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

作者：Calvo Dahlborg M^*; Popel P S; Kramer M J; Besser M; Morris J R; Dahlborg U

来源：Journal of Alloys and Compounds, 2013, 550: 9-22.

DOI：10.1016/j.jallcom.2012.09.086

• Microstructure
• SANS
• Melt
• Liquid
• Al-Si
• Superheat

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 %26quot;particles%26apos;%26apos; sizes. The results show that %26quot;particles%26apos;%26apos; 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 %26quot;particles%26apos;%26apos; 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 %26quot;particles%26apos;%26apos; 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.

• 出版日期2013-2-15