Bubble Nucleation of PM Al-9Si Foam

Being the first step of foaming, bubble heterogeneous nucleation of aluminum foam has remarkable effects on the final cell structure of aluminum foam. The bubble heterogeneous nucleation of foaming Al-9Si and T i H 2 powder compact has been analyzed. The results obtained are given as follows: (1)The remaining T i H 2 particles act as the nuclei during heterogeneous nucleation. (2)The nucleation rate increases with the increasing of T i H 2 content, the decrease of T i H 2 granularity, the elevation of foaming temperature, and the elongation of foaming time. (3) Only about 5‰ bubble nuclei can survive and develop to the final foam cells. (4)The influence of processing parameters on the nucleation rate descends by the following sequence: foaming temperature elevates 20°C, T i H 2 granularity decreases from 150μm to 26μm, T i H 2 content increases 0.5%wt., and the time for foaming extends 10s.