Atomic-scale nucleation pathways of MgAl2O4 particle in molten steel

DFT calculation was used to obtain the structures and thermodynamic properties of (MgAl2O4)(n) clusters. Atomic-scale nucleation pathway of MgAl2O4 has been discussed by two-step nucleation mechanism. (MgAl2O4)(n) could formed by five pathways, and the possible pathway from highest to lowest is: the reaction of [Mg], [Al] and [O] > the reaction of [Mg], [O] and (Al2O3)(n) > the reaction of [Mg] and (Al2O3)(n) > the reaction of [Mg], [O] and bulk-Al2O3 > the reaction of [Mg] and bulk-Al2O3. (MgAl2O4)(n) could formed more likely by the reaction of [Mg], [Al] and [O] at the high values of log([%Mg][%Al](2)[%O](4)), more likely by the reaction of [Mg] and (Al2O3)(n) at the high values of log([%Mg](3)/[%Al](2)), more likely by the reaction of [Mg], [O] and (Al2O3)(n) (or bulk-Al2O3) at the high values of log([%Mg][%O]). Thermodynamic driving force for the formation, aggregation and transformation of (MgAl2O4)(n) increased with the decreasing of temperature.