Substructure in a creep deformed lamellar TiAl alloy

Abstract

It has recently been demonstrated that the primary creep of a fully-lamellar (FL) TiAl alloy can be significantly reduced by a prestraining technique. Specifically, when a FL-TiAl specimen was first crept to a few percent of strain at high stresses (>240 MPa), the specimen became more resistant to a subsequent creep deformation at lower stresses (<240 MPa) even after a prolonged loading. Although changing interaction between strain hardening and recovery processes which strongly affect the creep rate at a given temperature and stress. Both strain hardening and recovery processes are intimately related to the mobilization and immobilization of dislocations. In the present study, the substructure of crept alloys is examined in order to understand how and to what extent a prestraining can affect the creep behavior of the FL-TiAl alloys. The influence of lamellar orientation (with respect to the stress axis) in the deformation substructure is also investigated.