Study on grain refinement of AlB2 structure in aluminium alloys

Aiming at the problem of unclear grain refinement mechanism in aluminium alloys, AlnBn (n = 2-12) clusters and Al-3B alloy were studied by density functional theory methods. The results show that as the cluster size increased, B atoms self-aggregated, and Al atoms surrounded the surface of the clusters. In addition, Al and B atoms formed stable AlB2 triangular structures. The average binding energy gradually increased with increasing clusters size, which indicated that the clusters structures were gradually stable. Range of n = 2-11, the Al(9)B(9 )cluster showed the most stable structure. Electronic properties and interatomic interactions calculation results suggested that there was a minimum electrostatic potential point on the surface of the B atom, and the B atom in AlB2 may be the adsorption site of alpha-Al. The ab initio molecular dynamics simulations results of the Al-3B alloy showed that Al and B generated the AlB2 structure in situ, and Al atoms nucleated and grew on the AlB2 surface. These results can be used to understand the grain refinement mechanism of the Al-B intermediate alloy.