Concentric nano rings observed on Al-Cu-Fe microspheres

Abstract

It is well known that when particle size is reduced, surface effect becomes important. As a result, micro/nanoparticles tend to have well defined geometric shapes to reduce total surface energy, as opposed to the irregular shapes observed in most bulk materials. The surface of such micro/nanostructures are smooth. Any deviation from a smooth surface implies an increased surface energy which is not energetically favorable. Here, we report an observation of spherical particles in an alloy of Al65Cu20Fe15 nominal composition prepared by arc melting. Such spherical particles stand out from those reported so far due to the decoration of concentric nanorings on the surface. Three models for the formation of these concentric ring patterns are suggested. The most prominent ones assume that the rings are frozen features of liquid motion which could open the door to investigate the kinetics of liquid motion on the micro/nanometer scale.

Ordering of Nanoparticles along Concentric Nanoings Observed in Al-Cu-Fe Alloy

“…1(a), which has been reported previously [2][3]. The new finding of the present work is shown in Figs.…”

“…The feature of rings in Fig. 1(c) is in consistent with the typical concentric nanorings reported so far [3].…”

“…It has been revealed that, the asprepared alloys of this composition by arc melting consist of β-phase with composition of AlFe(Cu) and cubic crystal structure [2]. Further, it has been reported that the β-phase is of spherical morphology and the surface of the spheres are decorated with concentric rings [2][3]. The diameters of the most inner ring was found to be in the order of 1 µm, while that of the outer-most ring is in the order of 5 µm.…”

Specimen plane orientation determination for analysis based on scanning electron microscope: Comparing top‐down and side‐view approaches

“…The alloy was prepared by arc melting pure aluminum, copper, and iron with a nominal atomic composition of Al 60 Cu 25 Fe 15 , the details of which are described in reference (Li et al, 2016). The prepared alloy appears to be porous and brittle.…”

“…The specimen used for testing is Al‐Cu‐Fe alloy (Li et al, 2016) and the particles of spherical shape found in it are of interest for this study. While the particles have complicated structures and phases, it is justified to consider them as single crystals of cubic structure since only the surface is of interest in this study.…”