The Optimization of Mechanical Alloying Conditions of Powder for the Preparation of a Fe-10Al-4Cr-4Y2O3 ODS Nanocomposite

Abstract

Mechanical alloying (MA) of powders represents the first processing step in the production of oxide dispersion-strengthened (ODS) alloys. MA is a time and energy-consuming process also in the production of Fe-10Al-4Cr-4Y2O3 creep and oxidation-resistant ODS nanocomposite, denoted as the FeAlOY, and it deserves to be optimized. MA is performed at two different temperatures at different times. The powder after MA, as well as the microstructure and high-temperature strength of the final FeAlOY, are characterized and the optimal MA conditions are evaluated. The obtained results show that the size distribution of the powder particles, as well as the dissolution and homogenization of the Y2O3, becomes saturated quite soon, while the homogenization of the metallic components, such as Al and Cr, takes significantly more time. The high-temperature tensile tests and grain microstructures of the secondary recrystallized FeAlOY, however, indicate that the homogenization of the metallic components during MA does not influence the quality of the FeAlOY, as the matrix of the FeAlOY is sufficiently homogenized during recrystallization. Thus, the conditions of MA correspond to sufficient dissolution and homogenization of Y2O3 and can be considered the optimal ones.

Formation and Microstructural Evolution of Ferritic ODS Steel Powders during Mechanical Alloying

“…Recent explanations state that severe fragmentation of Y 2 O 3 particles drives them into amorphous sub-particles, making them undetectable to XRD [ 41 , 42 ]. Other authors also found that homogenization of Y 2 O 3 in ODS steel during MA was achieved quickly, whereas for metallic components it took much more time [ 43 ]. Figure 16 shows the XRD pattern of the low intensity Zr and Y 2 O 3 reflections obtained after initial mixing of powders (1 min of MA).…”