Structural Features and Mechanical Behavior of Pseudo-β-Ti–Mo–Sn Alloys As-Quenched and As-Aged for Biomedical Application

The paper considers in detail the structural and deformation behavior of ternary metastable β-Ti–(10,12,14)Mo–(1 ÷ 8)Sn (wt.%) alloys under uniaxial tension depending on the concentration of doping elements (Mo and Sn) and heat treatment (quenching and aging). Low-temperature aging allows a significant increase in strength up to 1.5 ÷ 2 times while preserving ductility. The optimal combination of mechanical properties: high values of yield strength σY = 680 MPa and ultimate tensile strength σUT = 1125 MPa along with high ductility of 43% has been achieved in Ti–12Mo–4Sn alloy (wt.%) after aging at 473 K for 60 s. A high strength of the alloys, accompanied by a high rate of strain hardening, without loss of ductility, is a result of the complex nature of deformation with a predominance of TRIP/TWIP mechanisms, i.e. the simultaneous processes of induction of strain martensite and twinning. Record values of strain hardening are reached for Ti–10Mo–(2 ÷ 6)Sn (wt.%) alloys, where the predominant deformation mechanism according to powder XRD and metallography is the TRIP effect, which significantly exceeds the TWIP effect, prevailing in alloys with higher Mo and Sn contents. The mechanical properties of these alloys (high strength and ductility) make them potentially suitable for commercial biomedical applications.