Effect of potent TiB2 addition levels and impurities on the grain refinement of Al

In the present work, the effect of potent TiB2 particle addition levels and impurities on the grain refinement of two Al compositions was investigated. Results showed that no effective grain refinement was achieved in high purity Al (HP-Al) up to particle density levels as high as 2.5 x 10(14)/m(3). In commercial purity Al (CP-Al) fine grain refined structures were observed with merely a particle density of 0.35 x 10(13)/m(3). As more particles were added into the CP-Al melt, the number of grains formed showed an overall increase while the calculated particle efficiency showed a general decrease, consistent with the prediction of interdependence theory. Such results show that the impurities in CP-Al play a significant role in refining the grain structures. (C) 2016 Elsevier B.V. All rights reserved.