Exceptionally high strain-hardening and ductility due to transformation induced plasticity effect in Ti-rich high-entropy alloys
Rajeshwar R. Eleti, M. Klimova, Mikhail Tikhonovsky, Nikita Stepanov, Sergey Zherebtsov
Abstract
Abstract Ti-rich body-centered cubic (BCC, β ) high-entropy alloys having compositions Ti 35 Zr 27.5 Hf 27.5 Nb 5 Ta 5 , Ti 38 Zr 25 Hf 25 Ta 10 Sn 2 , and Ti 38 Zr 25 Hf 25 Ta 7 Sn 5 (in at%) were designed using bond order (Bo)-mean d -orbital energy level (Md) approach. Deformation mechanisms of these alloys were studied using tensile deformation. The alloys showed exceptionally high strain-hardening and ductility. For instance, the alloys showed at least twofold increment of tensile strength compared to the yield strength, due to strain-hardening. Post-deformation microstructural observations confirmed the transformation of β to hexagonal close packed (HCP, α ′) martensite. Based on microstructural investigation, stress–strain behaviors were explained using transformation induced plasticity effect. Crystallographic analysis indicated transformation of β to α ′ showed strong variant selection (1 1 0) β //(0 0 0 1) α ′ , and [1 − 1 1] β //[1 1 − 2 0] α ′ .