Aluminum Base Alloys

The success of mechanically alloyed superalloys led to the development of dispersion-strengthened aluminum alloys. Table 4 lists the compositions of the mechanically alloyed dispersion-strengthened aluminum alloys. Because an aluminum oxide layer is always present either on the surface of the powder particles at the start of processing or during milling, its incorporation into the alloy contributes to significant improvements in the properties of the alloy. Further, since aluminum is a ductile metal, PCAs are added to assist in minimizing cold welding during processing. Aluminum carbides are formed during MA by the decomposition of the PCA. Both the oxide or carbide type dispersions are approximately 30 to 50 nm in size and stabilize the ultrafine grain size. This results in a 50% increase in strength, higher fracture toughness, and improved resistance to stress corrosion cracking and fatigue crack growth of the mechanically alloyed materials. IncoMAP alloy AL-9052 has a density 5% less than that of conventional age-hardenable aluminum alloy of comparable strengths such as 2024. With its combination of lightweight, high strength, and corrosion resistance, IncoMAP alloy AL-9052 is evaluated for aerospace applications where marine corrosion is also a factor.

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