Fabrication of porous magnesium with directional pores through use of hydrogen thermally decomposed from MgH₂ powders during unidirectional solidification

Porous magnesium with directional cylindrical pores (or “lotus-type” porous magnesium) was fabricated through the use of hydrogen decomposed from MgH₂ powders during unidirectional solidification. Liquid magnesium was cast into a mold in which MgH₂ powders were placed and was unidirectionally solidified, which achieved growth of pores elongated along the direction of solidification. The effect of the amount of the MgH₂ powders on the pore structure (porosity, diameter, and number density of pores) and the change in the pore structure along the pore growth direction were clarified. The porosity and number density of pores increase with increasing amount of MgH₂ powder, and the average diameter of pores decreases with increasing amount of MgH₂ powder. The pore structure changes with the growth of pores along the solidification direction.