Superplasticity of near-γ TiAl alloys

Superplastic deformation in near-gamma TiAl alloys have been investigated in the temperature range 950 degrees C similar to 1 075 degrees C, and at strain rates of 2x10(-4)s(-1)similar to 8x10(-5)s(-1). The alloys exhibit an excellent superplasticity, the maximum elongation reaching 570%. The strain rate sensitivity reaches 0.5 and above at higher than 1 000 degrees C and lower than strain rate of 1.7x10(-4)s(-1). The apparent activation energy of the alloy is up to 302 kJ/mol. The superplastic mechanism is grain boundary sliding accommodated by slip in the grains.