Investigation of partitionless growth of ε -Al 60 Sm 11 phase in Al-10 at% Sm liquid

Recent experiments on devitrification of Al90Sm10 amorphous alloys revealed an unusual polymorphic transformation to a complex cubic crystal structure called the ε-Al60Sm11 phase. Molecular dynamics simulations of the growth of the stoichiometric ε-phase seed in contact with an undercooled Al-10 at% Sm liquid are performed to elucidate the microscopic process of transformation. The as-grown crystal and undercooled liquid possess similar local order around Al atoms whereas a rigid network defined by the Sm sub-lattice develops during the growth. Using a template-cluster alignment method, we define an order parameter to characterize the structural evolution in the system. Estimates of the attachment rate is ${R}_{{\rm{a}}}=8.70\times {10}^{-4}$ Å-2 ns-1 and detachment rate is ${R}_{{\rm{d}}}=3.83\times {10}^{-4}$ Å-2 ns-1 at the interface between ε-Al60Sm11 and Al-10 at% Sm liquid at 800 K.