Effect of Ti on the microstructure and wear behavior of a selective laser melted Al-Cu-Mg-Si alloy

The elimination of hot cracking and enhancement of wear resistance have important practical significance for wide application of high-strength Al–Cu–Mg–Si series aluminum alloys fabricated by selective laser melting (SLM). In the present work, Ti was introduced to refine the microstructure of the selective laser melted Al–Cu–Mg–Si alloy, whose effect on the densification, microstructure evolution and wear resistance was explored in detail. After adding 0.6 wt % Ti, the microstructure transformed from coarse columnar grains to a fine duplex microstructure consisting of equiaxed and columnar grains, while microhardness of the SLM processed Al–Cu–Mg–Si alloy was increased from 148.9 ± 1.5 HV to 159.3 ± 1.7 HV, respectively. The wear behavior was evaluated on a ball-on-flat tribometer by sliding against 100Cr6 steel at room temperature. With the addition of Ti, the wear rate of SLM processed Al–Cu–Mg–Si was decreased by 49.6% for the applied load of 10 N. The refined heterogeneous microstructure helps to achieve strength-ductility synergy of the Al–Cu–Mg–Si–Ti alloy, which provides superior resistance to indentation behavior and initiation of cracks. The wear mechanism of the Al–Cu–Mg–Si alloy under the applied load of 10 N is abrasive wear and delamination wear, which for the Al–Cu–Mg–Si–Ti alloy is abrasive wear with slight delamination wear.