In 1984, the discovery of quasicrystals (QC) in Al–Mn alloy by Shechtman and coworkers created a new class of aperiodic crystals, revolutionizing traditional crystallography. Quasicrystals, part of a family of complex intermetallic compounds, exhibit aperiodicity, high strength, excellent wear resistance, low friction coefficient, as well as low electrical and thermal conductivity, and good corrosion resistance. Since the initial discovery of quasicrystals in Al–Mn alloy, many such phases and alloys have been found in aluminum-based systems. Among the common aluminum-based ternary quasicrystalline alloys, the Al–Cu–Fe system has been actively studied due to its non-toxicity, cost-effectiveness, and availability of constituent elements. Due to their aperiodic structure and excellent functional properties, they are promising structural materials for coatings, reinforcement of aluminum-based composites and as substrates for catalytic activity. The composition in the range of 58–70 Al, 20–28 Cu and 10–14 Fe (in atomic percent) ensures the formation of a stable IQC phase in ternary Al–Cu–Fe systems.
Mechanically induced structural transformation in the Al–Cu–Fe nanocomposite with a quasicrystalline matrix reinforced with tin is a complex process initiated by external mechanical action. Unlike traditional materials, where deformation leads to dislocations and grain boundary sliding, in this nanocomposite the quasicrystalline matrix exhibits different response mechanisms.
The introduction of tin into the composite structure plays a key role in modulating its mechanical properties. Tin, having a lower melting point and plasticity compared to Al–Cu–Fe, forms individual nanosized inclusions uniformly distributed in the quasi-crystalline matrix. These inclusions serve as stress concentrators when a load is applied, initiating local structural rearrangements.
The process of structural transformation begins with elastic deformation of the matrix, followed by plastic flow of tin inclusions. Further increase in load leads to the formation of nanocracks and shear bands near tin inclusions, which subsequently propagate into the quasi-crystalline matrix. These processes facilitate energy dissipation and increase the overall strength of the composite.
Author:Yagnesh Shadangi, Vikas Shivam, Somarouthu Varalakshmi, Joysurya Basu, Kausik Chattopadhyay, Bhaskar Majumdar, NK Mukhopadhyay
Institute: Department of Metallurgical Engineering, Indian Institute of Technology (BHU), Varanasi, 221005, Uttar Pradesh, India, Department of Materials Engineering, Institute of Advanced Defence Technology, Pune, 411025, Maharashtra, India