An experimental investigation on the kinetics of solute driven remelting

Interface Formation During Fusion™ Casting of AA3003/AA4045 Aluminum Alloy Ingots

“…Epitaxial growth of a-Al, initially with a planar, but quickly transforming to a cellular and then dendritic solidification morphology from the AA3003 into the AA4045 (in Figure 23(a)), was typically seen at the interface. This is qualitatively similar to interfaces seen in dissolution studies [6,32,33] as well as the aluminum brazing literature. [34] Mn-rich intermetallics, both polyhedral in shape (Figure 23(b)) and script-like in shape (Figure 23(c)), were found on the AA4045 side of the final interface (identified with SEM-EDS).…”

“…First, as seen in Figures 21 and 22 at the final as-cast AA3003/AA4045 interface, up to 1 mm of the AA3003 was removed by solutal dissolution by the molten AA4045, similar to observations by Caron et al [5] Additionally, the as-cast interface looked qualitatively similar to interfaces obtained in (i) solute driven remelting studies of aluminum in Al-Mg alloys by Dutta and Rettenmayr [32] and (ii) pure aluminum dissolution rate studies in Al-Si melts conducted by Craighead et al [6] Mn-bearing intermetallics were also found on the AA4045 side of the interface, suggesting that AA3003 dissolution took place and locally increased the Mn content of the liquid AA4045 in the vicinity of the interface prior to final solidification. Furthermore, semi-spherical-shaped scallops at the interface were observed in both macro-etched samples, Figure 21, as well as in optical metallographs, Figure 22.…”

Remelting-induced anomalous eutectic formation during solidification of deeply undercooled eutectic alloy melts

“…This means that the primary solid that comprises the central part of the branch becomes superheated and will be partially remelted since temperature recalescence is completed within a very short time, and it is impossible for the primary solid to adjust its composition immediately by solid-state solute diffusion. One can understand the reason for this behavior from the experimental work of Dutta and Rettenmayr [18]. Putting an Al solid in contact with an Al-Mg liquid, they found that remelting would take place so long as the solid and liquid compositions at the interface were out of equilibrium, and an increase in the liquid solute supersaturation would lead to an increased driving force for remelting.…”

Conduction-limited crystallite melting

“…The glass ''stinger,'' which appears clearly in the upper part of the lower video frames is 1 mm in diameter. non-equilibrium melting of alloys that provide experimental observations and theoretical analysis of melting phenomena where solute diffusion plays a key roˆle [25][26][27][28].…”