Assessment of 3D inhomogeneous microstructure of highly alloyed aluminium foam via dual energy K-edge subtraction imaging

Abstract

X-ray microtomography was used to evaluate the inhomogeneous characteristics of newly-developed Al–Zn–Mg foam. Using the synchrotron K-edge subtraction technique, a highly heterogeneous distribution of Zn was quantified three-dimensionally (3D) in the cell wall of as-cast foam. Time-resolved analysis of the concentration evolution revealed a tendency to a homogeneous Zn distribution as solution time prolonged. This was accompanied by a declined variation in hardness measurement. Other microstructural features after solution treatment, such as number and size distribution of micropores, were also characterised. By utilising various quenching rates, the inhomogeneities in microstructure and compression properties inside the foam were also clarified. Thus, element-sensitive tomography provides a novel solution for the 3D/4D analysis in the study of foams.

Keywords:

• metallic foam
• K-edge subtraction
• inhomogeneity
• element distribution
• mechanical properties

Acknowledgements

The synchrotron radiation experiments were performed at the SPring-8 with the approval of JASRI (No. 2007A1431, 2008B1147 and 2009B1374). The work was partly supported by the Grant-in-aid for Scientific Research (No. 17360340) from the Japan Society for the promotion of Science (JSPS). The authors gratefully acknowledge Dr. Tetsuji Miyoshi, Shinko Wire Company Ltd., for providing the foam material. One of the authors (QZ) would also like to thank the support of JSPS through a Postdoctoral Research Fellowship program.