Mechanical Properties of ODS Fe Alloys Produced by Mechano-Chemical Cryogenic Milling

Abstract

s An α-Ferrite (Fe) powder dispersed with 4 vol.% of Al 2 O 3 was successfully produced by a simple miling at 210 K with a mixture of Fe 2 O 3, Fe and Al ingredient powders, followed by 2 step high temperature consolidation: Hot Pressing (HP) at 1323 K and then Hot Isostatic Pressing at 1423 K. The microstructure of the consolidated material was 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 pure Fe matrix with a grain size of ~20 nm and Al 2 O 3 with a bimodal size distribution of extremely fine (~5 nm) and medium size dispersoids (~20 nm). The mechanical properties of the consolidated materials were characterized by compressive test and micro Vickers hardness test at room temperature. The results showed that the yield strength of the ODS (Oxide Dispersion Strengthened) Fe alloy are as much as 674 ± 39 MPa and the improvement of the yield strength is attributed to the presence of the fine Al 2 O 3 dispersoid.