Author: Rashid Ali a, Muhammad Umair Akhtar a,b, Aqib Zahoor a, Fahad Ali a,c,*, Sergio Scudino c, Rub Nawaz Shahid a,c, Naeem ul Haq Tariq a, Vikas C. Srivastava d,e, Volker Uhlenwinkel e , BA Hasan a , Jurgen Eckert c,f
Institute: a Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, Islamabad (PIEAS), Islamabad, 45650, Pakistan b National University of Sciences and Technology, Islamabad, Pakistan c Leibniz IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069, Dresden, Germany d National Metallurgical Laboratory, Jamshedpur, 831007, India e Leibniz Institut für Werkstofftechnik, Universitat € Bremen, Badgasteiner Straße 3, 28359, Bremen, Germany f Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstraße 12, A-8700, Leoben, Austria
The study of thermal and structural characteristics of mechanically ground nanostructured Al-Cu-Fe quasicrystals is a topical task in materials science. These quasicrystals, possessing unique properties such as high strength, low thermal conductivity and anomalous corrosion resistance, open up new prospects in various fields, including aircraft construction and microelectronics.
Single-phase nanostructured quasicrystalline Al-Cu-Fe powders with different grain sizes were synthesized by mechanical milling of precipitated low-density icosahedral quasicrystals. The structural evolution at different temperatures was studied using high-energy synchrotron X-ray diffraction. The thermal expansion coefficient was determined based on the changes in the interplanar spacing. The diffraction results showed changes in the lattice parameters, grain size, and quasi-lattice strain with increasing temperature. Upon heating, noticeable grain coarsening in various nanostructured quasicrystalline powders occurred at a certain critical temperature, which was clearly related to the duration of the milling process. In powders milled for 1 and 80 h, grain coarsening occurred at 923 and 573 K, respectively. For all samples, the activation energy of grain coarsening (EGG) was approximately 30–35 kJ/mol. The formation of the β-phase of Al(Cu,Fe) with the B2-structure was also observed upon heating of powders ground for 10 hours, and the temperature of the onset of formation of this phase was inversely proportional to the grinding time.
During mechanical grinding, not only particles are ground, but also their crystal structure and thermodynamic characteristics change. Melting point, heat capacity and thermal stability are key parameters that can be significantly changed as a result of this process. Experimental results show that along with the formation of new phases, changes in the particle size distribution are observed, which in turn affects the mechanical properties of the sample.
A detailed analysis of the obtained data will allow us to better understand the mechanism of formation of nanostructures and their influence on the physicochemical properties of Al-Cu-Fe quasicrystals, as well as to develop new models for predicting their behavior under various operating conditions.