Abstract
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.
基金项目
EPSRC(EP/N007638/1)
2021 Jiangsu Shuangchuang(Mass Innova-tion and Entrepreneurship)Talent Program(JSSCBS20210702)
Henry Moseley X-ray Imaging Facility at The University of Manchester()
NETL
NSTL
维普
万方数据