Pouring Height Effects on Macro-Segregation and Electrical/Thermal Properties of Aluminium-Zinc Alloy
DOI:
https://doi.org/10.63746/njtd.v22i1.2710Keywords:
Aluminum-Zinc Alloy, Pouring Height, Macro-segregation, Microstructural Analysis, Thermal Conductivity, Electrical ConductivityAbstract
This paper investigated the effects of pouring heights on macro-segregation, electrical and thermal conductivity of an Aluminium–Zinc alloy. Al 5wt.% Zn was cast at pouring heights ranging from 100 to 500 mm. Analytical techniques like optical scanning electron and energy dispersive spectrometry were used to assess the extent of segregation. The electrical and thermal conductivities were estimated, utilising the Wiedemann-Franz Law. The thermal profile of the as-cast Al-5wt.% Zn revealed variations in solidus and liquidus reaction temperatures relative to position, attributed to local chemical composition variation and cooling rate. Notably, at a pouring height of 400 mm, the temperature field in the melt was more uniform, leading to enhanced melt flow motion and transformation of large primary α-Al grains into finer spherical grains, resulting in a more homogeneous microstructure. As a result, the Al-5wt.% Zn sample obtained at a pouring height of 400 mm exhibited the highest electrical and thermal conductivities (37 IACS and 133 W/mK), aligning well with established standards (33.8% IACS and 131 W/mK). Significantly, the magnitude of macro-segregation recorded at various pouring heights even at low concentrations of solute (5wt.% Zn) signifies that macro-segregation is strongly dependent on the process parameter (i.e., pouring height) and not just the solute concentration.
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