Novel Al-Cu-Mn-Zr-Sc Compositions Exhibiting Increased Mechanical Performance after a High-Temperature Thermal Exposure
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JMEPEG https://doi.org/10.1007/s11665-020-05040-0
Novel Al-Cu-Mn-Zr-Sc Compositions Exhibiting Increased Mechanical Performance after a High-Temperature Thermal Exposure Justin Lamb
, Baptiste Rouxel, Timothy Langan, and Thomas Dorin
(Submitted May 27, 2020; in revised form July 22, 2020) The presence of complex, core–shell Al3(Zr, Sc) dispersoids in Al-Cu alloys has recently been found to significantly refine h¢ precipitates resulting in increased mechanical properties. The purpose of this work was to take advantage of these effects to develop alloys with enhanced resistance to high-temperature thermal exposure compared to industrial baseline products. A series of Sc-bearing Al-Cu alloys were designed, manufactured using tailored homogenization practices and tested. It was found that a novel AlCu-Mn-Zr-Sc alloy exhibited higher tensile strength than AA2219-T8511 after a thermal exposure of 280 C—24 h. The presence of Sc-containing primary intermetallics was also observed in V-bearing compositions. Keywords
Al-Cu alloys, high-temperature thermal exposure, homogenization, mechanical properties, primary intermetallics, scandium
1. Introduction First discovered by Wilm (Ref 1) in 1911, the agehardenable 2xxx-series of aluminum alloys have long been utilized for aerospace applications, and more recently in other transportation industries, due to their high specific strength (Ref 2, 3). The alloysÕ strength arises from the various hardening precipitates that form in their microstructure which impede dislocation motion. However, when exposed to temperatures in excess of 200 C, these precipitates are prone to coarsen resulting in a significant strength loss. A large number of structural applications in the aerospace and automotive industries are subject to high-temperature thermal exposures, especially near engine components. Traditionally, this has led original equipment manufacturers (OEMs) to use heavier, more expensive alloys in lieu of aluminum for these applications. Hence, there is a strong need to improve the stability of precipitates in 2xxx-series aluminum alloys to increase their operating temperatures and aid OEMs in various light weighting initiatives. It is well known that the precipitation process in 2xxx-series alloys is dependent on both alloy composition and processing. For example, alloys with a high Cu/Mg ratio (e.g., AA2219) are prone to exhibit disk-shaped h-type precipitates, whereas the microstructures of alloys with a low Cu/Mg ratio (e.g., AA2024) are dominated by lath-shaped S-type precipitates. Justin Lamb, Universal Alloy Corporation, 180 Lamar-Haley Pkwy, Canton, GA 30114; Baptiste Rouxel and Thomas Dorin, Institute for Frontier Materials, Deakin University, Geelong, Australia; and Timothy Langan, CleanTeQ LTD, Notting Hill, Australia. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
Likewise, cold work prior to artificially aging is known to directly affect the precipitation process and aging kinetics of 2xxx-series alloys (Ref 4, 5). In ad
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