Formation of In-Situ Dispersion Strengthening Particles in Cast FeCrAl Alloy

In order to fabricate dispersion strengthened alloys strengthened by submicron-sized or nano-sized stable particles through casting routes, understanding of the formation process of dispersion strengthening particles in metal melt is of significance. Thus, nano NiO and TiO2 particles were selected as reactant to form in-situ dispersion strengthening oxide particles in Fe20Cr5Al alloy. Nano NiO and TiO2 particle powder was separately dispersed into nano Ni powder first. The loose mixed nano powder was added in Fe20Cr5Al alloy melt when pouring the melt into mold. The study shows that nano NiO particles were not as effective as nano TiO2 particles in forming dispersion strengthening Al2O3 particles. The final diameters of dispersion strengthening oxide particles arose from nano TiO2 particles were of submicron. The Brownian collision of particles had caused this coarsening.