Abstract
In solid-liquid systems, macroscopic solids lose their equilibrium and melt in a manner that results in overall movement of the solid-liquid interface. This phenomenon occurs when they are subjected to temperature gradients or external stress, for example. However, many experiments suggest that the melting of nano- and micro-sized metallic nuclei follows a different process not described by traditional melting theory. In this paper, we demonstrate through simulation that the melting of solid nuclei of these sizes occurs via random breaches at the interfaces. Moreover, this breaching process occurs at the exact solid-liquid equilibrium temperature and in the absence of any external disturbance, which suggests the name “self-instability” for this melting process. We attribute this spontaneous instability to the curvature of the samples; based on the relationship between the sample’s instability and its curvature, we propose a destabilizing model for small systems. This model fits well with experimental results and leads to new insights into the instability behavior of small-sized systems; these insights have broad implications for research topics ranging from dendrite self-fragmentation to nanoparticle instability.
Highlights
In solid-liquid systems, macroscopic solids lose their equilibrium and melt in a manner that results in overall movement of the solid-liquid interface
In a finite SL system, the kinetic equation of the interface is written as dr dt where instead of the interfacial profile being described as a function of h, it is described as a function of r, which is the radius of the sample
Under the combined influence of the curvature and fluctuations, breaches can initiate on the SL interface at the equilibrium temperature and lead to the instability of the nuclei, which is discussed in a later section
Summary
In solid-liquid systems, macroscopic solids lose their equilibrium and melt in a manner that results in overall movement of the solid-liquid interface This phenomenon occurs when they are subjected to temperature gradients or external stress, for example. We demonstrate through simulation that the melting of solid nuclei of these sizes occurs via random breaches at the interfaces This breaching process occurs at the exact solid-liquid equilibrium temperature and in the absence of any external disturbance, which suggests the name “self-instability” for this melting process. We attribute this spontaneous instability to the curvature of the samples; based on the relationship between the sample’s instability and its curvature, we propose a destabilizing model for small systems. The influence of fluctuation was studied using both MD and the finite difference method (FDM); the stochastic nature of the self-instability www.nature.com/scientificreports/
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