Abstract
Recent investigations have demonstrated that the interface spacing in fully lamellar microstructures has a major influence on the creep behavior of γ-TiAl-based alloys. In this paper, the dependence of the creep properties on interface spacing in fully lamellar Ti-46.5 at.% Al-4 at.% (Cr, Nb,Ta, B) sheet material was studied. Creep tests were conducted over a temperature range of 700 to 800 °C and at stresses between 100 and 260 MPa. The results indicate that the primary creep strain as well as the minimum creep rate decrease with decreasing interface spacing. A model which considers the limitation of the free dislocation path by stored dislocations as well as by geometrical obstacles was applied to explain the role of the interface spacing on both the primary creep strain and secondary creep rate. The applicability of the model has been verified by comparing calculated creep curves with experimentally obtained ones.
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