Kinetic Effect-Dependent Seaweed Formation in Single-Crystal Al-2 Wt Pct Si Alloy by Laser Surface Remelting

In this study, we investigated the effect of kinetic on seaweed pattern formation in an Al-2 wt pct Si alloy during laser surface remelting. Our findings showed that the cellular pattern growth could be linked to the strong anisotropy of the interface energy in the (100)[001]_0 deg and (100)[001]_15 deg orientations. However, at a small but finite interface energy anisotropy of the (100)[001]_45 deg orientation, degenerate seaweed can prevail under a scanning velocity of 10 mm/s. A 3D finite element numerical model of combined processing parameters showed that a high-temperature gradient (~10⁶ K/m) promoted the formation of degenerate seaweed. As the scanning velocity increased, the effects of interface kinetics and the interface energy are comparable, causing a transition from the degenerate to hyperbranched seaweed. Furthermore, in the (111)[01-1]_0 deg orientation, where the interfacial energy was nearly isotropic, the interface kinetics can become dominant and govern the seaweed cells growing along the scanning direction. Graphical Abstract: [Figure not available: see fulltext.].