Rapid solidification of Al-Si alloys using differential fast scanning calorimetry

Abstract

Tailoring microstructures and properties in metal alloys, e.g., in additive manufacturing, requires a deep understanding of its rapid solidification behavior. However, in many rapid solidification processes, in-situ investigations are difficult due to the lack of accurate measurements of cooling rates and nucleation undercooling. This study used differential fast scanning calorimetry (DFSC) to investigate the rapid solidification of micro-sized Al-Si alloy particles, with compositions including Al-Si1, Al-Si10, Al-Si12, and Al-Si20 (mass%), by employing controllable cooling rates ranging from 100 K/s to 95,000 K/s. Based on the analysis of nucleation undercooling and microstructure, the solidification sequence and different mechanisms of the α-Al phase formation were proposed. A modified model using classical nucleation theory (CNT), including surface heterogeneous nucleation, and interface/bulk heterogeneous nucleation for α-Al is employed. This study presents a practical approach to examining the rapid solidification behavior of metal particles, allowing the distinction between surface and interface/bulk nucleation.