Use of constitutive description in an interpretation of creep in Ti-52Al intermetallic

The present work investigates compressive creep curves of a Ti-52Al intermetallic which were obtained at the temperature 1100 K and applied stresses in the interval from 50–300 MPa. They illustrate a pronounced change of creep behaviour at about the applied stress 200–225 MPa. A description of the curves by means of constitutive equations suggests an activity of two processes in the course of creep. The initial process, which is rapidly exhausted, is connected with a strong increase of the internal stress. The other process realizes the major part of the creep strain. It is connected with an increase of the internal stress (high-stress curves) or with its decrease (low-stress curves). Some microstructural arguments supporting the different behaviour are given.