同步辐射K边减影成像及其在多孔金属材料中的应用

基于元素吸收边附近两个能量上线性吸收系数存在差异,开发了同步辐射K边减影成像技术来标识元素的三维分布.采用略高于和略低于Zn元素K吸收边的能量分别成像,利用其减影像表征了Al-Zn-Mg泡沫铝材料中Zn元素的三维分布和定量化信息.铸态泡沫铝胞壁上Zn的空间分布不均匀,经过长时间固溶处理,Zn的偏聚情况减小;分析了该泡沫铝的断裂行为,发现其胞壁的脆性断裂与Zn元素的不均匀分布有关.研究结果表明,K边减影成像技术为材料三维组织定量表征提供了有力的分析手段.关键词：同步辐射K边减影成像元素分布三维表征

Synchrotron K-edge subtraction imaging and its application to metallic foams

On the basis of sudden change of linear absorption coefficient (LACs) in the vicinity of absorption edge, the synchrotron K-edge subtraction technique is developed to label the three-dimensional (3D) distribution of element. In this work, tomographic scans above and below the specific absorption edge of Zn are carried out and the subtracted image is used to identify and quantify the 3D distribution of Zn element inside the cell wall of Al-Zn-Mg foam. A non-uniform spatial distribution of Zn element is found in the cell wall of as-cast foam. After long solution tratment, the concentration of Zn element tended to be homogeneous. It is confirmed that the local agglomerated Zn-bearing particles exerta negative influence on the brittle cracking of the cell wall. The K-edge subtraction technique provides a powerful tool for the quantitative microstructure characterization of three-dimensional tissues.