The introduction of composite materials with a quasi-crystalline matrix (QCM) opens up new prospects in the development of materials with unique properties. Quasicrystals with icosahedral symmetry are characterized by the absence of translational periodicity, which determines their high hardness, low thermal conductivity and resistance to corrosion. Reinforcement of QCM with other metals allows for additional modification of their properties, adapting them to specific applications.
This work is devoted to the study of the structure, electrical and thermal properties of a composite obtained by mechanical grinding (MG) of a mixture of Al-Cu-Fe and Sn powders with subsequent annealing. Mechanical grinding promotes the formation of nanostructures and ensures uniform distribution of the reinforcing phase of tin in the Al-Cu-Fe CCM. Annealing at high temperature promotes the formation of a quasi-crystalline phase and improves interfacial adhesion between the matrix and the reinforcing component.
X-ray diffraction and scanning electron microscopy (SEM) revealed that after MI and annealing, a composite consisting of a quasicrystalline Al-Cu-Fe matrix and uniformly distributed tin inclusions is formed. Electrical conductivity measurements showed that the addition of tin leads to an increase in the conductivity of the composite compared to pure Al-Cu-Fe CCM. The thermal conductivity of the resulting composite was also studied and found to be slightly higher than that of pure CCM, which is probably due to the high thermal conductivity of tin. The results demonstrate the possibility of purposeful modification of the CCM properties by reinforcing with tin, opening up prospects for the creation of new functional materials.
In this paper, we investigate the structure and electrical and thermal properties of Al-Cu-Fe quasicrystal (IQC) reinforced by the addition of soft Sn phase (10 to 30% by volume). The material was obtained by mechanical milling followed by heat treatment. After 40 h of milling, the IQC-Sn nanocomposite powder contains the IQC phase and crystalline phases such as B2-Al(Cu, Fe) (a = 0.29 nm; cP2) and monoclinic Al13Fe4 (a = 1.549 nm, b = 0.808 nm, c = 1.248 nm; α = γ = 90°, β = 107.72°; mC102). It was found that the IQC phase contains ordering, which manifests itself in the form of a superlattice (311111), reflecting the IQC structure.
Annealing of the milled IQC-Sn powder at 800 °C results in an increase in the proportion of the IQC phase compared to the crystalline phases. The nano-quasi-crystalline and nano-crystalline nature of the IQC and crystalline phases in the milled and annealed powders was confirmed by transmission electron microscopy. Nanobeam diffraction (NBD) of the annealed samples confirmed the presence of nearly five-fold symmetry characteristic of the IQC phase. Electrical and thermal properties of both the milled and annealed samples were analyzed.
The transport properties (electrical and thermal) of the annealed sample were higher than those of the ground IQC-Sn nanocomposite powders. The highest ratio of electrical conductivity to thermal conductivity (σ/κ∼4704 SC/W) was recorded for the annealed IQC-20Sn sample. The obtained results suggest that the annealed IQC-Sn nanocomposites are promising for use as thermoelectric materials.
Author: Yagnesh Shadangi, Shradha Bhatt, Priyatosh Pradhan, Archana Tiwari, Ajay Tripathi, Kausik Chattopadhyay, Nilay Krishna Mukhopadhyay
Institute:
Department of Metallurgical Engineering, Indian Institute of Technology (BHU) Varanasi, Varanasi 221005, Uttar Pradesh, India
Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
Four BK21 Seoul National University, Educational Research Unit for Global Creative Leaders, Seoul National University, Seoul 08826, Republic of Korea
Department of Physics, Institute of Sciences, Banaras University, Varanasi 221005, Uttar Pradesh, India
Department of Physics, School of Physical Sciences, Sikkim University, 6th Mile Samdur, Gangtok 737102, Sikkim, India