The mechanism of climb in dislocation–nanovoid interaction

Techniques of atomistic simulation have been employed to determine the mechanism of the newly observed process of climb of a dislocation line during depinning at a nanosized void. The analyses prove that, in contrast to the conventional notion of dislocation climb, this unique process is not a diffusion controlled phenomenon. Instead, the gradient of structural energy of the system alone suffices to produce the climb motion. The energetics of this process has been investigated through molecular statics and dynamics computations and the causes of discrepancies are discussed. In order to further explore these concepts in a quantitative manner we have developed a robust simulation strategy to accurately measure the reduction in energy of the nanovoid during dislocation climb. The results explain the lowering of the critical depinning load and the effect of thermal facilitation on void-induced climb. Moreover, we highlight the key role played by the curvature of the dislocation line in mediating this mechanism.

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