Impact of Cu/Mg ratio on thermal stability of hot extrusion of Al-4.6 Pct Cu-Mg-Ag alloys

Chih Horng Chang, Sheng Long Lee, Tiz Yu Hsu, Jing Chie Lin

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11 Scopus citations


This work explores how the Cu/Mg ratio affects the thermal stability of the extrusion of Al-4.6 pct Cu-Mg-Ag alloys at aerodynamic heating temperatures of up to 155 °C for 1000 hours. The Cu/Mg ratio was modified by adding various amounts of elemental Mg. The alloy microstructures, which determine thermal stability, were analyzed with an optical microscope, an electrical conductivity meter, a differential scanning calorimeter (DSC), and a transmission electron microscope. Experimental results indicate that reducing the Cu/Mg ratio of the alloy by the further addition of Mg causes Ω to become the primary strengthening phase after aging treatment, increasing the hardness and the thermal stability, although the θ′ phase is suppressed. The S phase does not affect the thermal stability of the alloy, because it is present in only a low quantity. Results of this study also demonstrate that the hot-extruded low Cu/Mg alloy satisfies the requirement of the material thermal stability of commercial supersonic aerial applications.

Original languageEnglish
Pages (from-to)2832-2842
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume38 A
Issue number11
StatePublished - Nov 2007


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