รูป 7 and ตาราง1 show the microstructure and density of the obtained sinters. As shown, the sinters' density is similar for specified chemical compositions and is not depending on the heating power. However, the effect of aluminum content on the density clearly visible. With the increase of aluminum content from 30% to 50% density of manufactured sinters increased from 90% to 97% accordingly. This effect is probably due to the large surface area of iron powder. Increasing the amount of aluminum, improves filling of the irregularities on the surface of the iron particles, and finally decrease the sinters porosity. Microstructures of all sinters shown in รูปที่7 are very similar.