The Effect of IMCs and Segregation on the Microstructure and Mechanical Properties of β-Type Titanium Alloys

Abstract

Two new β-type titanium (β-Ti) alloys of Ti-10.5Cr-5.4Mn-2.4Zr-0.9Al and Ti-15.6Cr-12Mn-3.3Zr were designed with the same bond order value 2.79 and different d-orbital energy level values of 2.28 and 2.16, respectively. The effect of intermetallic compounds (IMCs) and the segregation behaviors of β-Ti alloys were discussed by adding excessive and normal alloying elements to alloys under both as-cast and solution-treated conditions. The mono-β phase in the Ti-10.5Cr-5.4Mn-2.4Zr-0.9Al alloy and β+intermetallic compounds (IMCs) in the Ti-15.6Cr-12Mn-3.3Zr alloy were identified and observed. The as-cast and solution-treated alloys showed their ultimate tensile strength and fracture strain; these were 982 and 1002 MPa, with 9.82 and 9.89% for Ti-10.5Cr-5.4Mn-2.4Zr-0.9Al, and 448 and 296 MPa, with 0.12 and 0.11% for Ti-15.6Cr-12Mn-3.3Zr, respectively. Moreover, the Vickers hardness values of the as-cast and solution-treated alloys were 345 and 355 for Ti-10.5Cr-5.4Mn-2.4Zr-0.9Al, and 422 and 466 for Ti-15.6Cr-12Mn-3.3Zr, respectively.