Effect of Thermo-mechanical Treatment on Microstructure and Mechanical Properties of Two-phase TiNbO Alloy

We designed the composition of alloy with Ti-8Nb-0.5O (at. %) and fabricated in high vacuum arc-melting furnace. This work was focused on the effect of thermomechanical treatment on microstructure and mechanical properties. Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), X-ray Diffraction analysis (XRD), Micro Vickers Hardness Tests and Tensile Tests were utilized to characterize the alloys. The annealing temperature has a significant effect on the microstructure and mechanical properties of TiNbO alloy. When the alloy was annealed at 300℃, 400℃ or at hot-rolled state, there were just α and β phases in the alloy. When the alloy was annealed at 500℃, 600℃, the alloy recrystallized and harmful ω phase appeared, which increased the modulus and strength of the alloy greatly. When the alloy is annealed at 700℃, the alloy recrystallized completely without ω phase. When we accelerated the cooling rate after annealed, the martensitic transformation appeared, which restrained the appearance of ω phase and reduced the modulus.