HWANG Seung Joon Daejin University

Microstructure of Nanocrystalline Fe Dispersed with Al2O3

An α-Ferrite with 4 vol.% of Al2O3 nano composite was successfully produced by a simple miling at 210 K with a mixture of Fe3O4, Fe and Al ingredient powders, followed by subsequent consolidation: Hot Pressing (HP) and then Hot Isostatic Pressing (HIP) at 1423 K. The microstructure of the consolidated materials were characterized by standard metallographic techniques such as XRD(X-ray Diffraction), TEM and STEM-EDS. The results of STEM-EDS analysis showed that the HIPed materials comprised a mixture of Fe matrix with a grain size of 1 μm and Al2O3 with a bimodal size distribution of extremely fine (~ 5 nm) and medium size dispersoids ( ~20 nm). The mechanical properties of the materials were characterized by compressive and micro Vickers hardness test at room temperature. The results showed that yield strength of the nano composite materials is much higher than a pure Fe which was consolidated from powder for a comparison. The improvement of the mechanical properties are attributed to the presence of the fine and medium size dispersoid.

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