Solidification behaviour of Sn droplets embedded in an icosahedral Al-Cu-Fe matrix

The solidification behaviour of Sn droplets embedded in an icosaheral quasicrystalline Al-Cu-Fe matrix has been studied by a combination of differential scanning calorimetry (DSC), X-ray diffractometry and transmission electron microscopy. The as-melt spun ribbon consists of mainly dendritic quasicrystalline phase with Sn particles distributed at the interdendritic region with some minor crystalline phase at the interdendritic region. A single phase icosahedral quasicrystalline matrix was obtained by the heat treatment for 15 min at 750°C. Faceted Sn particles distributed through the quasicrystalline matrix with an orientation relationship. (1 2 1)Sn is perpendicular to the fivefold axis of quasicrystal. Sn solidification exotherm consisted of two broad peaks: a small exotherm with onset temperature of about 204°C, and the second broad exotherm with 137°C, which is about 28 and 95°C below the Sn melting temperature, respectively. With increasing cooling rate in DSC, peak temperatures decreased and both the peak height and peak width increased. Contact angles calculated from the cooling rate dependences of peak temperature and peak height were about 26 and 52° for the high temperature and low temperature exotherms, respectively.