Abstract
The liquid–liquid phase separation (LLPS) behavior of Fe50Cu50 melt from 3500 K to 300 K with different rapid quenching is investigated by molecular dynamics (MD) simulation based on the embedded atom method (EAM). The liquid undergoes metastable phase separation by spinodal decomposition in the undercooled regime and subsequently solidifies into three different Fe-rich microstructures: the interconnected-type structure is kept in the glass and crystal at a higher cooling rate, while the Fe-rich droplets are found to crystalize at a lower cooling rate. During the crystallization process, only Fe-rich clusters can act as the solid nuclei. The twinning planes can be observed in the crystal and only the homogeneous atomic stacking shows mirror symmetry along the twinning boundary. Our present work provides atomic-scale understanding of LLPS melt during the cooling process.
Highlights
The typical microstructure of phase separation is classified into an interconnected structure or a droplet-like structure by mechanisms such as spinodal decomposition and nucleation growth [1,2,3]
Because the liquid–liquid phase separation (LLPS) competes with crystallization, relatively, in metallic alloy, it is difficult to obtain the interconnected structures by spinodal decomposition [4,5,6]
At the cooling rate of 6.4 × 1012 K/s, the interconnected-type structure is kept in the glass; at the cooling rate of 6.4 × 1011 K/s, the interconnected-type structure is more pronounced and kept in the crystal, some small Fe-rich droplets occur in both liquid and solid; at the cooling rate of 1.28 × 1011 K/s, the droplet-type structure is formed in the crystal
Summary
The typical microstructure of phase separation is classified into an interconnected structure or a droplet-like structure by mechanisms such as spinodal decomposition and nucleation growth [1,2,3]. Because the LLPS competes with crystallization, relatively, in metallic alloy, it is difficult to obtain the interconnected structures by spinodal decomposition [4,5,6]. Most of the microstructures obtained by the phase separating alloy are the droplet structure, which is formed by nucleation and the growth reaction. The bulk glass with a nano-sized separated phase shows high strength and toughness [7,8,9,10,11] due to the enhancing overall plastic deformability through the formation of a multiple-branched shear band [7,10,11]. The vitrification and crystallization of phase-separated metallic liquid at atomic level is still unknown
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