Liquid phase separation in undercooled Cu–Co alloys under the influence of static magnetic fields

Abstract

Undercooling of Cu-based alloys often induces metastable liquid phase separation followed by rapid solidification of separated liquids. The rapid solidification can help freeze in the morphology of a higher-melting liquid and eases difficulties in studies of liquid phase separation kinetics. In the present work, the influence of static magnetic fields on liquid phase separation in bulk Cu 84 Co 16 composition was investigated. Inductively melted samples were glass-fluxed, undercooled and solidified under uniform and non-uniform magnetic fields generated by a superconducting magnet. Solidification microstructure of the phase-separated samples was examined using an optical microscope. The imposition of the magnetic fields, both uniform and non-uniform, altered the morphology, segregation pattern and size distribution of Co-rich droplets due to liquid phase separation. The imposition of the non-uniform magnetic fields with positive and negative gradients brought about segregation of the Co-rich droplets at the top and the bottom side of the samples, respectively. Such influence of the static magnetic fields is interpreted by assuming intensification of convective flow and Kelvin force-controlled migration of the Co-rich droplets. This article is part of the theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

Heterogeneous materials: metastable and non-ergodic internal structures

“…In this paper, a new theory of the unsteady-state thermo-solutal growth of spherical particles in a metastable surrounding is developed so that the main nonstationary corrections produced by fluctuations in the fundamental contribution of the particle's growth rate are found. This paper, which is directly connected with experiments and simulations presented in papers [11,12], opens a new perspective on the theory of phase transformations at the intermediate stage, which is presented in the next paper by Eugenya Makoveeva & Dmitri Alexandrov [15]. In this paper, a new theory describing the evolution of a phase transformation process in supersaturated and supercooled liquids is considered with allowance for the fluctuation corrections in particle's growth rates [14].…”

“…Here, we consider phase transition processes and phenomena occurring in non-equilibrium systems such as deeply undercooled liquids and supersaturated solutions under the influence of different additional factors representing driving forces and leading to unusual dynamical behaviour. A theoretical study of liquid phase separation in undercooled alloys under the conditions of static magnetic fields is presented by Dandan Zhao & Jianrong Gao [11]. Here it was found that the imposition of static magnetic fields can alter the morphology, segregation and size distribution of droplets due to liquid phase separation.…”

Solidification of Immiscible Alloys under High Magnetic Field: A Review

“…Zhao et al [92] explored the effects of a non-uniform magnetic field generated via a superconducting magnet on the solidification behavior of Cu 84 Co 16 immiscible alloys. The application of inhomogeneous magnetic fields with positive and negative gradients led to Co-rich droplets to segregate at the top and bottom of the sample (see Figure 10), respectively, which indicates that the reversal of a sign of the gradients gives rise to the opposite separation patterns.…”

“…All cross-sections were chosen to be parallel to the direction of the magnetic fields. The minor phase with dark contrast is the Co-rich solid solution, and the matrix phase with bright contrast is the Cu-rich solid solution [92].…”

Pulsed electric fields induce modulation of protein liquid–liquid phase separation

“…Conversely, for homopolymers and nanocomposites the mechanisms of LLPS formation have already been well investigated. [29][30][31][32][33][34][35][36] In this context, external force fields, especially electric fields (EFs), controlling motion and phase separation of nanoparticles were applied to obtain and prepare nanomaterials with specific structures and functions, e.g. carbon nanotubes, nanowires and conducting polymers.…”