Investigating the Influence of Mg Content Variations on Microstructures, Heat-Treatment, and Mechanical Properties of Al-Cu-Mg Alloys

Abstract

The objective of this study was to examine the impact of varying magnesium levels in the α-Al + S + T region of the Al-Cu-Mg ternary phase diagram on the solidification process, microstructure development, tensile properties, and precipitation hardening of Al-Cu-Mg-Ti alloys. The outcomes indicate that alloys with 3% and 5% Mg solidified with the formation of binary eutectic α-Al-Al2CuMg (S) phases, whereas in the alloy with 7% Mg, the solidification process ended with the formation of eutectic α-Al-Mg32(Al, Cu)49 (T) phases. Additionally, a significant number of T precipitates were noticed inside the granular α-Al grains in all alloys. In the as-cast condition, the 5% Mg-added alloy showed the best combination of yield strength (153 MPa) and elongation (2.5%). Upon T6 heat treatment, both tensile strength and elongation increased. The 7% Mg-added alloy had the best results, with a yield strength of 193 MPa and an elongation of 3.4%. DSC analysis revealed that the increased tensile strength observed after the aging treatment was associated with the formation of solute clusters and S″/S′ phases.

Improvement in Mechanical Properties of Al2024 Alloy Using Mechanical Working and Heat Treatment

“…It was previously noted [ 29 , 30 , 31 , 32 , 33 ] that the dispersoids could strengthen the alloy through the Orowan mechanism. Due to being incoherent with the Al matrix, the interface between dispersoids and the Al matrix had high energy and provided a preferential nucleation position for the S phases [ 4 , 8 , 34 , 35 , 36 ]. Furthermore, the particles themselves could hinder dislocation movement and pinned grain boundary migration and thus impede grain growth [ 24 , 32 , 37 , 38 ].…”

“…The Al2024 is a typical Al-Cu-Mg-series light-weight structural material and has extensive applications in aerospace, automobile manufacturing, and other fields due to its low density, high specific strength, high specific modulus, good processing performance, heat-treatability, etc. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. With the development of modern industry, higher requirements for the comprehensive mechanical properties of Al alloys have been proposed.…”