Tensile testing and cyclic tensile loading measurements were performed on heat-treated samples of annealed Ti-2448
and cold-rolled Ti-2448. Quenching from above the β-transus produces an alloy that is highly superelastic, has ultra-low
elastic modulus (10−25 GPa) and exhibits hysteresis on loading-unloading cycles. On repeated cycling the strain energy
absorbed in each cycle decreases. Annealed Ti-2448 exhibits a stable hysteresis loop. Peaks from the α
00 phase are
observed in X-ray diffraction (XRD) patterns, thus the material is quite lean in β-stabilising additions. The alloy is
shown to be highly unstable when heat-treated. A combination of small angle X-ray scattering (SAXS), transmission
electron microscopy (TEM) and X-ray diffraction (XRD) was employed to relate the thermally induced microstructural
evolution to the change in mechanical properties. A heat-treatment of 80 ◦C to the cold-rolled material precipitated the
ω phase, causing embrittlement. Increasing the ageing temperature from 80 to 300 ◦C increased the stiffness, made the
elastic regime more linear, and further embrittled the alloy. The low temperature heat-treatments precipitate both ω
and α
00 phases. A higher temperature ageing treatment at 450 ◦C increased the yield strength to over 1GPa and caused
embrittlement, indicating co-precipitation of α and ω phases.