The spatial arrangement,distribution and morphology of Fe-bearing intermetallics in AA6082 alloys de-pends on the manufacturing process of the alloy and thus influences the macroscopic properties.Here,the microstructure of a near industrial scale casting AA6082 Al alloy fabricated by:(a)direct chill cast-ing,(b)Al-5Ti-1B grain refiner addition and(c)intensive melt shearing has been investigated by three-dimensional visualization using SEM-based serial ultramicrotomy tomography.The formation sequence of phases in AA6082 alloys is generally categorized into four stages:formation of α-Al grains,Fe-bearing intermetallics,Mg2Si phase,and eutectic rosettes.Results of three-dimensional visualization of the mi-crostructure indicated that TiB2 particles not only could nucleate Fe-bearing β-intermetallics,but also could provide substrate for the formation of Fe-bearing α-intermetallics and Mg2Si.A further deep anal-ysis reveals that the essential condition for the formation of secondary phases such as Fe-bearing in-termetallics and Mg2Si phase is the build-up of a supersaturated solute front at the α-Al solid-liquid interface irrespective of the specific nucleation site.In addition,the results indicate that grain refinement processing causes the severe interconnectivity of Fe-bearing α-intermetallics.However,the intensive melt shearing is a better manufacturing process because the intermetallics are more evenly distributed and re-fined than with the addition of the grain refiner,thereby improving the properties of the alloy.

J.M.Yu;T.Hashimoto;H.T.Li;N.Wanderka;Z.Zhang;C.Cai;X.L.Zhong;J.Qin;Q.P.Dong;H.Nagaumi;X.N.Wang

Shagang School of Iron and Steel and High-Performance Metal Structural Materials Research Institute, Soochow University, Suzhou 215137, China;School of Materials, The University of Manchester, Sackville Street, Manchester M13 9PL, UK;Chinalco Materials Application Research Institute Co. Ltd., Beijing 102200, China;Helmholtz-Zentrum Berlin Für Materialien und Energie, Hahn-Meitnner-Platz 1, Berlin 14109, Germany;Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China

材料科学技术（英文版）

[1]J.M.Yu;T.Hashimoto;H.T.Li;N.Wanderka;Z.Zhang;C.Cai;X.L.Zhong;J.Qin;Q.P.Dong;H.Nagaumi;X.N.Wang-.Formation of intermetallic phases in unrefined and refined AA6082 Al alloys investigated by using SEM-based ultramicrotomy tomography)[J].材料科学技术（英文版）,2022(25):118-128

ultramicrotomy,rosettes,crostructure,termetallics

Formation,phases,unrefined,AA6082,alloys,investigated,using,tomography,spatial,arrangement,distribution,morphology,bearing,intermetallics,pends,manufacturing,thus,influences,macroscopic,properties,Here,microstructure,near,industrial,scale,casting,fabricated,direct,chill,5Ti,1B,refiner,addition,intensive,melt,shearing,been,three,dimensional,visualization,serial,formation,sequence,generally,categorized,into,four,stages,grains,Mg2Si,eutectic,Results,indicated,that,TiB2,particles,not,only,could,nucleate,also,provide,substrate,further,deep,anal,ysis,reveals,essential,condition,secondary,such,build,supersaturated,solute,front,solid,liquid,interface,irrespective,specific,nucleation,site,In,results,refinement,processing,causes,severe,interconnectivity,However,better,because,are,more,evenly,distributed,than,thereby,improving

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