Formation of intermetallic phases in unrefined and refined AA6082 Al alloys investigated by using SEM-based ultramicrotomy tomography  

作　　者：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 

机构地区：[1]Shagang School of Iron and Steel and High-Performance Metal Structural Materials Research Institute,Soochow University,Suzhou 215137,China [2]School of Materials,The University of Manchester,Sackville Street,Manchester M139PL,UK [3]Chinalco Materials Application Research Institute Co.Ltd.,Beijing 102200,China [4]Helmholtz-Zentrum Berlin Für Materialien und Energie,Hahn-Meitner-Platz 1,Berlin 14109,Germany [5]Key Laboratory of Electromagnetic Processing of Materials,Ministry of Education,Northeastern University,Shenyang 110819,China

出　　处：《Journal of Materials Science & Technology》2022年第25期118-128,共11页材料科学技术（英文版）

基　　金：financially supported by the EPSRC(No.EP/N007638/1);the 2021 Jiangsu Shuangchuang(Mass Innovation and Entrepreneurship)Talent Program(No.JSSCBS20210702)。

摘　　要：The spatial arrangement,distribution and morphology of Fe-bearing intermetallics in AA6082 alloys depends 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 casting,(b)Al-5 Ti-1 B grain refiner addition and(c)intensive melt shearing has been investigated by threedimensional visualization using SEM-based serial ultra microtomy tomography.The formation sequence of phases in AA6082 alloys is generally categorized into four stages:formation ofα-Al grains,Fe-bearing intermetallics,Mg_(2)Si phase,and eutectic rosettes.Results of three-dimensional visualization of the microstructure indicated that TiBparticles not only could nucleate Fe-bearingβ-intermetallics,but also could provide substrate for the formation of Fe-bearingα-intermetallics and Mg_(2)Si.A further deep analysis reveals that the essential condition for the formation of secondary phases such as Fe-bearing intermetallics and Mg_(2)Si phase is the build-up of a supersaturated solute front at theα-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-bearingα-intermetallics.However,the intensive melt shearing is a better manufacturing process because the intermetallics are more evenly distributed and refined than with the addition of the grain refiner,thereby improving the properties of the alloy.

关 键 词：Al-Si-Mg alloy Grain refinement Al-Fe-Si intermetallic phase TOMOGRAPHY Ultramicrotomy MG2SI 

分 类 号：TG146.21[一般工业技术—材料科学与工程]