Effects of Cd addition on the aging behaviors of Al-Cu-Mn-Ti-Zr alloy

摘要

Effects of Cd addition on the aging characteristicsof Al-Cu-Mn-Ti-Zr alloy were investigated using scanningelectron microscopy (SEM) and transmission electronmicroscopy(TEM). The air-melted Al-Cu-Mn-Ti-Zr alloy ingotswith and without Cd were solution treated at 543℃ for 13 hours,followed by water quenching. Aging treatments were carried out at170℃ up to 24 hours. In case of Cd-containing alloys, theaccelerated age-hardening makes the peak hardness higher than thatof Cd-free alloys. It is due to the fact that Cd atoms stimulate θ(CuAl2) precipitates and increase the density of θ'precipitates by forming Cd-clusters, which are knownto act as heterogeneous nucleation sites of θ'precipitation. With increasing Cd contents up to 0.2%,peak hardness and tensile strength were increased. Butbeyond 0.2% Cd contents, peak hardness and tensilestrength were deteriorated because of localizedsegregation of Cd atoms. The elongation was maintainedup to 0.15% Cd contents, but decreased rapidly beyond0.15% Cd contents. Therefore, it can be inferred thatthe optimum contents of Cd in Al-Cu-Mn-Ti-Zr alloy is about 0.15%.