Anomalous capillary flow of molten Al-Si alloy and macrosegregation

A comprehensive study of molten alloy capillary flow in the wetting/non-wetting wedge-tee configuration is presented. The horizontal Al2O3 substrate is non-wetting, while the vertical, Al-Mn alloy AA3003, is wetting. The braze alloy is a composite of an aluminum-silicon alloy (Al-10Si) with potassium fluoro-aluminate flux embedded. The purpose for selecting such a wetting/non-wetting configuration is for repair and construction in space by means of brazing. When capillary forces are not opposed by gravity, the spreading of a liquid braze may be controlled by a non-wetting surface.Specifically, we study: (i) the evolution of the free surface shape of a large melt mass in the gravity field, (ii) kinetics of advancing/receding triple lines and dynamic contact angles, and (iii) microstructure of the resolidified molten alloy on the substrates.The receding contact line exhibits a sudden withdrawal towards the corner, then a long-time stagnation before final equilibrium in the corner. In contrast to the typical monotonic evolution of the advancing contact angle, the receding contact angle features an anomalous non-monotonic behavior. The microstructure of the re-solidified sample features a phase macrosegregation.

Automated summary

This study focuses on the comprehensive investigation of molten alloy capillary flow in the wetting/non-wetting wedge-tee configuration. The horizontal substrate made of Al2O3 exhibits non-wetting behavior, while the vertical Al-Mn alloy AA3003 shows wetting behavior. The braze alloy used is a combination of an aluminum-silicon alloy (Al-10Si) with potassium fluoro-aluminate flux embedded. The purpose of this wetting/non-wetting configuration is for brazing in repair and construction in space.