Heat Treatment of Aluminium Foam Precursors: Effects on Foam Expansion and Final Cellular Structure

Aluminium foams produced by the powder metallurgical route present an initial –anisotropic– semisolid expansion that has a detrimental effect on the foamability and on the subsequent quality of the final cellular structure. The present work proposes a method oriented to modify the precursors’ microstructure and overcome this problem. It is based on the use of heat treatments below the solidus temperature, and has been tested in AlSi10 (0.8 wt.%TiH2) commercial precursors from Alulight Company (Austria). The experimental results obtained have demonstrated that the thermal treatment induces notable changes in the microstructure of the precursor material. Then, these changes produce a reduced and smoother semisolid expansion and improve the quality of the final cellular structure, in terms of higher pore circularity and less amount of defects.