Effect of Si on microstructure and mechanical properties of Fe-based ultrafine eutectic composites

Addition of Si into a Fe70Ni15B15 ultrafine eutectic composite has a significant influence to modulate the microstructure to bimodal eutectic structure comprising lamellar- and irregular-type eutectic by suppressing the formation of the micron-scale dendrites upon solidification. The (Fe70Ni15B15)94Si4 bimodal eutectic composite presents considerably enhanced plasticity of ∼13% with high strength of ∼1520 MPa. The rotational motion of the spherical eutectic colony is considered to be a crucial factor to effectively dissipate shear localization thus improving the plastic deformability.