Helwig, H.-M.; Garcia-Moreno, F.; Banhart, J.: A study of Mg and Cu additions on the foaming behaviour of Al-Si alloys. Journal of Materials Science 46 (2011), p. 5227-5236
10.1007/s10853-011-5460-5

Abstract:
Aluminium casting alloys containing Mg and Cu in addition to Si were investigated with respect to their potential to be foamed. The kinetics of foam expansion of different alloys was studied and the resulting structures were characterized. Of the stages of evolution of foams, namely pore nucleation, foam growth in the semisolid state, further expansion in the fully liquid state, the latter two were explored. Expansion in the semisolid state could be related to the available liquid fraction. Mg- containing Al-Si alloys yielded a less coarse and more uniform pore structure than the other alloys investigated. However, achieving a high volume expansion required restriction to a narrow process window and led to the suggestion of AlMgSi8 as a practical alloy.