Sub-micrometre holotomographic characterisation of the effects of solution heat treatment on an AlMg7.3Si3.5 alloy

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• 作者：D. Tolnai^a ; ^b ; ^{domonkos.tolnai@hzg.de} ; G. Requena^a ; P. Cloetens^c ; J. Lendvai^b ; H.P. Degischer^a
• 关键词：Synchrotron tomography ; Aluminium alloys ; Coarsening ; Mechanical characterisation ; Cast Al&ndash ; Mg&ndash ; Si alloys
• 刊名：Materials Science and Engineering ; A
• 出版年：2012
• 期刊代码：61_09215093
• 类别：ms
• 出版时间：30 July, 2012
• 卷：550
• 期：Complete
• 页码：214-221
• 文件大小：1653 K

摘要

A strip cast AlMg7.3Si3.5 alloy is investigated by sub-micrometre holotomographic analysis achieving a voxel size of (60 nm)³ by cone beam magnification of the focused synchrotron beam using Kirkpatrick-Baez mirrors. The three-dimensional microstructure of the same specimen volume in the as-cast state is compared with that after exposure to 540 掳C for 30 min resolving microstructural features down to 180 nm. The three-dimensional analysis of the architecture of the eutectic Mg₂Si and the Fe-aluminides reveals how the as-cast microstructure changes during the solution treatment. The alloy in the as-cast condition contains a highly interconnected seaweed-like Mg₂Si eutectic. The level of three-dimensional interconnectivity of the Mg₂Si eutectic phase decreases by only partial disintegration during the heat treatment correcting the two-dimensional metallographic impression of isolated round particles. Statistical analyses of the particle distribution, sphericity, mean curvatures and Gaussian curvatures describe quantitatively the architectural changes of the Mg₂Si phase. This explains the decrease of the high temperature strength of the alloy by the solution treatment tested in hot compression.