Microstructure characterization and tensile performance of a high-strength titanium alloy with in-situ precipitates of Ti5Si3

Abstract

Near β titanium alloys with excellent properties are increasingly preferred for aerospace structural applications, among which the alloys with in-situ precipitated silicides are especially intriguing. Here in this work, based on the low-density, high strength and comparable thermal expansion coefficient to titanium of Ti5Si3, a novel high-strength titanium alloy with in-situ Ti5Si3 precipitate has been developed and further heat treated to regulate the microstructure and properties. The results revealed that the in-situ precipitates including both the needle-shaped secondary α-Ti in the β-Ti matrix and the spherical Ti5Si3 in proximity of α/β phase boundaries contributed to the superior strength and ductility for the alloy after the optimal heat treatment at 800 °C for 40 min. Specifically, it exhibited an ultimate strength of 944.1 MPa and an elongation value of 12.5% with excellent work hardening behavior and ductile fractography including abundant tear edges and dimples. This work validated the strategy of introducing in-situ titanium silicides to stabilize the microstructure and enhance work hardening for developing novel titanium alloys with adjustable and superior properties.