The effects of trace rare earth cerium on as-cast structure of industrial pure aluminium were investiagted.The refinement and modification mechanism of cerium on microstructure were analyzed.The results show that trace cerium can increase the perturbation of supercooling and solute instability

and release a large amount of latent heat

which lead to the decrease of interface stability and the refinement of microstructure and grain size.Cerium has a higher chemical activity

so it is easy to generate newαphase core and promote grain refinement.The rare earth compounds formed on the interface will fill the defects on the interface surface to promote the transformation of the impurity phase into pellets

and adsorb the impurity atoms to enrich at the grain boundary.