Fig. 4 shows the quasi-static compressive stress-strain curves of foams containing either raw or rounded EP particles. All of the graphs exhibit the well-known compressive response of metallic foams which comprises three distinct regions; the elastic region in which the stress increases sharply, the plateau region which shows a gradual increase in stress over a prolonged strain range, and the onset of densification where the stress increases sharply again. The foams with even slightly higher density exhibit higher stresses. The density of foams may vary due to uneven shape of particles that affects the particles packing density. A previous study showed that the mechanical properties of EP/aluminium syntactic foam is controlled by the matrix and EP particles do not have a direct effect on the mechanical properties [20].