Contribution of nano-sized lamellar microstructure on recoverable strain of Ti–24Nb–4Zr–7.9Sn titanium alloy

Intragranular nano-sized α phase with lamellar morphology was induced in the multifunctional Ti–24Nb–4Zr–7.9Sn (wt.%) alloy by short-time thermal treatment. This peculiar α + β dual microstructure resulted in a promising combination of mechanical properties including low modulus (47 GPa), high strength (850 MPa) and reasonable ductility (∼10%). This nano-sized network of lamellar alpha phase has been obtained by short-time ageing at 573 K on solution-treated (ST) samples and at 973 K on cold-rolled (CR) samples, respectively. Suppression of the stress-induced martensitic transformation, keeping the intrinsic modulus at a low level, has been clearly noticed advantageously in both cases. In the treated specimens, a stable strain recovery of about 2.7% was obtained until tensile fracture during cycling loading.