New Process-Microstructure Method for Affordable 2024 Series Aerospace Aluminum Alloys
New affordable 2024 series aerospace aluminum alloy has been developed. Fracture toughness has been demonstrated increase in inverse proportion to the root of the distance between constituents, Cu2FeAl7, formed during ingot solidification. Higher fracture toughness material is obtained by means of combination of reduction of Fe content and wider spacing between the constituents. The fractured surface of those materials has been confirmed to show larger dimples due to the wider constituents. An outcome is the fracture toughness increases 20% through broadening the space from 75 to 140μm. Fatigue crack growth (FCG) has been governed by the morphology of dispersoids such as Cu2MnAl20, Cr2Mg3Al18 and ZrAl3, formed in homogenization process during heat treatment of ingot. In a low ΔK region, the FCG rate is slower when Cu2MnAl20 becomes larger. It is reconfirmed that the FCG rate is still faster for small dispersoids, Cr2Mg3Al18 or ZrAl3 bearing materials than Cu2MnAl20 bearing one through bridging effect of dispersoids. In a high ΔK region, on the other hands, the FCG rate becomes slower by broadening the spacing of the constituents. A new 2024 series alloy (2x24) with high fracture toughness and excellent FCG resistance has been developed on the basis of process- microstructure-structure methods.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
T. Eto and M. Nakai, "New Process-Microstructure Method for Affordable 2024 Series Aerospace Aluminum Alloys", Materials Science Forum, Vols. 539-543, pp. 3643-3648, 2007