GRAIN REFINEMENT OF ALUMINIUM USING NIOBIUM ADDITIONS.

An investigation was made into the behavior of niobium as a grain-refining agent in aluminum. It was found that highly effective refinement could be obtained at moderate overall Nb levels of around 0. 1 wt-% and above. These satisfactory results were obtained, however, when inoculation was carried out using additions of a master alloy (Al-5Nb), which contained about 5 vol. -% of Al//3Nb intermetallic particles embedded in the matrix. Other forms of addition were found to be less effective.