Pii: S1359-6462(00)00548-0

Al foams have found increasing applications in a wide range of structural and functional products, due to their exceptional mechanical, thermal, acoustic, electrical and chemical properties [1–3]. Al foam structures have densities only fractions of that of a solid structure and therefore have high specific strength and stiffness. They also have excellent properties for impact energy, vibration and sound absorption. Examples of their applications include lightweight panels for building and transport against buckling and impact, non-flammable ceiling and wall panels for thermal and sound insulation. Open cell foams can also be used as heat exchangers, filters and catalyst carriers. The applications of Al foams on a large scale are likely to be in the automotive industry with an aim to improve the vehicle crashworthiness and thus passenger safety. There currently exist a wide range of manufacturing methods [1–3], which can generally be grouped into five categories according to the forms of the precursory Al and the types of the pore-forming agents, namely melt-gas injection, melt-foaming agent, powder-foaming agent, investment casting and melt infiltration. However, the Al foams produced by these methods are either too expensive due to the high production costs or too poor in quality due to poor controllability in pore structure and porosity. As a consequence, the commercial applications of Al foam components are still limited. With a rapidly increasing demand for high quality Al foams, there has been a growing need for developing cost effective manufacture technologies. This paper describes a new sintering-dissolution process (SDP) for manufacturing net-shape, open-cell Al foams, characterises the porosity, microstructure and compressive properties of the foams produced under a range of SDP conditions, and discusses the capabilities of SDP.