Effect of Cu on Pore Structure of Al–Si Foam

The alloy composition is an important factor effecting the pore structure of aluminum foam. In this paper, the powder compact foaming method was used, and different content of Cu element powders were added to the alloy Al–9Si, for investigating the effect of alloying element on foaming process. With the Cu content of Al–Si–Cu alloy increasing, the expansion ratio is increased, the time required to reach maximum expansion is shortened, and the number of fissure-like pores at early foaming stage is decreased. This improving action is related to the higher volume fraction of liquid phase in same melting temperature caused by increasing Cu content in alloy. Comparing different Al–Si–Cu alloys with different Cu content at same expansion ratio, the higher Cu content, the smaller pore size and the thinner cell wall. This beneficial effect on pore structure is attributed to the addition of Cu that is benefit to increasing the viscosity of Al–Si–Cu alloy during foaming. And at same expansion rate, the more content of Cu in Al–Si–Cu alloy, the higher compressive strength of aluminum foam. Graphic Abstract