Effect of boron on the structure and mechanical properties of Ti-6Al and Ti-6Al-4V

Boron alloying was found to have a beneficial effect on the plasticity of Ti-6Al and Ti-6Al-4V (wt.%) as-cast alloys for contents within the solubility limits (up to around 0.05 wt.%) and to enhance their strength and hardness HV in the range of the existence of metal-boride eutectic (up to 2.0 and 2.5 wt.% B studied, respectively). The boride reinforcement contributes much to the hardness and strength of the Ti-6Al and Ti-6Al-4V alloys, increasing them by 1.5-2 times at room temperature to 400 °C. Monovariant eutectics (Ti88.8Al11.2) + TiB and (Ti84.9Al11.4V3.7) + (Ti96.9V3.1)B were found to solidify at compositions Ti-6Al-1.8B and Ti-6Al-4V-2B (wt.%) and at temperatures of 1530 and 1515 °C, respectively.