Effect of TiH2 particle size distribution on aluminum foaming using the powder metallurgy method

TiH2 decomposes over a range of temperatures strongly influenced by diverse factors including particle size. In the present research, a systematic study of the dehydrogenation behavior of TiH2 powder of different particle size distribution was undertaken with the aid of thermogravimetric analysis. The effect of this parameter on aluminum foaming was evaluated. It was found that when TiH2 exceeds a critical particle size (around 50 μm), dehydrogenation occurs as a single desorption event with onset temperatures around 500 °C. The reduction of particle size, besides reducing the onset of hydrogen release, decreases the dehydrogenation rate. As a result, the first dehydrogenation event gets sharper and tends to overlap with the second with increasing particle size. The use of selected powders on foaming showed that the final foam expansion and porosity features, such as pore size, pore density, and homogeneity are largely influenced by the particle size distribution of the foaming powder. TiH2 of the largest particle size was the most suitable for foaming pure aluminum.