Shrinkage and Segregation Kinetics in an MC Simulation

N ow we come back to the synergy of curvature-driven effects and inverse Kirkendall effect at the shrinkage stage. The above-described MC-model was used to simulate the collapse of the nanosheU with = 7a, = 17a (the total number of atoms 

The formation of hollow nanosheUs and their collapse are presented as two stages of one process with crossover between regimes being determined by the competition 

dr Ks t.la, K = 10, e ) segregation of B species near the internal surface leads to slowing down of the nanoshell shrinkage. 

2) Conventionally, the critical void size is determined only by vacancy supersaturation and temperature. In our case, the concept of a critical size should be reconsidered. Void behavior, besides local vacancy concentration, is also determined by the gradients of vacancies and the main component, so that a thermodynamically stable void might be kinetically unstable. The approximate criterion of central void growth is given by Equation 7.145. 

3) In the process of internal void growth, the initial reserves of the chemical driving force (concentration and chemical potential gradients) ran out, so that at some moment (at some void radius) the chemical driving force becomes less than the capillary forces (and the corresponding vacancy drop between internal and external boundaries). Thus, one has a crossover from formation to shrinkage. 

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