Primary and secondary dendrite arm spacing in unidirectionally solidified Al-2%Cu

Abstract

In this study unidirectionally controlled solidification of AI-2%Cu alloy and the resulting dendritic morphology is investigated. First general information is given on given on solidificatior, then dendritic growth is studied thoroughly. In experimental work, Al-2%Cu has bpen solidified under controlled laboratory conditions. For this purpose, a unidirectional growth furnace and a drive system has been designed and constructed. With the aid of this system, desired temperature gradient(GL) and grcwth rate(R) has been obtainea. during the experiments. Using a GL range between 10-40 °C /cm and an R range between 1-50x10-3 cm/sec, dendritic morpnology has been obtained. The liquid-solid interface has been frozen during growth by guenching. The resulting growth surfaces have been cut perpendicular to and parallel to growth direction, photographed and measured. The measured primary and secondary arm spacings have been correlated to the changes in growth conditions, i.e. growth rate and temperature gradient.