A novel (CuMnNi) 100-x Sn x medium entropy bronze alloys with excellent mechanical properties and wear resistance

Cu-Mn-Ni-based medium -entropy bronze (MEB) alloys exhibit attractive compressive strength and ductility, making them highly promising for structural applications in comparison to conventional copper alloys. Here, a series of (CuMnNi) 100-x Sn x (x = 0, 5, 10, 15, and 20, mass ratio) MEB alloys were fabricated using the induction melting technique, and the effects of Sn content on the phase formation, microstructure evolution, and mechanical properties were extensively studied. Additionally, the tribological properties of the MEB alloys were investigated and compared with the conventional aluminum bronze C6161 alloy. The results indicate that adding Sn element promotes the formation of body -centred cubic (BCC) phase in the MEB alloys and causes a distinct microstructure transition from the single face -centered cubic (FCC) phase to the duplex phase structure consisting of FCC and BCC. Benefiting from the solid solution strengthening induced by Sn atoms and the formation of hard BCC phase, the MEB alloys exhibit significantly enhanced hardness, yield strength, and compressive strength as the Sn content increases from 0 to 20 wt%. The wear resistance of the MEB alloys improves with increasing Sn content, surpassing that of the C6161 alloy when x exceeds 5. The competitive mechanical and tribological properties of the MEB alloys are primarily attributed to the synergistic effect between the ductile FCC phase and the hard BCC phase.