.　The　microhardness　of　the　alloys　decreases　continuously　with　the　prolonged　annealing　time　due　to　the　coarsening　of　the　precipitates.　Different　weakening　amplitudes　are　observed　because　of　the　disparity　of　the　precipitate　coarsening　rate　that　is　related　to　the　disparity　in　their　intrinsic　diffusivities　of　Er,　Zr,　and　Hf　solute　atoms　in　an　Al　matrix.　The　addition　of　Hf　element　is　beneficial　to　enhancing　the　coarsening　resistance,　thus　improving　the　thermal　stability　of　the　alloys.　Introducing　such　elements　to　improve　the　thermal　stability　of　precipitates　can　provide　a　new　idea　or　choice　for　the　development　of　heat-resistant　aluminum　alloys.