Synthesis of aluminum oxide dispersed α-Fe with nano sized grains by simple milling

Aluminum oxide (with 4 volume% of Al2O3) dispersed α-Fe (BCC) with nano-sized grain was synthesized by reactive-cryogenic milling with a mixture of the elemental Fe, Al and Fe3O4 (Magnetite) powders as a reactant. Prior to the Hot Isostatic Press (HIP) for further densification of the materials, the milled powders were hot pressed (HPed) at the elevated temperature. The microstructure of the consolidated materials was characterized by standard metallographic techniques such as TEM (Transmission Electron Microscopy), STEM-EDS (Energy Dispersive Spectroscopy), and XRD (X-ray Diffractometer). Mechanical properties of the materials were determined by compressive yield test and micro Vickers hardness test at room temperature. The grain size estimation was attempted for the materials by XRD, using the Scherrer formula and TEM pictures. The microstructure of the materials was comprised with a mixture of a homogeneous distribution of Fe and Al2O3 nano grains. The 0.2% off-set yield strength and micro Vickers hardness of the materials were as high as 824 ± 39 MPa and 3.70 ± 0.1 GPa, respectively.