Synthesis and Microstructural and Optical Characterization of Fe-Cu Metastable Alloys for Enhanced Solar Thermal Absorption

This paper investigates the synthesis, microstructural characterization and optical testing of Fe-Cu metastable alloy system for selective solar absorption applications. The system was produced by mechanical alloying (MA) using high energy ball milling, while monitoring its crystallographic morphology via X-ray diffraction (XRD) from the initial as-is mixture up to the one produced after 8 h milling time. The resulting homogeneous, quasicrystalline microstructure was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to verify the sought result of efficient inter-diffusion of Cu and Fe. Optical spectroscopy results exhibit enhanced absorption in the Vis-NIR wavelength range with increased milling time, while the trends of absorptivity curves had clear correlations with the microstructural evolution depicted in XRD results. High energy ball milling is proven to be an economical and effective method for producing homogeneous phases of originally immiscible materials, Cu-Fe in the current case, with enhanced selective-absorption characteristics.