High temperature creep behavior of in-situ TiC particulate reinforced Fe–Cr–Ni matrix composite

The high temperature creep properties of the composites containing 5, 10, 16 vol% TiC particulate were investigated in the temperature range 973–1223 K and the stress range 40–160 MPa. The composites exhibit pronounced decrease of the creep strain rate and increase of the apparent activation energy and the threshold stress with increasing the volume fraction of TiC particulate. The creep life of the composites containing 5 and 10 vol% TiC particulate is longer than that of matrix alloy. By considering the threshold stress, all creep strain rates of the composites can be rationalized by a power-law with a stress exponent of 5. Transmission electron microscopy examination of the deformation microstructure reveals the local climb mechanism of dislocations acts as the predominant deformation mode in the composites. The dislocations are generally pinned by TiC particles and are bent to a high curvature on climbing over the particles. Thus a significant amount of new dislocation lines has to be created, leading to an increase of the threshold stress.