Interflake spacings and undercoolings in Al–Si irregular eutectic alloy

Aluminium–silicon irregular eutectic alloy was melted in a graphite crucible in vacuum. This alloy was directionally solidified at a constant growth rate, V (8.3 μm/s) and at different temperature gradients, G (2.0–7.8 K/mm) and also with a constant G (7.8 K/mm) and different V (8.3–498.7 μm/s) in the Bridgman type directional solidification furnace. The interflake spacings, λi, were measured from both transverse and longitudinal sections of the specimens. The relationships between interflake spacings, λi and solidification parameters V and G were obtained by linear regression analysis method. The variations of interflake spacings, λi with V, G and undercoolings, ΔTi, were investigated and the relationships between them were examined. Operating parameters φ and η which reflect the spacing adjustment mechanism were obtained. λi2V, λi ΔTi, ΔTiV−a, λi3G and ΔTiG−b values were determined by using λi, V, G and ΔTi, values. The results obtained in this work have been compared with the eutectic theory and previous experimental results.