Multiscale analysis of crystalline defect formation in rapid solidification of pure aluminium and aluminium–copper alloys

Abstract

Rapid solidification leads to unique microstructural features, where a less studied topic is the formation of various crystalline defects, including high dislocation densities, as well as gradients and splitting of the crystalline orientation. As these defects critically affect the material’s mechanical properties and performance features, it is important to understand the defect formation mechanisms, and how they depend on the solidification conditions and alloying. To illuminate the formation mechanisms of the rapid solidification induced crystalline defects, we conduct a multiscale modelling analysis consisting of bond-order potential-based molecular dynamics (MD), phase field crystal-based amplitude expansion simulations, and sequentially coupled phase field–crystal plasticity simulations. The resulting dislocation densities are quantified and compared to past experiments. The atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models, and the framework adds mechanistic insights arising from the multiscale analysis. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

OpenPFC: an open-source framework for high performance 3D phase field crystal simulations

“…Moreover, it is notable that the liquid content at the grooves of the solidification front are very short, indicating that the absolute stability limit (planar solidification front conditions) are being approached. This is consistent with past rapid solidification simulations using phase field method [42,43] and amplitude expansion PFC [7,38].…”

“…The most common identified dislocation type is 1 2 ⟨110⟩ (blue segments), which is the major dislocation type in FCC materials [4]. The total dislocation density, approximately 2.5 × 10 16 m −2 , is consistent with the PFC amplitude model simulations and MD simulations for aluminum conducted in [38]. It is also noted that for very rapid solidification rates, the incorporation of two-time PFC dynamics through the use of inertial term (also called 'modified PFC' or MPFC for short [39]) can be used to improve the description of dislocation dynamics within the PFC framework.…”

Coarse-grained modeling of crystals by the amplitude expansion of the phase-field crystal model: an overview

“…figure 8(a)). A recent, remarkable application at this length scale is the simulation of sub-boundaries formation due to orientational gradients in thin aluminum films [76,140] (figure 8(b)).…”

Transport phenomena in complex systems (part 2)

“…Transport phenomena during phase transitions leading to various patterns and microstructure formation are studied in works [33][34][35][36]. These studies are continued in the papers [37][38][39][40], where multiscale modelling of such phenomena based on the phase-field, phase-field crystal, molecular dynamics and cellular automata methods has been carried out. The effects of external processes such as magnetic fields and hydrodynamic flows on transport peculiarities have been analysed in [19,[41][42][43].…”