Structure and strength of powder metallurgy aluminum alloy AK-6

The interface chemical compositions and fine structure of sintered aluminum alloys were studied by the methods of Auger-electron spectroscopy and transmission electron microscopy. The transfer of impurity elements from the surface of powders to grain boundaries in the sintered alloys was experimentally confirmed. Enrichment of grain boundaries in oxygen, sulfur, and calcium causes brittle intergranular fracture, and seems to be the main reason for the lower strength of sintered alloys. Increased strength can be obtained by the elimination of intergranular brittleness, and the formation of dispersed precipitates of second phases in the matrix.