Synergistic Effect of Cu-Sn Microalloying and Aging Temperature on the Precipitation Hardening and Mechanical Properties of Al-Mg-Si Alloys

Abstract

Systematic exploration of the synergistic effects of Cu-Sn microalloying and aging temperature on the age-hardening behavior and mechanical performance of Al-Mg-Si alloys is presented. The combined addition of Cu and Sn significantly enhances peak hardness, refining the precipitates. When peak-aged at 180 °C, the Cu-Sn-modified Al-Mg-Si alloy achieves a maximum hardness of 138 HV and a yield strength (YS) of 314 MPa, showing a consistent enhancement between hardness and YS governed by precipitation strengthening. The alloy also obtains an ultimate tensile strength (UTS) of 389 MPa, representing increases of 39.6% in yield strength and 29.7% in UTS compared with the Al-Mg-Si base alloy at its peak aging condition of 160 °C. Cu and Sn additions promote the formation of uniformly distributed β″ hardening precipitates and facilitate the evolution of Mg-Si-Cu-Sn co-clusters, thereby accelerating the precipitation kinetics. Furthermore, the incorporation of Cu and Sn reduces the density of brittle Fe-rich intermetallic compounds, while it leads to a notable reduction in elongation. The aging temperature of 180 °C is identified as the optimal condition, as it balances the nucleation rate of precipitates and their resistance to coarsening during the aging process. This work demonstrates that the strategic coupling of Cu-Sn microalloying with optimized aging temperature offers an effective approach to enhance the age-hardening response and comprehensive mechanical properties of Al-Mg-Si alloys, providing valuable insights for the design and development of high-performance aluminum materials.

Graphical Abstract