DaeHan Kim (1), JaeHwang Kim (2), Equo Kobayashi (1)
Materials Science and Engineering: A, 768, December 2019. DOI: 10.1016/j.msea.2019.138449

Keywords

Fe-intermetallic compounds, Three-dimensional microstructure, Fracture, Al-Si-Mg-Fe alloy

Abstract

A three-dimensional (3D) microstructure of Fe-intermetallic compounds (Fe-IMCs) was analyzed by means of xray tomography. 3D images were obtained to understand the internal structure of the Fe-IMCs in Al-Si-Mg-Fe alloys. A needle-shaped β phase appears in two-dimensional (2D) observations while platelet and irregular morphologies of the Fe-IMCs are identified in 3D investigations. The reconstructed microstructure was roughly crushed with 20% reduction rates and less broken parts of Fe-IMCs are observed, showing platelet and blunt morphologies. The combination of a large- and small-volume of the Fe-IMCs remained after a 60% reduction rate. The needle- and lateral-shaped of the Fe compounds were finely fragmented into the micro- and/or nano-scale at a 80% reduction rate. The average size of the Fe-IMCs is refined from 20.3 to 2.9 μm at the 80% reduction rate. The largest size of the Fe-IMCs is shortened from 85.5 to 21.3 μm. It is considered that fracture is affected by the length of the Fe-IMCs. Rapid cracks initiated around the fragmented Fe-IMCs at the reduction rate of 40% because the number of the Fe-IMCs is increased due to fragmentation. On the other hand, the harmful influenceof Fe-IMCs on elongation becomes positive when the length of the Fe-IMCs decreases to less than a critical size.

How Our Software Was Used

Dragonfly was used to display three-dimensional visualizations and analysis after importing reconstructed files.

Author Affiliation

(1) Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1-S8-18, Ookayama, Meguro-ku, Tokyo, 152-8552, Japan.
(2) Carbon and Light Materials Application Group, Korea Institute of Industrial Technology, 222, Palbok-ro, Jeonju-si, 54896, South Korea.