Customised heat treatment of TiH<inf>2</inf> for the foaming of aluminium alloys

The requirement for an alloy-specific heat treatment of TiH2 for producing foams by the powder metallurgy route was demonstrated in this study. Three heat-treated TiH2 powders were used to produce foams from three Al–Si–Mg alloys having different liquidus temperatures. Dehydrogenation behaviour of heat-treated TiH2 was studied using mass spectroscopy and thermogravimetry analysis. Foams were characterised by means of X-ray tomography. Quasi-static compression tests were employed to test their mechanical property. Using a combination of three alloys and three heat treatments, it was demonstrated that a good foam structure can be obtained when the maximum hydrogen release from TiH2 takes place after the complete melting of the alloy. The amount of hydrogen released during solid and semisolid stages of foaming also play a role in determining the final structure of the foams. It was also observed that such foams with a good structure possess a higher strength compared to the foams produced by using blowing agent that releases maximum hydrogen before complete melting.