Effect of Sn on microstructure and properties of Ti–Zr–Nb–Sn medium-entropy alloys (MEAs)

Ti-rich body-centered cubic (BCC) high-entropy alloys (HEAs) and medium-entropy alloys (MEAs) are regarded as potential biomaterials due to their excellent biocompatibility, corrosion resistance, and comprehensive performance. In this study, three as-cast Ti–Zr–Nb–Sn MEAs (Ti 45 Zr 45 Nb 7 Sn 3 , Ti 45 Zr 45 Nb 5 Sn 5 , and Ti 45 Zr 45 Nb 3 Sn 7 ) were prepared and characterized in detail. Results show that all three MEAs presented a dendritic morphology with single BCC structure, and their elastic modulus was less than 60 GPa. The yield strength of Ti–Zr–Nb–Sn MEAs increased from 775 to 833 MPa due to the solid solution strengthening effect caused by Sn addition, but their tensile ductility decreased from 11 ± 0.5 to 8 ± 0.8%. The addition of Sn content lowered the corrosion resistance of Ti–Zr–Nb–Sn MEAs in phosphate buffer saline solution, and pitting corrosion occurred on the surface with the excessive addition of Sn element. These Ti–Zr–Nb–Sn MEAs with above-mentioned properties can provide references for the design of biomedical materials. Graphical abstract