Assessment of the Microstructure and Solidification Characteristics of Al–20%Mg2Si Composite under Melt Superheating Treatment Using Thermal Analysis

The influence of melt superheating treatment on the solidification characteristics and microstructure of Al–20%Mg2Si in-situ composite has been investigated. The results revealed that melt superheating temperature has a significant effect on solidification parameters and morphology of primary Mg2Si particles. Solidification parameters acquired using cooling curve thermal analysis method, indicate that both nucleation temperature and nucleation undercooling of primary Mg2Si particles increase by increasing melt superheating temperature, while recalescence undercooling decrease under the same condition. Also, based on the microstructural evaluations, melt superheating treatment can refine primary Mg2Si particles and alter their morphology from dendritic shape to more spherical shape and the eutectic microstructure of a-Al + Mg2Si becomes finer and the distance between eutectic layers becomes smaller.