Alloys in the Ti–Si–Sn System (Titanium Corner): Phase Equilibria, Structure, and MechanicaL Properties

Abstract

The joint effect of Si (5, 7, and 10 at.%) and Sn (3–15 at.%) on the structure and mechanical properties of cast Ti-rich Ti–Si–Sn alloys is studied. Hypoeutectic alloys with 10 at.% Si are shown to possess the highest level of properties due to the greater volume fraction of eutectic (β*) + Ti₅Si₃. It is shown that the dependence of strength and hardness of Ti–Si–Sn alloys versus Sn content is nonmonotonic. The properties improve with increasing tin content to 7–10 at.% due to the solid-solution hardening mechanism. The elastic modulus and plasticity of all the alloys decrease with increasing Sn concentration. The elastic modulus for the alloys with 7–15 at.% Sn almost halves, decreases to 65–60 GPa. The level of long-term hot hardness of the alloys at different temperatures depends on Si and Sn content. In general, tin additions increase heat resistance of all the alloys studied. The deviation from the dependence for individual alloys results from variation in their phase composition. The mechanical behavior of Ti-rich Ti–Si–Sn alloys versus Sn concentration is due to the formation of intermetallic Ti₃Sn phase.