Cold-Workability and Microstructure Change with β-Phase Stability in High-Strength Ti-Mn Binary Alloys

The effect of manganese content (Mn-content) on the beta phase (β-phase) stability, plastic deformability and mechanical behavior of titanium and (8–18 wt.%) manganese low-cost alloys were investigated. The alloys were produced by electric-arc melting under inert argon atmosphere. Microstructure change during cold rolling was evaluated through x-ray diffraction, scanning electron microscope, transmission electron microscope and electron backscatter diffraction in solution-treated and cold-deformed conditions. The β-phase was predominant in all the alloys under study in addition to very fine ω-phase precipitates, especially in the lower Mn-content alloys. Cold workability of the alloys was initially increased in the low Mn-content alloys and then decreased dramatically in the higher Mn-content alloys. The deformation mechanisms were a combination between dislocation slipping and twinning, with a predominance of twinning in the low Mn-content and slipping in the high Mn-content alloys. Tensile test results showed that an ultra-high-strength alloy of about 1950 MPa was obtained in the high Mn-content alloys after cold deformation.