PhasesandmicrostructuresofthreehighZncontainingAl–Zn–Mg–Cualloyswereinvestigatedbymeansofthermodynamiccalculationmethod,opticamicroscopy（OM）,scanningelectronmicroscopy（SEM）energydispersivespectroscopy（EDS）,X-raydiffraction（XRD）,anddifferentialscanningcalorimetry（DSC）analysis.TheresultsindicatethatsimilardendriticnetworkmorphologiesarefoundinthesethreeAl–Zn–Mg–Cualloys.Theas-cast7056aluminumalloyconsistsofaluminumsolidsolution,coarseAl/Mg（Cu,Zn,Al）2eutecticphases,andfineintermetalliccompoundsg（MgZn2）.Bothofas-cast7095and7136aluminumalloysinvolvea（Al）eutecticAl/Mg（Cu,Zn,Al）2,intermetallicg（MgZn2）,andh（Al2Cu）.Duringhomogenizationat450°C,fineg（MgZn2）candissolveintomatrixabsolutely.Afterhomogenizationat450°Cfor24h,Mg（Cu,Zn,Al）2phasein7136alloytransformsintoS（Al2CuMg）whilenochangeisfoundin7056and7095alloys.ThethermodynamiccalculationcanbeusedtopredictthephasesinhighZncontainingAl–Zn–Mg–Cualloys.
