Structure and precipitation hardening response in a cast and wrought Al-Cu-Sn alloy

Abstract Experimental studies including microhardness and electrical conductivity measurements, transmission electron microscopy (TEM) together with atom probe tomography (APT) have been carried out for exploring the influence of tin (Sn) trace addition on the structure and precipitation hardening response in Al-Cu based alloy after either casting or cold or hot rolling. It is shown that the Sn trace addition refines the Al2Cu phase in an as-cast Al3.5Cu0.1Sn (wt.%) alloy. The alloy showed an increase by about 20% the peak hardness (~120 HV) for both cast and wrought products as well as significant reduction in the aging time to peak hardness (from 12 h to 2 h at 175 °C). According to the TEM and APT, the increased hardness is due to the formation of much finer θ′-phase precipitates with high number density.