Boron introduction into Al-Cu-Fe alloys is a promising method for modifying their structure and properties. High-energy ball milling (HEBM) is an effective method for synthesizing nanostructured materials, including quasicrystals, bypassing thermodynamic limitations. This work is devoted to the study of the influence of HEBM on the structure, microhardness, specific electrical resistance and absorption of solar energy of the Al59Cu25.5Fe12.5B3 alloy.
Mechanical alloying was carried out in an argon atmosphere using a planetary ball mill. The phase composition and microstructure of the powders were studied using X-ray diffraction and transmission electron microscopy. Microhardness was determined using the Vickers method, specific electrical resistance – by the four-probe method, and solar energy absorption – using a spectrophotometer.
The results showed that after a short period of VESHI, a nanostructured structure consisting of a mixture of quasi-crystalline and crystalline phases is formed. An increase in the grinding time leads to a further decrease in the grain size and an increase in the defectiveness of the structure. The introduction of boron helps stabilize the quasi-crystalline phase and increases the rate of its formation. The microhardness of the samples subjected to VESHI increases significantly compared to the initial alloy. The specific electrical resistance also increases with increasing grinding time, which is associated with a decrease in the mean free path of electrons due to scattering at grain boundaries and defects. The absorption of solar energy in the visible region of the spectrum increases after VESHI, which can be used to create solar absorbers.
Nanoquasicrystalline Al59Cu25.5Fe12.5B3 alloy and associated crystalline phases were prepared by mechanical alloying using a high-energy ball mill and subsequent compaction by cold isostatic pressing. In this paper, the focus is on the synthesis processes, changes in structure and microstructure, thermal stability, microhardness, and electrical and optical characteristics of the nanocrystalline Al59Cu25.5Fe12.5B3 alloy, which is considered as a selective absorber of solar energy.
Structural transformations of mechanically alloyed and heat-treated AlCuFeB powders were analyzed using X-ray diffraction. In particular, the influence of milling duration and heat treatment on the formation of quasicrystals and related crystalline phases was investigated in the AlCuFeB system. Microstructural features, morphology, and elemental microanalysis of the original and milled powders were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The elemental composition of the milled AlCuFeB powders was determined by inductively coupled plasma atomic emission spectrometry. The thermal stability of the AlCuFeB powders was studied using differential thermal analysis, and the change in particle mass during annealing was studied using thermogravimetric analysis.
Stable quasicrystalline phase Al59Cu25.5Fe12.5B3 and crystalline solid solution Al(Cu,Fe) were obtained by intensive milling for 1 hour. The term “ultrafast synthesis” describes the formation of quasicrystalline i-phase solely by high-energy ball milling under short-term impact, without subsequent heat treatment. However, even after annealing, single-phase quasi-crystal was not achieved. The size of the quasi-crystalline phase was calculated by the Williamson-Hall method and optimized by the Rietveld refinement procedure, and ranged from 53 to 61 nm. The particle size distribution of the milled AlCuFeB powders was determined by laser diffraction in the range from 0.1 to 50 μm. The microhardness of the samples strengthened after grinding and heat treatment was estimated using a Vickers indenter, and their specific electrical resistance was estimated using a four-probe measurement method at room temperature. Spectral absorption analysis of consolidated grinded samples was performed in the ultraviolet, visible and near infrared regions. It was found that the presence of a quasi-crystalline phase in the AlCuFeB alloy significantly increases the microhardness, specific electrical resistance and, in particular, the absorption of sunlight.
Author: Meysam Amini, Mohammad Reza Rahimipour, Seyed Ali Tayebifard, Yahya Palizdar
Institute: Department of Ceramics, Materials and Energy Research Center, Karaj, Iran, Semiconductor Department, Materials and Energy Research Center, Karaj, Iran, Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, Karaj, Iran