Simultaneously achieving exceptional and heat treatment insensitive strength-ductility synergy in an α plus β titanium alloy via tailoring silicide and heterogeneous α precipitates

The development of cost-effective titanium alloys with outstanding mechanical properties has always been a primary concern of the modern aerospace industry. However, the intrinsic sensitivity of their alpha precipitates to heat treatments proliferates the manufacturing costs to achieve desirable strength and ductility, especially in engineering occasions. In current work, a silicide-containing alpha+beta Ti-5Al-7.5V-0.5Mo-0.5Zr-0.5Si (TC5751S) alloy has been evidenced to exhibit advanced mechanical properties with reduced sensitivity to heat treatments. It is noted that more nano-scale secondary alpha (alpha s) precipitate with a simultaneous dissolution in micron-scale primary alpha (alpha p) and (Ti, Zr)5Si3 silicides in the current alloy as the solution temperature increases. However, this alloy shows excellent and stabilized strength-ductility synergy in all cases (ultimate tensile strength: 1335 +/- 30 MPa, yield strength: 1245 +/- 30 MPa, fracture strain: 9.6 % +/- 0.5 %) irrespective of the aforementioned variations in the microstructure. This stabilized strength and ductility of TC5751S are rationalized based on the compensation mechanisms between the contributions from silicide and heterogeneous alpha precipitates. The quantitative analysis unveils that the increased alpha s/ beta phase boundary strengthening (sigma PB) is approximately offset by the decrease in silicide strengthening (sigma silicide) due to silicide dissolution with increasing solution temperatures, leading to the strength of TC5751S in a dynamic equilibrium state. Simultaneously, the dissolution of silicides reduces the cracking tendency and complements the ductility loss due to alpha p reduction and alpha s precipitation, leading to the ductility insensitive to heat treatments. Therefore, the compensating role of silicides to the effects of heterogeneous alpha precipitates on both the strength and ductility of titanium alloys has been well-verified in our work, providing a novel pathway to the development of high-performance titanium alloys friendly to processing strategies. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.