Nowadays,　the　events　of　bacterial　infection　are　increasingly　arising.　It　is　urgent　to　develop　new　antibacterial　material　to　fight　against　the　bacteria　having　resistance　to　drug.　Because　the　antibacterial　stainless　steels　have　both　antibacterial　property　and　other　excellent　combination　ones,　their　development　has　been　obtained　rapidly.　At　present,　the　copper-containing　antibacterial　stainless　steels　are　the　research　focus.　It　has　been　reached　that　the　antibacterial　effect　of　those　materials　is　due　to　the　copper-rich　phases　precipitated　from　the　matrix　by　aging　treatment.　Most　of　studies　were　performed　at　single-phase　stainless　steels,　but　rarely　at　duplex　stainless　steels.　It　is　necessary　to　study　the　precipitation　process　of　copper-rich　phases　in　duplex　stainless　steels　for　the　development　of　antibacterial　duplex　stainless　steels.　In　this　work,　the　microstructure　and　precipitating　evolution　law　of　copper-rich　phases　in　the　copper-containing　duplex　stainless　steels　during　antibacterial　aging　treatment　has　been　analyzed　in　detail　by　SEM,　XRD　and　TEM.　The　results　indicate　that　antibacterial　copper-　rich　phases　are　precipitated　from　ferrite　and　α/γ　interfaces,　no　precipitation　in　austenite　when　the　duplex　stainless　steels　are　aged　at　temperature　ranging　from　540　to　580°C.　The　technique　parameters　of　the　aging　treatment　have　important　effect　on　the　volume　fraction　and　morphologies　of　precipitated　phase.　With　aging　time　increasing,　the　precipitates　coarsen,　and　their　morphologies　gradually　change　from　spherical　particle　to　rod-like　or　long-stripe-like　grain.　When　the　aging　temperature　is　raised,　precipitation　speed　of　copper-rich　phases　accelerates　and　they　make　the　change　like　before.　At　the　same　time,　the　copper-rich　phases　gradually　turn　from　metastable　state　to　steady　Ε-Cu　phase　with　the　composition　close　to　pure　copper,　which　has　complicated　multilayer　structure　with　twisting　layers.　The　Kurdjumov-Sachs　orientation　relationships　between　Ε-Cu　phases　and　the　ferrite　matrix　followed:　(1¯11¯)Ε-Cu//　(1¯1¯0)α-Fe,　[011]Ε-Cu//[001]α-Fe,　(111¯)Ε-Cu//(1¯21¯)　α-Fe,　[011]Ε-Cu//[012]α-Fe.　©　Copyright.