Microstructure evolution and multi-reinforcement mechanisms in Al-Cu-Ag alloys

Abstract

As one of the most commonly used binary alloys, the effect of intermetallic compounds (IMCs) of Al-Cu alloys in powder metallurgy on their structure and properties is instructive for tailoring Al-Cu alloys for different applications. In this investigation, a series of Al-Cu-Ag alloys with varying Cu compositions were fabricated via hot pressing. TEM analysis identified CuAl2 as the primary intermetallic compounds, with Ag existing in forms including Ag2Al, elemental Ag, and an Ag-(Cu) solid solution. The modulation of Cu content influenced the state of Ag and the mechanical behaviors of the Al-Cu-Ag alloy. Particularly, the high Al/Cu alloy, benefiting from a synergistic effect comprising stacking faults, nanoscale precipitates, and solid solutions, exhibited outstanding mechanical properties. Conversely, the Al-50Cu-3Ag alloys displayed significant brittleness, attributed to the adverse impact of large-scale intermetallic compounds and increased grain size due to the formation of CuAl2. The incorporation of nanoparticles effectively mitigated the grain size in high Al/Cu alloys. This study elucidates the correlation between the evolution of intermetallic compounds and composition in Al-Cu alloys, offering novel insights into the reinforcement of both Al-based and Cu-based alloys.