Taking　5E83　alloy　(Er　and　Zr　mieroalloyed　5083　alloy)　as　tested　material,　the　effects　of　Er　and　Zr　microalloying　elements,　grain　size,　deformation　temperature　and　strain　rate　on　superplasticity　of　the　alloy　were　investigated　by　means　of　superplastic　tensile　test,　scanning　electron　microscope　(SEM),　electron　backscatter　diffraction　(EBSD)　and　transmission　electron　microscope　(TEM).　Through　recrystallization　annealing,　air　cooling　and　water　cooling　friction　stir　processing　(FSP),　the　grain　sizes　of　7.　4,　5.2　and　3.　4　(xm　were　obtained,　respectively,　and　used　as　the　initial　state　for　superplastic　stretching.　The　results　show　that　the　smaller　the　initial　grain　size,　the　higher　the　superplastic　elongation.　When　the　grain　size　is　greater　than　5　(xm,　the　grain　coarsening　is　slow　during　superplastic　deformation,　and　refining　the　initial　grain　can　significantly　improve　superplasticity.　However,　when　the　grain　size　is　less　than　5　jxm,　grain　coarsening　is　serious　during　superplastic　deformation,　and　further　refinement　of　initial　grain　has　limited　effect　on　superplasticity.　The　superplastic　tensile　results　at　different　temperatures　and　strain　rates　show　that　when　the　temperature　is　in　range　of　450-540　°C　and　the　strain　rate　is　in　range　of　1.　67　X　10-4　-1.　67　X　10-1　S-1,　the　superplastic　elongation　first　increases,　then　decreases　and　then　increases　with　the　increase　of　temperature　and　strain　rate.　Under　the　condition　of　temperature　of　520　°C　and　strain　rate　of　1.　67　X　10-3　S-1,　the　water-cooled　FSP　alloy　obtains　the　largest　elongation　of　330%　corresponding　to　grain　boundary　slip　superplastic　deformation　mechanism.　The　addition　of　Er　and　Zr　significantly　improves　the　superplasticity,　which　is　mainly　due　to　the　formation　of　nano-dispersed　Al3(Er,　Zr)　phase　in　Al　matrix　that　can　pin　the　grain　boundary　and　hinder　the　migration　of　the　grain　boundary　during　superplastic　stretching.　When　the　grain　size　is　greater　than　5　(im,　the　Al3(Er,　Zr)　phase　effectively　inhibits　the　grain　growth　thus　improving　the　superplasticity.　©　2023　Chinese　Mechanical　Engineering　Society　of　Heat　Treatment.　All　rights　reserved.