A Discrete Stochastic Method for Modeling Non-Conservative Plastic Dislocation Processes

Non-conservative processes play a fundamental role in plasticity and are behind important macroscopic phenomena such as creep, dynamic strain aging, loop raft formation, etc. In the most general case, vacancy-induced dislocation climb is the operating unit mechanism. While dislocation/vacancy interactions have been modeled in the literature using a variety of methods, the approaches developed rely on continuum descriptions of both the vacancy population and its fluxes. However, there are numerous situations in physics where point defect populations display heterogeneous concentrations and/or non-smooth kinetics. With this in mind, in this work we present a kinetic Monte Carlo model that discretely captures vacancy generation and transport kinetics acting in conjunction with the evolving elastic fields provided by discrete dislocation dynamics simulations. The two models are coupled via the applied stresses and stress gradients generated by dislocation structures at vacancy locations. To extend the coupled model to the treatment of large systems, we cast the entire elasto-plastic-diffusive problem within a single stochastic framework, taking advantage of a parallel kMC algorithm to evolve the system as a single event-driven process. After introducing the numerical procedure and validation, we compare the method to existing continuum formulations and examine several macroscopic phenomena including non-conservative plastic bypass of a precipitate, dipole coalescence, and vacancy trap formation.