Local deformation of Ti6Al4V modified 1 wt% B and 0.1 wt% C

Ti–6Al–4V–1B–0.1C is a modification of the mostly used titanium alloy Ti–6Al–4V (Ti64). TiB whiskers (around 5 vol%) precipitate in the Ti64 matrix in two size classes during the solidification of the powders mixture and before consolidation. The hot deformation of this material is studied between 850 and 1100 °C and at strain rates 0.001–10 s−1 using compression tests. The processing maps using the modified dynamic mechanical model are applied to correlate the flow behaviour with the dissipated energy. At low strain rates the large values of efficiency of energy dissipation are related to superplasticity, which is also observed in the microstructure of a sample deformed at 950 °C up to 1 of true strain. The low values of dissipation efficiency at high strain rates and the flow instabilities are related to cracking and debonding of the fraction of larger TiB at low temperatures, and to porosity evolving at the triple grain boundaries at temperatures above 1000 °C. A method to correlate the microstructure with the local deformation parameters is developed using finite elements methods. The parameters of the constitutive equations can be correlated with the processing maps and the microstructures verifying the different deformation mechanisms in the studied range.