Recalescence effect simulation and microstructure evolution of undercooled Fe₈₂B₁₇Si₁ alloy

Eutectic alloys (e.g. Fe-B-Si) as important casting alloys are the most commonly used material in industrial production. Fe-B-Si eutectic alloy is a kind of soft magnetic materials, has the very important application prospect in the market. In the past few decades, research on eutectic solidification alloys has achieved important results. The microstructure evolution, nucleation and growth theory of Fe-B-Si eutectic alloy under non-equilibrium condition have been perfected. But the recalescence effect on microstructure evolution has not been accurately described theoretically. The microstructure evolution of undercooled Fe₈₂B₁₇Si₁ alloy in the obtained undercooling range ΔT=6~280 K were investigated by employing the glass fluxing technique in combination with cyclical superheating. The cooling curves of solidification process were fitted in combination of break equation and JMAK model, and the calculated results were consistent with the evolution of pattern of organization and microstructure of Fe₈₂B₁₇Si₁ eutectic alloy. When 6 K≤ΔT<75 K, Fe₈₂B₁₇Si₁ alloy was made of complex rules eutectic and eutectic mixture of quasi regular eutectic. When 75 K≤ΔT<180 K, the solidification microstructure was composed of a mixture of eutectic and deeply undercooled irregular eutectic. When 180 K≤ΔT<250 K, the solidification microstructure consists of primary a-Fe phase as well as the irregular eutectic among dendrite. When ΔT>250 K, the solidification structure was completely non-eutectic organization.