Effect of martensitic ω phase on mechanical properties of Ti100−xCox alloys with x = 5, 7 and 9

Systematic microstructural investigations in the Ti100−xCox alloys with x = 5, 7 and 9 reveal that the length-scale and distribution of martensitic ω phase can be effectively modified by the additions of small amounts Co. With increasing Co content, homogeneous distribution of nano-scale martensitic ω phase occurs in β-Ti matrix indicating improvement of structural coherency of the ω phase to the β-Ti matrix. A large plasticity of ∼34% combined with the high strength (∼2.9 GPa) of the Ti91Co9 sample can be obtained through the local shear dissipation possibly caused by the structural coherency between ω and β phases.