On the ternary eutectic reaction in the Fe 60 Cr 8 Nb 8 B 24 quaternary alloy

Recently a Fe 60 Cr 8 Nb 8 B 24 quaternary amorphous/nanocrystalline composite coating has been successfully synthesized by high velocity oxygen fuel in our group. The composite coating shows excellent wear and corrosion resistance. In order to understand the phase evolution of the quaternary alloy during cooling and interpret its good glass forming ability, the stable phases in the as-melted ingot of the same composition were studied by X-Ray diffraction, scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry. Thermodynamic calculation was performed based on a database compiled from literature. The calculated results show good agreement with the microstructural observation. It was found that Fe 60 Cr 8 Nb 8 B 24 alloy lies very close to the eutectic point of the system, which is related to its high glass forming ability. The thermodynamic calculation could provide insightful understanding and guidance for the future amorphous composition designing in Fe-Cr-Nb-B quaternary system.