Microstructure Evolution of High Undercooled Fe-Ni-P-B Eutectic Alloy

The high undercooled Fe-Ni-P-B eutectic alloy was obtained by glass fluxing technique.The evolution of microstructures at different undercoolings was researched.The results show that the solidification structure gradually transforms from regular rod eutectic to granular anomalous eutectic with the increase of undercooling.When the undercooling is lower than 35 K,the rod regular eutectic refines gradually.When the undercooling ranges between 35 K and 150 K,the structure is composed of regular eutectic and anomalous eutectic.When the undercooling exceeds 150 K,complete anomalous eutectic is obtained.The formation of different structures can be explained by J-H model and dendrite remelting.