Growth mechanism and kinetics on re-entrant corner and twin lamellae in an fcc crystal

Abstract

Based on the twin lamellae mechanism of crystal growth proposed by Ming and Sunagawa, the growth mechanism and kinetics of an fcc 111 crystal surface on which emerged a re-entrant corner and two types (A-type and B-type) of twin lamellae have been theoretically analyzed. Through analytical calculations we have demonstrated that the energy barrier for 2D-heterogeneous nucleation at the B-type twinned area is smaller than that for 2D-heterogeneous nucleation at a sub-step induced by a stacking fault and a re-entrant corner induced by A-type twinning and smaller than that for conventional 2D-homogeneous nucleation making use of the first neighbour approximation. Although the nucleation barrier for 2D-heterogeneous nucleation at the re-entrant corner and also the A-type twinned area is not larger than that at the sub-step created by a stacking fault, its nucleation rate is smaller since the growth mechanism of the crystalline cluster should be considered. Our suggestion on the shape of 2D-heterogeneous nucleation is demonstrated by a Monte Carlo simulation. Thus, the twin lamellae growth mechanism is more active than the stacking fault mechanism which has been considered in our previous work.