Abstract
Despite the continuous and remarkable development of experimental techniques for the investigation of microstructures and the growth of nuclei during the solidification of metals, there are still unknown territories around this topic. The solidification in nanoscale can be effectively investigated by means of molecular dynamics (MD) simulations which can provide a deep insight into the mechanisms of the formation of nuclei and the induced crystal structures. In this study, MD simulations were performed to investigate the solidification of pure Aluminium and the effects of the cooling rate on the final properties of the solidified material. A large number of Aluminium atoms were used in order to investigate the grain growth over time and the formation of stacking faults during solidification. The number of face-centred cubic (FCC), hexagonal close-packed (HCP) and body-centred cubic (BCC) was recorded during the evolution of the process to illustrate the nanoscale mechanisms initiating solidification. The current investigation also focuses on the exothermic nature of the solidification process which has been effectively captured by means of MD simulations using 3 dimensional representations of the kinetic energy across the simulation domain.
Highlights
The dependence of the mechanical properties of crystalline materials on their grain structure has been known since the early 1950s, when Hall and Petch proposed a relationship connecting the yield strength to the grain size [1,2]
The simulation domain is a 25 × 25 × 25 nm3 rectangular box containing 1,000,188 Aluminium atoms initially arranged in a face-centred cubic (FCC) lattice
Since the average simulation domain temperature is a linear function of time, dynamic quantities such as the potential energy and the mean square displacement (MSD) is plotted as a function of temperature
Summary
The dependence of the mechanical properties of crystalline materials on their grain structure has been known since the early 1950s, when Hall and Petch proposed a relationship connecting the yield strength to the grain size [1,2]. The manufacturing process selected (casting, heat treatment, welding) as well as the corresponding process parameters (e.g., cooling rate) play an important role in the final properties of the manufactured material. This is because the micro- and nano-structure of metals is dependent on the phase transformation phenomena occurring during solidification and nucleation. The real time observation and interpretation of the phenomena occurring during solidification in the bulk material still remains a challenging task [4]
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