Assessment and modelling of isothermal forging of intermetallic compounds - Part 1 - TiAl

In this, the first of four papers concerned with the isothermal forging of intermetallic compounds, Ti-48Al-2Mn-2Nb (at.-%), an alloy based on the gam ma-TiAl intermetallic phase, has been deformed men over the temperature and strain rate ranges 1050-1125 degrees C and 3.0 x 10(-4)-30 x 10(-2) s(-1) respectively. Examination of the stress-strain curves shows an increase in flow softening behaviour with increasing temperature ann decreasing strain rate, contrary to what might have been expected. Forged microstructures ind icate that grain refinement via dynamic recrystallisation has occurred resu lting in a fine, almost fully gamma microstructure. Constitutive, data calc ulated from initial stress-strain curves (for example activation energy of deformation and strain rate sensitivity have been used to model deformation behaviour with a reasonable degree of success.