Microstructure Evaluation of New ODS Alloys with Fe-Al Matrix and Al2O3 Particles

ODS steels are used for their very good mechanical properties at high temperature and low-cost production in comparison with other super alloys (ex. nickel super alloys). The paper describes a new group of Fe-Al Oxide Dispersion Strengthened (ODS) alloys with fine Al2O3 precipitates. ODS ferritic steels are high temperature creep resistant materials, which are intended to be applied more in the future industry. The steel was prepared by powder metallurgy under mechanical alloying and hot consolidation. To describe the stability of this material, annealing with different temperatures and holding times were carried out. The results show that the fine-grained microstructure is stable during long-term annealing up to 800 degrees C. At temperatures over 1000 degrees C, the grain structure coarsens by abnormal grain growth by keeping the size of oxides unchanged. Besides, the grain structure of the material is improved by differing the annealing time and temperature. The obtained structures were analyzed by optical and scanning electron microscopy. The mechanical properties and hardness were measured by tensile test at different temperatures.