Microalloying of Sc, Ni, and Ce in an advanced Al-Zn-Mg-Cu alloy

Using transmission electron microscopy (TEM), scanning electron microscopy, X-ray diffraction (XRD), and optical microscopy, the effects of microalloying elements of Sc, Ni, and Ce on the microstructure of a new super-high-strength ingot metallurgy (IM)/Al-Zn-Mg-Cu alloy (C912) have been correlated with mechanical properties and stress corrosion cracking (SCC) behavior. Using microalloying with Sc, Ni, and Ce, the C912 alloy can exhibit very high strength and good SCC resistance. Compared to the baseline C912 alloy, Sc refines the microstructure and retards recrystallization, Ni promotes the development of matrix precipitates, which enhance the strength and SCC resistance, and Ce has little effect on alloy strengthening in the three microalloying additions studied. The Sc-containing alloy (C912S) is the most attractive and even exhibits higher strength (ultimate tensile strength (UTS) greather than 660MPa) than the new Alcoa aluminum alloy 7055 and the Russian alloy B96, which have the highest strengths of the commercial IM/Al-Zn-Mg-Cu alloys.