Directional solidification of aluminium–copper alloys

Directional solidification experiments have been carried out on different Al–Cu alloys as a function of solidification parameters, temperature gradient G, growth rate V, and composition C0. The specimens were solidified under steady state conditions with a constant temperature gradient (7.4 K mm−1) at a wide range of growth rates (9–490 μm s−1) and with a constant growth rate of 9.5 μm s−1 at a wide range of temperature gradients (1.0–7.4 K mm−1). Microstructural parameters, the primary dendrite arm spacing λ1, secondary dendrite arm spacing λ2, dendrite tip radius R, mushy zone depth d were measured and expressed as functions of solidification parameters, G, V and C0 by using a linear regression analysis. The results were in good agreement with previous experimental work and current theoretical models suggested for dendritic growth.