Enhancement of uniform elongation in high strength Ti–Mo based alloys by combination of deformation modes

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2011-05, Vol.528 (13), p.4569-4578
• Main Authors: Min, X.H., Tsuzaki, K., Emura, S., Tsuchiya, K.
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Combination of deformation modes; Cross-disciplinary physics: materials science; rheology; Deformation; Elasticity. Plasticity; Elongation; Equivalence; Exact sciences and technology; Fractures; Grains; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Other heat and thermomechanical treatments; Phase stability; Physics; Segregations; Slip; Treatment of materials and its effects on microstructure and properties; Twinning; Uniform elongation; Yield strength; β titanium alloys
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2011.02.071

► Combination of deformation modes is effective for the enhancement of uniform elongation. ► The alloys deformed by slip and twinning can be designed with the Mo equivalency. ► The deformation is heterogeneous among the grains and the twins are not seen in some of the grains. ► The segregation of alloying elements affects the heterogeneous deformation. A combination of different deformation modes, namely, dislocation slip and {3 3 2}〈1 1 3〉 twinning was found to be effective for achieving high yield strength and large uniform elongation in the β type Ti–15Mo–5Zr and Ti–10Mo–2Fe alloys in the as-solution treated condition, where the Mo equivalency was designed to be between 15.3 and 18.7 mass%. The high yield strength was caused mainly by the slip, and the large uniform elongation was caused by the twinning through significant work hardening. The change in the work hardening rate with strain correlated well with the formation of mechanical twins. The deformation was heterogeneous among the grains and the twins were not seen in some of the grains even after the tensile fracture. This heterogeneity was discussed based on the effects of the grain orientation and the segregation of alloying elements.