A novel Co-free high-entropy alloy with excellent antimicrobial and mechanical properties

Microbiologically influenced corrosion and bacterial infection lead to serious losses to human production and life. Developing alloys with inherent antibacterial properties is a vital way to solve the above issues. However, the widely used Cu-containing stainless steels show insufficient antimicrobial properties and relatively low yield strengths, which further limit their application in extreme service environments. Based on the design concept of high-entropy alloys (HEAs), a novel low-cost Co-free CrFeNi_0.5Cu_0.3 HEA with an optimal combination of antibacterial and mechanical properties was designed and prepared. This alloy comprises triple-phase structures, including FeNi-rich face-centered cubic (FCC1), Cu-rich FCC2 and FeCr-rich body-centered cubic (BCC). The antibacterial rate of this HEA is up to 99.99% against Escherichia coli, which is far superior to that of classic 304 Cu-bearing stainless steel (304-Cu SS) and the most reported antibacterial alloys. In addition, the HEA exhibits excellent mechanical properties with a tensile strength of 1032 MPa and yield strength of 842 MPa, far surpassing the corresponding values of 304-Cu SS (i.e., 528 MPa and 210 MPa, respectively). These findings provide new insights for the development of low-cost and high-performance antibacterial alloys.