Achieving significant grain refinement in industrially oriented Al-Mg-Si-Fe alloys using a scalable special cooling medium

The sub-rapid solidification (SRS) process is a self-quenching system enabling rapid solidification and unique microstructure evolution. This technique provides a cost-effective approach for the industrially oriented production of high-performance Al-Mg-Si-Fe alloys. In this study, a scalable copper mold, assisted by a special cooling medium (solid-Tin), was successfully developed, achieving enhanced undercooling and a cooling rate of 10 ³ °C/s. The TEM microstructure analysis of the tested alloys revealed a uniform, highly refined microstructure with a dense network of grain boundaries and minimal coarse intermetallic phases, including globular primary α-Al grains, finely dispersed Al₃Sc precipitates, and AlFeSi intermetallic phases. The refined microstructure results in a notable improvement in mechanical strength, achieving tensile strengths of up to 298 MPa. This work presents a scalable and effective pathway for producing fine-grained aluminum alloys with improved mechanical properties, offering valuable insights for the next generation of lightweight structural materials.