Effect of sintering temperature on compressive properties of porous aluminum produced by spark plasma sintering

Porous aluminum with a porosity of 78% and pore sizes of 850-1000 mu m was produced by the spacer method including spark plasma sintering (SPS) at various sintering temperatures of 773-853 K and the dissolution of space-holding sodium chloride particles. The effect of sintering temperature on the compressive properties of porous Al was investigated. The stress-strain curves for the specimens fabricated at 8 13 K and higher exhibited a plateau region with a nearly constant flow stress to a large strain of about 40%. However, the specimens fabricated at less than 813 K showed no plateau regions, although there were no significant differences in the characteristics of the pores by macroscopic observation between the porous At specimen fabricated at 843 K and that fabricated at 773 K. Microscopic observation revealed that there were large voids in the cell wall of the specimens fabricated at 773 K, showing that sintering was insufficient and the connection of At powder was poor. Furthermore, the fully-dense Al specimen fabricated at 793 K exhibited poor ductility in tension. Therefore, poor ductility in tension of cell walls may be responsible for the lack of plateau regions in the specimens fabricated at less than 813 K.