Fresh insights into structure-function-integrated self-antibacterial Cu-containing Al alloys: giving Al alloys a new...

Contact infection by bacteria and viruses is a serious concern to human health. The increasing occurrence of public health problems has stimulated the urgent need for the development of antibacterial materials. Al alloys are the fastest-growing mass-produced material group, a prerequisite for the lightweight design of vehicles, food containers and storage, as well as civil-engineering structures. In this work, the structure-function-integrated concept was used to design and produce self-antibacterial Al-xCu (x = 2.8 and 5.7) alloys for the first time ever. The antibacterial tests indicated that Al-2.8Cu and Al-5.7Cu alloys provided a stable and efficient bacteriostatic rate against S. aureus and E. coli, which was 87% for Al-2.8Cu and 100% for Al-5.7Cu against S. aureus at 24 h, and 89% for Al-2.8Cu and 94% for Al-5.7Cu against E. coli at 24 h. The antibacterial effect was similar to the commonly-used antibacterial materials with a similar Cu content. Furthermore, the mechanical properties and corrosion resistance of Al-2.8Cu and Al-5.7Cu were comparable to those of the current commonly-used commercial casting Al-Cu alloys. Structural insights into the performance and biomedical function by Cu-rich precipitates provided understanding of the mechanisms of these structure-function-integrated self-antibacterial Cu-containing Al alloys: (i) the Cu-rich precipitates produced strengthening, and (ii) the immediate contact with Cu-rich precipitates and the Cu²⁺ caused a synergistic action in improving antibacterial activity. This work gives Al alloys a new function and inspires fresh insights into structure-function-integrated antibacterial Al alloys.