The enhanced work hardening rates of the constituent TiAl and Ti3Al phases in a lamellar microstructure

The minimum creep rate of a two-phase TiAl/Ti3 Al alloy with a lamellar microstructure is significantly lower than the minimum creep rates of single-phase TiAl and Ti3Al alloys tested in compression at the same temperature and applied stress. It has been proposed previously that the arrangement and increased density of geometrically necessary dislocations in a plastically inhomogeneous lamellar microstructure enhance the work hardening rate and decrease the minimum creep rate compared with the constituent single-phase alloys. In support of this proposition, a strong correlation has been found between the increase in dislocation densities and decrease in minimum creep rates of the TiAl and Ti3Al phases within the lamellar microstructure compared with the constituent single-phase alloys.