Effect of high silicon content in enhancing the creep properties of a PM near-α Ti–6Al–2Sn–4Zr–2Mo–0.5Y–0.5Si alloy

This study investigates the effect of high Si content on the creep properties and deformation mechanisms of a powder metallurgy (PM) near-α titanium alloy with a composition of Ti–6Al–2Sn–4Zr–2Mo–0.5Y–0.5Si (wt.%) fabricated using high-energy ball milling (HEBM) and thermomechanical powder consolidation (TMC). Under 600 °C/250 MPa, the alloy exhibits a 263 % increase in creep life, a 48 % reduction in steady-state creep rate, and 100 % improvement in creep fracture strain compared with the corresponding titanium alloy containing 0.1 wt% Si under the same fabrication and heat treatment conditions. The superior creep properties are attributed to the stabilized α/β and α/β t interfaces, the uniform dispersion of (Ti, Zr) 6 Si 3 nanoparticles, and the increased Si solubility in both α and β phases, all of which collectively hinder dislocation movement. Additionally, Si addition suppresses the formation of continuous α GB plates, while the presence of higher Si solubility and dispersed nanoscale silicides alleviates stress concentration, delays void and microcrack formation, and ultimately enhances creep fracture strain. These findings underscore the critical role of interface stability, nanoscale silicide dispersion, and enhancing Si solubility in optimizing high-temperature titanium alloys for extreme service environments.