A study based on jogged-screw dislocations for high temperature creep in Ti alloys

The objective of this paper is to revisit the present status of the high temperature creep of alloys with particular reference to models based on the motion of jogged-screw dislocations. Models based on this concept have been previously attempted to describe the creep in pure metals and alloys (Barrett and Nix, Acta Metall., 13 (1965) 1247). Now, in light of emerging new experimental evidence. a modified version of this model appear to be appropriate for the case of creep in both disordered alpha-Ti alloys and ordered Ti-Al based intermetallic alloys based alloy. TEM investigations have shown that in both cases dislocations of screw character dominate the deformation microstructures in these alloys and that jogs much taller than atomic dimensions form along the dislocations. The predictions of the modified jogged-screw model are compared with creep data for Ti-6242 and gamma-TiAl alloys. (C) 2001 Elsevier Science B.V. All rights reserved.