The　temporal　evolution　of　the　Al-3(ErZr)　precipitates　is　investigated　in　Al-0.04Er-0.04Zr　and　Al-0.04　Er-0.08Zr　alloys　during　aging　at　elevated　temperature　of　450　and　500　degrees　C.　The　results　show　that　the　coarsening　behavior　of　the　precipitates　in　both　alloys　is　similar,　due　to　the　core-shell　structure　with　Zr　segregated　in　the　shell　of　the　Al-3(ErZr)　precipitates.　With　the　increase　of　the　amount　of　Zr　addition,　the　misfit　between　the　precipitate　and　the　Al　matrix　decreases,　consequently　the　coherency　transition　size　of　the　precipitates　in　Al-0.04Er-0.08Zr　is　larger　than　that　of　Al-0.04Er-0.04Zr.　After　aging　at　500　degrees　C　for　100　h,　some　of　the　precipitates　in　Al-0.04Er-0.08Zr　transform　to　D0(23)　structure　due　to　the　high　Zr/Er　ratio,　while　the　precipitates　in　Al-0.04Er-0.04Zr　keep　the　L1(2)　structure.　(C)　2013　Published　by　Elsevier　B.V.