Abstract:

Creep behavior and mechanisms of Ti-47Al-2W-0.5Si cast alloy have been investigated. The results show that the creep rupture time at 650℃ decreases rapidly with the increasing of applied stress, and can be expressed by the formula lg^t_f=10 lg^R+30. The creep rupture time and minimum creep rate fit a linear double-logarithmic relationship, and can be described with the revision of Monkman-Grant relationship. Its creep strength is comparable to the density-corrected strength of nickel-based corrosion-resistant superalloy K438G. Step-like various load creep has similar deformation characteristics compared with constant-load creep. Long period aging at 800℃ coarsens the lamellar structure, and subsequently lowers the creep rupture life. Dislocation gliding and deformation twinning are attributed to the dominant creep mechanisms.

Key words: intermetallics, high-temperature structural materials, TiAl, mechanical properties, creep