Effect of Sn addition on mechanical, wear, and electrochemical properties of Ti-Al-Sn alloys

Abstract

This study aims to investigate the effect of Sn content on the structural, mechanical, wear, and electrochemical properties of Ti-6Al-xSn (x = 3.5–17.5, wt%) alloys fabricated by powder metallurgy method. The results showed that the microhardness generally decreased with increasing Sn content, although there was an unusual increase in microhardness in the alloy with 10.5 wt% Sn. Depending on the Sn content, various phases such as α-Ti, Ti₃Sn, and Ti₃Al indicated complex phase formations. The flexural and tensile strengths increased up to 10.5 wt% Sn content, but the strengths reduced above this level. The maximum values for flexural and tensile strengths were obtained as 270 MPa and 125.8 MPa, respectively. With increasing Sn content, the fracture surfaces shifted from cleavage mode to mixed brittle and ductile failure modes. The wear tests were conducted in two different environments: dry and wet conditions. Considering dry sliding conditions, the lowest specific wear rate was obtained as 0.85 × 10⁻⁶ mm³/N·m in the alloy coded 3.5Sn at a sliding distance of 1500 m. On the other hand, the highest wear was measured as 2.89 × 10⁻⁶ mm³/N·m in the 17.5Sn coded sample at a sliding distance of 6000 m in wet conditions. The wear results demonstrated a relationship between mechanical properties and wear resistance, which was influenced by the existence of porosity. The Ti-6Al-7Sn alloy exhibited the best corrosion resistance with a 2.22 × 10⁻⁷ i_corr value, while the one with Ti-6Al-17.5Sn alloy showed the worst performance with a 9.71 × 10⁻⁶ i_corr value.