Ni-Mo-Cr-Ti alloys are one of the proposed structural materials for molten salt breeder reactors. In the current work, the evolution of precipitates in the alloy at various stages of thermo-mechanical processing followed by thermal ageing at 750 degrees C is studied. The microstructure after thermal ageing for various durations shows the presence of 'MC'-type carbides with different morphologies and compositions. Formation of carbide networks with bulky titanium-rich 'MC' carbides of irregular morphology and spherical 'MC' around it is observed in the early stages, while fine uniform dispersion of 'MC'-type needle-like carbides that possess a cube-on-cube orientation relationship with the FCC matrix is observed in the latter stages. High-resolution transmission electron micrograph reveals the presence of misfit dislocations on the semi-coherent interface between the fine needle-like MC carbides and the matrix which is attributed to the lattice parameter mismatch between them.
展开▼
