A novel tool to assess the influence of alloy composition on the oxidation behavior and concurrent oxygen-induced phase transformations for binary Ti-xMo alloys at 650 °C

To understand the influence of composition on the oxidation of the Ti-Mo system, a combinatorial approach was adopted whereby a compositionally graded specimen, Ti-xMo (0 ⩽ x ⩽ 12 wt%), was prepared and oxidized at 650 °C. The results show that the scale thickness is independent of the composition and a parabolic law is obeyed in the composition-time domain. An increase in the Mo content degrades the adhesion of the scale by forming a TiO transition layer. Some of the observations including the homogeneous nucleation of β for compositions <∼7.5 wt% Mo and discontinuous precipitation for compositions >∼7.5 wt% Mo in the subsurface region have not been previously reported.