Microstructural characteristics of isothermal forging in cast Ti–6Al–4V/TiC composites

Abstract

The microstructural response of cast Ti–6Al–4V based composites, containing 10 and 25 vol.-%TiC reinforcement, to isothermal forging was investigated in the temperature range 800–950°C and the strain rate range 2 × 10⁻⁴–8 × 10⁻² s^−l. The extent of the fracture of TiC dendrites was found to be strongly dependent on strain rate in Ti–6Al–4V/10 vol.-%TiC, and dendrite fracture occurred only at strain rates higher than 10⁻² s^−l. In Ti–6Al–4V/25 vol.-%TiC, dendrite fracture occurred in the entire strain rate range. Recrystallised α phase with an equiaxed morphology was found to be favoured by low strain rate, whereas, increased strain rate retains the platelike α phase inherited from the as cast condition. It was found that the TiC reinforcement enhances α phase recrystallisation via particle stimulated nucleation.

MST/1915