Electron back-scatter diffraction study of inoculation of Al

The microstructure of cast commercial-purity aluminium inoculated by additi on of an AI-TI-C grain refiner has been studied by scanning electron micros copy and electron back-scatter diffraction (EBSD). It is found that a small fraction of the TiC particles present in the melt act as nucleation centre s for grains. EBSD shows that the aluminium grains have a crystallographic cube-cube orientation relationship with the particles on which they nucleat e. Nucleation occurs only on the largest particles, consistent with model p redictions. Despite potential thermodynamic instability, TiC particles are effective nucleating agents.