Powder metallurgical processing of a 2xxx series aluminum powder metallurgy metal alloy reinforced with AlN particulate additions

Two AlN powders were admixed with a commercially-relevant press-and-sinter aluminum alloy, differentiated by their mean particle sizes of 3.0 and 12 mu m. The effects on powder characteristics and mechanical properties were of primary interest and were compared to nonreinforced compacts. Ceramic additions affected the behavior of the alloy in the powdered, green and sintered state. AlN additions promoted gains in green strength but negatively affected sinterability in some instances although effects were marginal when coarse or fine AlN powder additions were limited to 5 vol% and 2 vol%, respectively. Decreased densities manifested as marginal decreases in yield strength, UTS and fatigue properties. For a fixed AlN concentration, alloys containing D-50 = 12 mu m or D-50 = 3 mu m AlN exhibited comparable mechanical properties. Above 5%, the coarser particulate maintained a higher sinterability and superior mechanical properties. Dynamic elastic modulus measurements of 73.0 and 74.3 GPa were measured for compacts with 2 and 5 vol% of coarse AlN particulate. AlN additions did not significantly influence the fatigue survival stress.