Ultrahigh strength and large plasticity of nanostructured Ti62Nb12.2Fe13.6Co6.4Al5.8 alloy obtained by selectively controlled micrometer-sized phases
School of Engineering
We report that the strength and plasticity of Ti62Nb12.2Fe13.6Co6.4Al5.8 alloy can be modulated by selectively controlled micron-sized phases, i.e. β-Ti phase and twined (CoFe)Ti2 phase. It is found that the alloy with micron-sized β-Ti phase embedded in nanostructured matrix possesses lower yield strength but higher ultimate strength relative to the alloy with micron-sized (CoFe)Ti2 phases. The plastic strain and ultimate strength of the alloy with micron-sized β-Ti phases is as large as 22.1% and 2826 MPa, respectively. The work-hardening exponent n of the alloy with micron-sized β-Ti phase, 0.12, is far greater than 0.008 for the alloy with (CoFe)Ti2 phase. Such significant and different mechanical properties are attributed to the roles and response of micron sized phases during deformation process.