Design of α-type Titanium Alloys with Improved Corrosion Resistance and Tensile Properties

Abstract:

Newly designed α-type titanium (α-Ti) alloys were proposed based on both electron parameters (bonding time Bo_t and d-orbital energy level Md_t). The newly designed α-Ti alloy Ti-5Al-4Zr-3.6Sn, modified alloy Ti-5Al-3Sn-1.9Zr, and reference alloy Ti-5Al-2.5Sn have the same Bo_t value of 3.847 and different Md_t values of 2.430, 2.426, and 2.422, respectively. The ultimate tensile strength (σ_UTS), fracture strain (?_f), and hot salt corrosion resistance of the three α-Ti alloys were measured. The three α-Ti alloys were produced by the cold crucible levitation melting (CCLM) technique. Results show that homogeneous microstructures can be observed in three α-Ti alloys. The α mono-phase in three α-Ti alloys has the grain size of approximately 600 μm. σ_UTS and ?_f of Ti-5Al-4Zr-3.6Sn alloy are 801 MPa and 16%, respectively; σ_UTS and ?_f of Ti-5Al-3Sn-1.9Zr alloy are 708 MPa and 15%, respectively; σ_UTS and ?_f of Ti-5Al-2.5Sn alloy are 603 MPa and 15%, respectively. After hot salt corrosion tests were conducted for 28.8 ks, the mass loss ratio of Ti-5Al-4Zr-3.6Sn, Ti-5Al-3Sn-1.9Zr, and Ti-5Al-2.5Sn alloys is 2.61%, 2.83%, and 3.10%, respectively. The results of σ_UTS, ?_f, and hot salt corrosion resistance indicate that the newly designed alloy Ti-5Al-4Zr-3.6Sn has great potential for practical applications.

Key words:alloy design;α-type titanium alloys;CCLM;tensile properties;hot salt corrosion test