Superheat-dependent microstructure of molten Al-Si alloys of different compositions studied by small angle neutron scattering

TitleSuperheat-dependent microstructure of molten Al-Si alloys of different compositions studied by small angle neutron scattering
Publication TypeJournal Article
Year of Publication2013
AuthorsCalvo-Dahlborg M, Popel PS, Kramer MJ, Besser M, Morris JR, Dahlborg U
Journal TitleJournal of Alloys and Compounds
Volume550
Pages9-22
Date Published02
Type of ArticleArticle
ISBN Number0925-8388
Accession NumberWOS:000312149700002
Keywordsal-si, aluminum-alloys, crystallization behavior, ELECTRICAL-RESISTIVITY, HEAT-TREATMENT, liquid, liquid structure, magnetic-properties, mechanical-properties, melt, melt superheat, metallic glasses, microstructure, pulse modification i, SANS, Superheat
Abstract

The microstructure of Al-Si alloys of hyper- (Al80Si20) hypo- (Al93Si7) and eutectic (Al87.8Si12.2) compositions have been investigated by Small Angle Neutron Scattering (SANS) during thermal cycles above liquidus temperature. Among the three investigated compositions, the eutectic one is the most homogeneous at first heating temperature, containing in the largest amounts three families of "particles'' sizes. The results show that "particles'' of different sizes exist in Al-Si melts of different compositions and that their distribution change during thermal cycles above the melting point. The microstructures can be well explained by the dissolution and branching temperatures extrapolated from density measurements. During heating up to maximum temperature large "particles'' dissolve and recombine into smaller ones. For all compositions, the melt at the maximum temperature after heating is more homogeneous. There exist a temperature T-d at which "particles'' dissolve above melting and another temperature T-b at which a molten alloy can be considered as fully homogeneous, i.e. in a true equilibrium solution state. The presented results give the background for a complete understanding of the morphology and the physical properties of Al-Si alloys of different compositions and synthesized under different conditions. (C) 2012 Elsevier B.V. All rights reserved.

URL<Go to ISI>://WOS:000312149700002
DOI10.1016/j.jallcom.2012.09.086
Alternate JournalJ. Alloy. Compd.