When multiphase materials are subjected to a plastic deformation at finite temperature, the dislocation-mediated plastic flow and heterogeneous phase transformation (PTs) could simultaneously occur. However, it remains as a challenge using single-scale techniques to fully address the coupled dynamics between dislocations and PTs due to the emergence of a wide range of length scales. A multiscale computational tool that can not only resolve the micrometer-level dislocation pileup but also the subsequent atomic-level structural changes, such as the phase nucleation and growth, ahead of the pileup tip is not well established up to date. To meet this need, in this work, we expand our previous concurrent atomistic-continuum (CAC) methods through: (i) unifying the atomistic and continuum descriptions of dislocations and PTs in one single framework; (ii) enabling a smooth passage of not only dislocations but also PTs from the atomistic to the continuum domain; and (iii) furnishing it with a phonon density states-guided finite temperature algorithm. Thereafter, the applicability of the newly developed CAC is demonstrated through a series of simulating the PTs induced by a dislocation pileup at the phase boundary (PB) in a prototype multiphase materials under deformation at finite temperature. Two major findings are: (a) the critical stress needed for the phase nucleation significantly reduces with the increase of the temperature and the number of the dislocations piling up at the PB; and (b) the micrometer-level long-range stress field induced by the dislocation pileup dictates the phase growth rate and in turn, the subsequent microstructure evolution. This knowledge may be used to support the development of a strategy for discovering and arresting hidden phases through a ‚Äúdefect-controlled‚Äù process in multiphase materials under a well-controlled deformation.        

Concurrent Atomistic-Continuum Simulations of the Defect-promoted Phase Transformation in Multiphase Materials under Plastic Deformation at Finite Temperature

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