<p>In this study the grain refining
efficacy of AlTiB, AlB and AlNbB master alloys on a Ti-free AlSi alloy is
investigated. In particular, the performance of commercial Al5Ti1B and Al5B
master alloys is compared to that of a lab-made Al2Nb2B and two Al2NbxB (x=1
and 2 wt.%) made in an industrial pilot scale facility. Although chemical
inoculation does not change the morphology of the grains, which is always
equiaxed dendritic, it is found that the grain size progressively decreases
with the master alloy addition rate and the achievable final grain size is
strongly dependent on the chemistry of the master alloy used. The experimental
results demonstrate that AlNbB > AlB > AlTiB in terms of grain refining
efficacy. The dataset consists of original grain size data measured from polarised optical images of cast samples.</p>