| Abstract Scope |
Real-time imaging provides unique opportunities to directly reveal phase evolution during alloy processing. Here, we combine high-temperature confocal scanning laser microscopy, thermodynamic modeling, phase-field simulations, and advanced microstructural characterization to investigate impurity-induced phase formation in scrap-derived FeCrAlTiSi multicomponent alloys. In-situ observations capture the dynamic precipitation of Ti(C,N) particles during solidification and directly validate thermodynamic predictions of phase evolution. The impurity-derived particles act as effective grain-boundary pinning centers during homogenization, suppressing abnormal grain growth while enabling dissolution of brittle grain-boundary intermetallics. The experimentally observed solidification sequence and particle evolution agree closely with CALPHAD and phase-field simulations, providing a mechanistic understanding of impurity-controlled microstructure development. Compared with alloys produced from high-purity raw materials, the scrap-derived alloy achieves substantially lower material cost and CO₂ footprint while maintaining refined microstructures and multifunctional performance. This work demonstrates how real-time imaging can uncover dynamic phase transformation mechanisms and guide sustainable alloy design through controlled impurity engineering. |