Grain Refining Efficiency and the Role of Alloying Elements in Determining the Nucleation Potency of LaB6in Aluminum Alloys

This work discloses the refinement mechanism of LaB(6)in three binary aluminum alloys via grain refinement experiments, model calculation, and cooling curve analysis. The refining efficacy of LaB(6)in aluminum was influenced by an interfacial relationship which can be controlled by alloying with different solute elements. Al atoms attach directly onto the surface of the LaB(6)substrate during solidification. Because the lattice parameter of alpha-Al increased after alloying with larger metal atoms, the lattice mismatch between LaB(6)and Al matrix decreased. This investigation reveals that the nucleating behavior of LaB(6)can be influenced by adding solute Si, Mg, and Cu, and thereby offers a pathway for controlling the content of aluminum alloys.