Influence of powder pre treatments on metal foam pore structure

Aluminium foams were produced via the powder route in which blends of metal powders and blowing agent are first compacted and then melted. AlSi6Cu4 casting alloy was foamed using titanium hydride as blowing agent. The blowing agent was subjected to various oxidising pre treatments in air prior to compaction. The decomposition behaviour of the pre treated blowing agent was characterised by thermo analysis. The effect of pre treatment on foaming was described with tomographic imaging of foams in early stages of expansion, i.e. 60 porosity. We find a beneficial effect of pre treatment on foam morphology and explain it with the effect of oxide films generated on the surface of the blowing agent particles